Diagnosis and Repair of Your Imperial's Cylinder Heads, Gasket & Valve Covers


Imperial Homepage -> Repair ->Engine -> Cylinder Heads


There were some differing opinions on the best way to seal what's variously called valve, rocker, or cam covers.  I won't use cut rubber valve cover gaskets since it's just too difficult to get a good seal.  I like valve cover gaskets made of cork , but if it has to be rubber, then they should have a steel shim reinforcement.  Just remember not to overtighten valve cover gaskets and split them if they're cork.  I glue them down with weather- stripping adhesive and remember that the cover has to be straight and true.

Question from Bob:

What's the difference between "open chamber" and "closed chamber"?

Reply from Mark:

I guess I'll start with a general description of a combustion chamber found in a typical American V-8 wedge engine. The combustion chamber is comprised of the top of the piston and the recessed areas of the head located directly over the cylinder. There are four of these areas on each head of a V-8 engine. Within these areas, sitting side by side, are the two "mushroom head" valves. These valves cover two holes, one being the intake port, the other the exhaust. And, of course, off to one side, there's a threaded hole where the spark plug comes in. So far, so good, no? OK, now, the difference between an open chamber head versus a closed chamber one is in the size of these recessed areas. On an open chamber head, the recessed area is large, about the full size of the piston diameter (or "bore"). On a closed chamber head, the recessed area is as small as possible, no more than just around the two valves and the spark plug hole, a somewhat triangular area. The rest of the combustion chamber, which would have been recessed on an open chamber head, is filled in and at the same level as the flat, mating surface of the head.

Question from Dana:

After taking the valve covers, rockers and push rods out I have made the following unsettling discovery: Three pushrods look like drawn bows - can't wait to get the head off and see what the valves look like. I expect the same for the other cylinder bank when I get to it. So, the questions are: 

1) Suggestions for how this might have happened and for how it can be avoided in the future. 

2) Where can I get replacements? 

3) Should I just give up while I'm ahead (?) and part the car out? Or at what point does this make sense?


From Kne:

1. Bent push rods are almost always the result of over-revving the engine, but a broken timing chain, or timing chain that jumps a tooth can also do it. 

2. Junk yards, auto parts stores? Are you out of the U.S.? 

3. No. Some new push rods and valves and you should be fine. Pistons are usually not hurt, but you will see the "kiss marks" on them. I have had a couple such engines that were fine after I replaced the push rods and valves. (and not all valves needed replacement) One engine was out of a car (318) that some of the local teen-agers had "tried" to blow up by putting it in first and then driving it up and down the street with the pedal to the metal. It was brutal. Then they parted the car out and gave me the engine. (thinking it was toast) All the pistons had deep kiss marks, all the push rods were bent, only one exhaust valve was bent. Replaced bent valve and pushrods, put it in a daily driver, and it worked fine, no lower end damage.

From Paul:

Some years ago, after allowing my '64 to sit for a couple of years, (protected indoors), I started it and drove it 20 or 30 miles to thoroughly warm it up and circulate all fluids. When I started it the next morning, I heard some bad sounds and it had a noticeable miss and valve train noise like collapsed lifters will sound. Upon taking the valve covers off, I found a couple of bent pushrods just like you describe. A good friend and retired mechanic from a local Chrysler dealership said that what probably happened was that the old gasoline "varnished" the valve stems, then a couple of valves stuck open after the engine cooled. When the engine turned over the next morning, the pushrods dropped out of place and then were bent when the lifter rose up on the next turn of the camshaft. He was emphatic that I NEVER risk running a car on old gas again. I never have either!!!!! Replacing the pushrods was all I needed to do except get rid of the old gas. This mechanic also suggested using an upper cylinder lube in the gas for a couple of tanks....I think it was called "Marvel Mystery Oil" or something like that.

Question (318):

 Will the cylinder heads from a 318 will work in a 360 and what is the difference between these two engines?


From Kne:

I'm not sure what heads were used on '81's, but the bigger valve heads are actually 360 heads which were used on 4bbl 318's for certain years, and not a 318 head with bigger valves. Possibly/sounds like they used them on the EFI if that's the specs on your valves, but that's what they are, 360 heads. If they have the little valves they be 318 heads.  I wonder why the 360 wasn't the standard engine on the later Imperials? That would be a nice swap, as a 360 will bolt right in where a 318 was. 360 has a different balance, but that's no problem. Seems like the 360 would have been more "Imperialistic" than the 318. ??

From Dick:

Actually, the performance with the 318 is really quite good, even with the weight of the '81 coupe, as long as it is an EFI car. I have no complaints with the 318. Is the 360 an overbore, or a longer stroke? I know more about Packards, but I note that my 374 Packard is noticeably noisier mechanically than my 352, and they are both fresh tight engines, I ascribe it to thinner cylinder walls. Much more poop, but less luxury like, the 352 is whisper quiet.

From Dan:

I agree, since a 440 was obviously out of the question, the least they could have done was to put their top dog engine in their top of the line car. However, considering the problems some people are having just keeping theirs running, I think an EFI 360 would be a little optimistic at this point, right?

Follow-up from Kne:

360 is both bored and stroked. 360 bore is 4.00", stroke is 3.58". (318 is 3.91" bore and 3.31" stroke) The 360 is cast with a different core casting, so the cylinder wall thickness would be the same. Yes the 318 is a fine engine, but I still will say that a 360 would be more "appropriate" for an Imperial, and would make for a safer car when passing or entering the freeway. Even if one's driving style does not take advantage of the greater torque and power most of the time, what power you do use is produced with much less effort. More "Imperialistically". 318 performance is "quite good", but 360 performance is "most excellent". :-) Think of it like this: the 318 is good mustard, but the 360 is Grey Poupon.

From Tony:

My 318 EFI runs a lot better than I had expected. I have put 3000 miles on it in just over 3 weeks and it has "not missed a lick". 2000 on a cross country drive done in 3 days. The car had been in the garage for years and had not been driven. It got 17.6 mpg on the trip. It does seem to be a little slow out of the gate but it picks right up. My wife's 86 Fifth Ave., 318, with a non lockup 904 could run past it real easy. I drove the Imperial through Texas, New Mexico and Arizona at 85 Mph tank after tank after tank. I've had a lot of 318 engines and I would give this one a solid B. I know it's early yet to be betting the farm on this 318 but I think its a good one. I agree the 360 should have been in there but Chrysler had a lot of trouble going on in 81 and maybe somebody thought the Imperial didn't need a 2 or 3 mpg DROP in its EPA rating!! Who knows!

Question from Justin (413):

I have a question about the engine in my '64 crown. I have replaced the plugs, wires, cap, and rotor, and have put a edelbrock 750cfm carb on (the carb is a temp. wile the carter is being rebuilt). and still the # 7 & 8 cilinders are dead. They are both getting spark and the firing order is right.


From Paul:

Have you done a compression test?

Also, what test are you doing to determine that numbers 7 & 8 are dead? How do you know that they are getting spark? Have you taken the plugs out and seen that they have been firing? If they still look brand spanking new, they haven't fired. If they are firing, then there could be a valve problem, piston problem, cracked casting, or broken head gasket. These would show up as very low or no compression on those cylinders.

If there is a cracked head or cylinder block, you may see bubbles and/or oil in the radiator, or even a loss in coolant while the engine is running. There could also be coolant in the crank case. A blown head gasket could also cause these things.

Broken pistons and burned valves have other unmistakable symptoms all their own.

From Bob:

Try doing a compression check on the whole engine! That will tell a lot!!!

Question from Fredrick (413):

My mechanic replaced the plugs and set the points/distributor (which is pretty new) but I'm still skipping a cylinder in there somewhere. He gave it a good check, and I trust this guy (I've used him for years) but he admits he doesn't know these big 413's as well as he knows other engines. He suspects it may have something to do with the carburetor and vacuum ports. Any ideas?


From  Pete:

You may want to temporarily disconnect the brake booster vacuum line, plug the manifold fitting, and see if the miss is still there. I've worked on a couple of Mopar small blocks where you'd *swear* that a plug, wire, or head gasket was bad -- the miss was that pronounced. Well the first time I 'bit" and pulled the LH cylinder heat thinking that a recent valve job had been poorly done. No trouble found. It turned out to be a bad brake booster causing a big vacuum leak in the cylinder fed by the vacuum fitting equipped runner. Talk about feeling stupid.... The second time I experienced the condition I was ready and waiting for it. The owner of the car was prepared for the worst and thought I was a miracle worker when I found the source of the problem in 30 seconds. I didn't tell about the first time ;-)

From Mark:

Remember the old vacuum-leak test. Take the air cleaner off and start the car. let warm up to curb idle. now put your palm over the throat of the the carburetor as you get closer to it, a rise in the idle indicates a vacuum leak. the worse the leak the better it runs with your hand over it. I agree though, the power Brake booster is notorious for leaks. So is the the vacuum advance on the distributor. Misses are easy to find by unplugging each wire in succession and holding it with an insulated pair of pliers back on the plug. You should hear the the miss come and go. My biggest whine on mine was the the old AFB carburetor was so leaky around the shafts that the the idle fluctuated too much. I rebuilt it but couldn't find anyone to shim the shafts for me. I finally broke down and bought a new Carter AFB. The one caveat there was that the new one has the same throat size as my '68 rather than the smaller diameter that was on my '63.

Tip and Question from Jack (413):

What a neat idea, change the valve stem seals with the heads still on the motor. Three hours, much lost skin, one launched valve spring. That's just the right head. Had to use the rope thru the plug hole trick to keep the valves from dropping into the block. Just how big are the chambers on a 65 413 head anyway? Had to feed about five feet of rope into the cylinder to get the valves to stay up. Yes, I turned the crank by hand till it stopped and sometimes the valve still moved enough to prevent the keepers from coming out. One side done, one side to go. BTW, the old seals were completely shot.


From Kerry:

Much easier way is to get the tool that screws in the spark plug hole. Apply air pressure and it holds the valves up. Only costs a few bucks but does require an air compressor. Sunday afternoon, I changed 12 seals on a Ford V6 in about 3 hours and that included time to build a spring compressor lever. Mine were shot also.

From Bill:

Those are closed chamber heads but if the piston is at BDC the cylinder will hold a lot of rope. I like the air fitting method better myself but as has been pointed out before, one little mistake such as the hose popping loose, you're out of air and whichever valve you have loose may go down the hidey-hole to be retrieved only with head removal, so the rope method is probably ultimately safer. Another tip, before doing anything else, use a 1/2" drive socket of appropriate size to fit on the spring retainer, along with an extension to keep your hand away from the hammer (Three Stooges anyone?), hold it on each retainer and tap sharply with a hammer, this will loosen the hold of the retainer on the locks and really helps with older motors where the parts have really bedded in together. Then when you apply the tool to push down the retainer it should easily come free of the locks. Loosening the keepers like this also helps when disassembling the head on a bench with a "C"-type valve spring tool.

Follow-up from  Jack:

First, I don't have an air compressor. Second, the spring compressor is the kind that has legs that hooks the coils and screws down on the retainer. One sharp rap with a hammer and any stuck keepers popped loose. Third, rotated the crank until the piston was barely below TDC and it still took a lot of rope to hold the valves up.

Question from Zan (413):

My car had been smoking' slightly before a the valve gasket replacement, and now that I've replaced them, it smokes even more. I find that it is dripping oil, on the passenger side nearest to the windshield, right on the exhaust manifold and the exhaust pipe.  Any ideas?


From Pete:

I see that you've already received advice regarding a warped/distorted rocker cover. I hope that turns out to be the problem because its an easy fix. Here's another possibility, though: I've had a few cars (GM products with the 455 V8, 3.0 & 3.8 V6) that had very high oil consumption. This was surprising because other GMs didn't have that problem and the engines in question had fairly low mileage. Pulling the rocker cover on the 455 caused some real excitement because about 1 1/2 quarts of oil dumped onto the exhaust manifold. Turns out that poor earlier maintenance caused the oil drain holes at the back of the heads to clog up. So, the oil level in the rocker are steadily rose until the valve seals were submerged and overwhelmed. Cleaning the drain-back holes completely solved my problems and I could go 3000-4000 miles without adding oil. Mopar B & RB engines don't have oil drain-back holes in the heads, but they do have channels (one located between the intake and exhaust valves at each cylinder. With all the crud that you loosened up you may have clogged those areas (or they may have been clogged for a long time). I'd pull a cover and use a slim screwdriver to probe the channels between each set of valves. If there's gunk there get it out. Also check a little further down where the inboard head bolts are located.

From Jay:

Recent experience has taught me not to bother looking for clogged oil drain-back galleries in a '62 413 head - there aren't any. I went crazy one Saturday with the same problem that Zan is having. The only difference is that instead of a leaky valve cover gasket, I had a crankcase vent/draft tube that would DUMP about 6 oz of oil out of this tube after a run at highways speeds, usually when I had pulled the Imperial into a steep driveway (lifting the front of the car up and thus tilting the engine back.) Figuring that a drain-back blockage in the head that was causing a back up of oil into the valve cover (VC) at freeway RPMs, I removed the VC and started probing around for a clogged hole somewhere using an ice pick. I took the advice/experience of one of my Ford friends, even took to calling our troubleshooter extraordinaire Dick Benjamin at home for advice. There were no holes small enough to be clogged. What I came to realize it that our 413 heads don't have drain-back holes, but rather have HUGE caverns for the oil to drain back into the lifter area. When I would shine the flashlight down between the rockers and pushrods, I could just barely see the ends of the lifters. Lifters are internal, and the fact that I could see them leads me to conclude that this is where the oil MUST flow to get back down into the bottom end of the engine. My oil dumping problem was caused by a combination of backpressure (excessive blow-by) in the crankcase and restrictions in the crankcase ventilation. My particular engine doesn't have a positive crankcase ventilation (PCV) setup (yet), but has the typical vented oil cap on the drivers side VC and a "draft tube" vent on the passenger side VC. This disgustingly messy tube connects to the VC and passes down the side of the engine, venting near the left torsion bar. If enough oil backs up into the VC and the engine is tilted back - out dumps the oil. Zan. You may have a similar backpressure problem causing an unusual amount of oil to collect in the VC. A slight leak around the VC gasket would most likely leak more oil with oil collecting there rather than just draining back like it should. Without enough venting, oil leaks in general will be worse, being that the oil is being forced out of the engine under pressure. If you have one of these "draft tubes", I recommend removing it and getting a pipe cleaner and lacquer thinner and clean all the gunk out of it. Do the same for your oil filler cap as well. You engine will breath better and I'll bet any remaining oil leak will like a little less. BTW- Around that time I was doing all of this, I wanted to somehow test the amount of blow-by that the engine was producing. Figuring that the only vent the crankcase had to the outside word was through the valve covers, I removed the draft tube and oil filler cap and installed - get this - rubber gloves! Using a couple of rubber bands, I capped the vents with the rubber gloves. When I installed the second glove, both of them inflated! As I rev'ed the engine, the gloves would swell up. I figured that a little swelling was alright, but if the gloves exploded or blew off the VCs that I might have a problem with excessive blow-by. The gloves stayed on and I couldn't get them to explode or fly off. It was interesting and funny to see a 413 with "hands".

From John:

This sounds to me as though the gasket isn't properly seated. If the car has a/c this is a tough spot to deal with if the outer section of the heater box isn't removed first. The fact that you can see oil dripping from there confirms this. I think you'll need to replace the gasket again & if you didn't do so get yourself an inch pounds torque wrench at Sears. The FSM calls for 40 inch lbs which is really not very tight at all & needs to be uniform at all 4 bolts. This is nearly impossible without a torque wrench unless you've done this a few hundred times. Uneven tightness will distort the cover & cause it to leak.

Question from Jay (413):

Is there a rule of thumb for a engine that blows smoke only when it's sat, not running for more than a day? Our '66 doesn't blow smoke during acceleration or deceleration, but will blow blue clouds for about two minutes when it's been sitting for a day or more. Someone once told me that this is caused by motor oil in the top-end of the engine that seeps down into the combustion chamber thru worn valve guides when the car sits for long periods of time. When you fire up the engine, it takes a couple of minutes of idling to burn all the oil away. It makes sense to me. What's your opinion?  Do you think that this could be fixed without pulling the heads?


From Dick:

One thing you can try which has a fair chance of helping, and it's cheap and easy: Remove the valve covers and ream the crud out of the drain holes at each end of each head so that any oil which accumulates in the rocker chamber drains back to the crankcase as quickly as it did when the car was new. You will need a new set of valve cover gaskets and a very long (18" or so) handled brush with about a 5/16" diameter to reach all the way to the oil pan from the top of the head. Try a gun shop for this. You cannot damage anything, and you might be amazed at how gunked up the drains are. This will be an opportunity to stick a blunt but small probe through the valve springs to test the resilience of the valve stem seals. These are small mushroom shaped cups that fit over the valve stems against the head boss and keep the oil in the rocker chamber from coating the valve stems so that it cannot be sucked into the intake chamber. If these are hard as glass, you can replace them without removing the head, but it's a little tricky. You have to compress each valve spring, remove the keepers and the top washer, then relax the spring compressor and take off the spring and the old stem seal. Then replace everything the same way and go on to the next valve. The tricky part is keeping the valve up tight against the head while you do this. I use a modified spark plug which I connect to my air compressor (of course the other valve on this cylinder has to be closed, so you have to be prepared to rotate the engine a couple of times to do all the cylinders.) You will need a set of 8 exhaust and 8 intake valve stem seals from your local parts store, but they are cheap. Your major expense will be to buy a good valve spring compressor, but you will use it many times on your cars. You can rent one also. Your other major expense will be hand cleaner.

From Bob:

I heard another trick for keeping the valves up that sounds good although I have not tried it myself. Instead of compressed air that can kick back at you or surprise you at the wrong time, take the spark plug out, bring the piston up near TDC but leave 30 to 45 degrees of rotation in your pocket for the last part of this maneuver... Take a length of soft cotton clothes line, feed it into the spark plug hole and fill the combustion chamber with it, turn the crank to push the piston with the clothes line on top of it up tight against the bottom of the valves and this will hold the valves up in position while you take the keepers and springs off. Less of a chance of dropping a valve or getting your turning bar thrown back at you.

From Paul:

The seals on the valve stems are fairly easy to replace and very inexpensive. You only have to remove the valve covers and rocker shafts, (put compressed air through the spark plug opening into the cylinder to keep the valves up while you remove the valve springs to get to the seal.) I replaced them on a '68 Dodge Monaco with the 440 and the oil consumption went from 1 quart every 200 miles to better than 1,500 miles. I would sure try replacing the valve stem seals first before making the final decision to overhaul. Main indicator was heavy blue smoke on startup with very little smoke at any other time.

Question from Joe (413):

Can 440 cylinder heads be used on a 413 engine?


From Mikey:

Its not the rocker arms that are the problem, its the pushrods. The 413 probably had the separate rocker shaft pedestals, the 440 had the cast in ones. Go to any parts store with counterman that have actual intelligence ( versus virtual intelligence , as in " my computer doesnt go back that far ) and you will find 2 different pushrods listed for the 440 and I believe the 413. In essence, for this particular situation, the heads don't know they are on a 413 block, but the rocker arms are wondering where the pushrods they used to mate with are at.

From Michael:

I wouldn't even bother with your local parts store unless its been around for 40 years and one or more of the Owners or employees is driving an old 413 MAX WEDGE Belvedere......instead I would call your local MOPAR dealer, ask for the parts department, and hopefully the guy behind the desk KNOWS what an Imperial is, if NOT then ask for HIS boss, at any rate get the phone number of the MOPAR Tech Line which they had up until 6 years ago the last time I called them.

From Bill:

The answer is yes. I installed 452 smog heads on a standard bore 413 a few years ago with no problems at all. 413 maximum performance (max wedge) heads had removable-pedestal rocker assemblies, and '63 and earlier big block heads have only 4 valve cover bolt holes. Max wedge heads had valves so big that 413 blocks were notched at the factory for use in max wedge cars, but this isn't necessary with 452 heads and I doubt if it would be for other 440 heads.

Question from David (413):

I know there's interchangeability between 440 and 413 blocks and cylinder heads, but I can't find specifically which, if any, 440 heads I can use on a 1960 413 block. Can somebody point me to the right reference? This is not my project, I'm asking on behalf of the builder. And yes, it's for an Imperial.


From Mikey:

Any B or RB head will physically interchange. Before anyone jumps to conclusions, the Stage series or racing heads and the B-1 and a few of the aftermarket heads use different manifolding or different geometry, so lets just stay within the realm of stock mass produced 361-383-400-413-440 passenger cars and avoid the race only and exotic stuff.

That said, now you get into the 3 major differences in all these heads:
1. Number of valve cover bolt holes - 4 or 6 holes.
2. Valve diameters - early engines had smaller intake and exhaust valves.
3. Open and closed combustion chambers. - Does the head have a completely open combustion area or is it partly filled in or closed in, depending on how one describes it

To be general,unless they have previously been swapped, the '60 would have had the closed chamber and smaller valve diameters and 4 valve cover bolts. I swapped an entire 440 in place of the 413 in my '62. So take the following with a grain of salt in deciding what cylinder heads to look for.

1. The valve cover bolt holes are not an issue except for being able to access them to replace a valve cover gasket. Its a complete pita to get at the corner bolt holes on the heads, but not impossible. Dont let the valve cover bolt holes be an overwhelming concern in this area, the clearance between the valve covers themselves and the heater box, brake booster and all that are the same , and there is always a way to get a universal swivel socket or extension or modified wrench etc etc at the valve cover bolts. Many mopars used studs on the valve covers, so then all you have to do is fight with nuts and washers.

2. The valve sizes, who cares.....its not like its going to hurt the engine to install a head with larger valves than one that had the smaller valves. In a purely theorhetical state the larger valves breathe easier and work better, hence the reason automakers went with them. In an Imperial with the kind of rpms that are usually seen and if youre not doing anything with the rest of the engine such as adding a hotter cam or going to some high compression pistons, headers etc etc.....its probably going to be a moot point.

3. The open or closed chambers, a 60 probably had an advertised 10.1 or something very close compression anyway and ran on gasoline of a higher octane than we can get now anyway. It would have had the closed chamber head from the factory. If you swapped to an open chamber, the volume in the combustion chamber increases a bit, and may drop the compression say, half a point or so , down to perhaps 9.5 to 1. There is nothing wrong with that, considering the octane ratings of the fuel you see now anyway. There are some slight differences in how an open chamber and a closed chamber head act when the combustion takes place, but again in the real world seat of the pants driving, I doubt youd ever notice it in a heavy, tall geared car like an Imperial .

I'm not endorsing or knocking any particular kind of cyl head here, but if you found a set from a '68 383 or a '72 440 or a '65 413 and they were in good shape mechanically - no burnt or cracked valves, good valve stem seals, everything meets specs as far as mechanical condition - any set would work fine.

For reference, find a copy of the Mopar Performance B-RB engine book at any Chrysler dealer or look for maybe a copy of HP Books How to Build Big Block Mopar, or go to Allpar or the Mopar Web Ring on the web...any of these can give you excellent reference information if you want more in depth technical info.

From Charles:

I did this swap and put in a very mild cam (one step from stock) and the to items lowered the compression to the point that a have less off the line than I started with. So the old heads are rebuilt and going back on the car. If I am wrong about this, someone please correct me as I would like to run the bigger valves.

Follow-up from Demetrios:

Your loss off the line is most likely due to the larger cam. Larger cam means more duration and overlap, which typically favors high rpm torque at the expense of lower rpm. If I am correct, you must have gained upper end, but you may not fully notice that unless you have a decent exhaust system and your 4 barrel carburetor opens completely at wide open throttle.

But I think Mikey is correct that the compression ratio may have also dropped some with the later heads. I think that the late 60's 440's had domes on the piston to compensate for the higher volume in the heads in order to retain their 10.1:1 compression ratio. So, there is a chance that the reduced compression ratio plays a part in your lost low end, but the biggest part is probebly the bigger cam.

Personally, I would be willing to sacrifice a bit of low end for a stronger upper end (both my Imperials are set that way), but in order to really be able to take advantage of the upper end potential, you need the better exhaust and fully opening carburetor (and may be an extra hole in your air cleaner, that will reduce air cleaner restriction at high rpm's). Also, the bigger and/or lower compression ratio cam may alow you to advanve the timing some more. That may give you back much of the lost low end. But a free exhaust will allow you to advance even more before your engine starts knocking (I assume you are using premioum here, that's what these engines need).

Question from Ron (440):

Are the valve covers for a 440 interchangeable with valve covers on a 413?


From Larry:

Valve covers for the big block engines will interchange, IF the number of bolt holes are the same on the cylinder head as on the valve cover (four versus six). The older 350/361/(383/413/426 engines used four mounting bolts, the later engines use six, 383/400/440. (better clamping and less leaking) Differences will also be noticed in the location and type of plug wire mounting brackets, type and location of oil fill opening, PCV valve location and style of PCV valve, heater hose clamp bracket. Some of the later covers have a different shape also.

From Greg:

I think they are the same. In fact 383 valve cover will fit but they don't have the brackets for the plug wires.

From John:

Depends on the vintage of the 413. The bolt-pattern changed somewhere in the 413 production run, maybe as early as late '59. I remember double checking the valve covers on my '59 Crown to make sure I was buying the right gaskets. A good way to verify is to thumb thru the valve cover gasket catalogs at your local auto parts store. Fel-Pro and Detroit gasket have both the early 413 gaskets and the later 413/440 style.

From Mike:

It depends on the year. If I recall correctly, the 62 and earlier 413's used a 4 bolt hole cover. In 63. Chrysler changed the design to the 6 hole style with 4 holes running along the lower side to provide better sealing. Even then, the B and RB motors are tough to seal properly for any long period of time. The gasket surfaces MUST be perfectly straight and that is hard to find after well intentioned owners go on a tightening binge. I finally gave up on my tow vehicle (77 Ramcharger with a 400 w/a torque cam) and bought the new chrome jobs. Not original but they work.

Question from Glenn (440 with cylinder head problems):

While I am driving my '67 Imperial, I notice an extensive amount of blue smoke wafting from under the hood of the car. I am attributing this to "blow-by". What can be done to correct this problem. When I purchased this fine example last October, the previous owner informed me that he did aa compression test on the car and came out with the following results: 

Left Bank going from front to back: 

Cylinder 1 - 115 -145 PSI

Cylinder 2 - 45 - 60 PSI

Cylinder 3 - 120 - 160PSI

Cylinder 4 - 180 PSI

Right Bank going from front to back: 

Cylinder 5 - 165 PSI 

Cylinder 6 - 170 PSI 

Cylinder 7 - 165 PSI 

Cylinder 8 - 160 PSI

The FSM states that the Compression pressure with the engine warm, spark plugs removed, and a wide open throttle should be between 130 - 165 PSI with a maximum variation between cylinders of 25 PSI. I have been using Rislone in the motor since I purchased the car in the hopes to increase compression. I have been told by a number of people to use "Marvel Mystery Oil" to a) help to increase the compression. and b) to help clean the valves. I am told that the low compression is being caused by the Valves not closing properly. Any thoughts?


From Dick:

The stuff in the bottles will help your car only by lightening the load it has to carry (by removing money from your wallet). Your cylinders are numbered 1,3,5,7 front to back on the driver's side, and 2,4,6,8 front to back on the passenger's side. Your # 3 cylinder almost certainly has a burned exhaust valve. 

If you listen to the tail pipe at idle, you will hear a chuff-chuff-chuff sound, right? (If this is not true, you have another, probably more expensive problem). When you crank the starter, you hear an unevenness to the cranking RPM before it starts, too, right? The only cure for this is a valve job, sorry. You can do most of the labor yourself, if you have a good set of tools and don't mind getting dirty and sore. You would be best off to pull the heads (I'd do both sides) and take them to a shop. If you do this part of the labor, you'll be out about $500 by the time you are back on the road, maybe less, and you'll have a perfect running car that will amaze you with its power and smoothness . The blue smoke from under the hood is indeed blow-by, and if your PCV system is fully functional (shake the PCV valve to make sure it rattles, and verify the suction hose is hooked up and producing vacuum at the valve cover end), then you have so much blow-by that your engine needs a total rebuild, now we are talking real money here. Again, if you do the R&R and disassembly - reassemble, you can save a lot of money, but you are still going to be out $1200 or so before you are back on the road. You'll also know a lot more about engines than you do now, unless you have done this a few times before.

From Phil:

I used to do a lot of cylinder heads, but have never seen a Mopar head from the factory with a "hardened" guide. I've seen the later models with an induction hardened exhaust seat, but never a guide. It wouldn't have been cost effective to do it that way. Don't know what you're talking about a "typical" guide problem" either with big block Mopars. If they're sucking oil, the valve seals are bad. Any car is like this, all the big block Mopars I've seen with bad guides had way in excess of 100,000 miles. Any 383-400-440 I have ever had that had bad oil consumption either had bad rings or a real bad oil leak. I have a 77Dodge truck with 145,000 miles and a 63 300 with a 115,000 miles and neither one has an oil consumption problem. If you do run them hard, they will use a little more oil, but if you're using a quart of oil every 300 miles something is wrong, that is not typical oil usage for a big block Mopar. I find one quart every 2000 miles is more typical on a used motor and have had several that didn't use any. I have seen several GM motors, especially Chevy's, with their O Ring (rubber band ) seals that eat oil like it's going out of style, with around 60,000 mile on them. I find oil eating to be a more typical GM problem anyway..

Question from John (440):

I need to get my cylinder heads repaired on my '66 440.  I am going to find an identical pair of heads and have them redone (hardened seals and new valve guides/seals) then just swap.  I haven't gotten yet what numbers the '66 440 heads have or whether it  can be swapped out with anything else without dropping compression, so unless someone comes up with a better solution, I'll do with same year heads redone.  The reason I want to have my heads done is that my valve guides are shot and it seeps oil through them. Fouls plugs and cruds up my exhaust system.  How easy is it to take them heads off of my 440? I've never done it before, do I need to bleed coolant and remove water pumps, heater core and A/C etc??

Reply from Mark:

That would be best, IMHO.... Also: Be SURE to check the thickness of your replacement head gaskets. Many aftermarket manufacturers like to sell thicker than stock gaskets to lessen the chances the hamfisted will end up with leaks. Problem is, thicker head gaskets lower compression.  Are the heads you now have cracked? Why don't you have rebuilt the heads you have on the car now? If they're not leaking, at least you know they're not cracked or warped. Who knows what condition some other set of heads may be in.

To remove the 440 heads you will need to drain the coolant. And you will probably need to remove those little plugs that are threaded in each side of the block below the heads to drain the block. Sometimes they're bolt-like plugs sticking out, other times they're relatively flush with 3/8" or 1/2" square heads. ('66 should be the bolts.)

You don't need to remove the water pump. Or the power steering pump. The alternator? Maybe, or maybe just the top bracket. I'm not sure about the '66 heater core, but if it's the same as the '63's, then removing it makes access to the right side of the engine MUCH easier. (It's soooo easy to remove the heater core, anyway.) You'll have to remove the A/C compressor.  If there's still a charge in there, don't remove the hoses; just unbolt the compressor from where it's mounted and carefully set it to the side.

Some tips: When removing the rocker assemblies and the pushrods, keep everything together and labeled somehow so that the parts go back the same way into the same places they came out of. The pushrods wear into the rocker arms on one end and the lifters on the other, and mixing them up will cause undo wear as they mate up again.

Check the ends of the rocker arms where the pushrods rub on the valve ends.  Often, on big block MoPars (especially if they're high mileage and/or have been indifferently maintained) they can be quite worn. If so, you may need to replace a rocker arm or two (or more....). How worn is too worn is sort of a matter of judgment. Merely shiny is normal wear. If you rub it with the ends of your fingers and you're fingernail catches, weeel..... Pitted on either the valve or pushrod end? That rocker arm has got to go. Also, check the pushrod ends for pitting. Luckily, this stuff is generally easy to get at any well-stocked auto supply house, and not all that expensive.

When loosening head bolts, use a breaker bar, and WATCH THOSE KNUCKLES!!  The torque on big block head bolts is not all that high, but the break-away torque (the amount of force it takes to break loose bolts that have been tight for 30-plus years) can send your hands into sharp cast iron and steel bits that can do real damage. It's a good practice to loosen them in reverse order from the tightening sequence, but not absolutely necessary.  Make sure the engine's cold, though!

With the heads off, it might be a good idea to remove the soft (or freeze) plugs from the block and flush it out. This is a real easy job at this point, though you must take care not to get water down the cylinders or in the valley.

And, hey! With so much stuff off, why not clean the outside of the block and give it a Chrysler Turquoise repaint?!

If you've never pulled heads on anything before, set aside a day to get them off, and a weekend to get them back on and fiddle with the engine to get it
running right. If you've done this sort of thing before, you know it should take considerably less time than that. Especially if you have access to an
impact driver! (Even without one, it's possible to pull heads on a weekday evening, say Wednesday or Thursday, drop them off at the machinist's the
next day, pick them up Saturday morning, and have the car back on the road in time for the late game on Sunday.) Of course, it's better to have the
job done right than done quick....

Question from Bryan (440 with cylinder head problems):

I have a 67 Imperial coupe that has a miss; the number three cylinder fouls the sparkplug quickly and thoroughly. The car smokes and it  appears to derive from that cylinder only.  The car exhibits another odd characteristic: upon startup, a water/oil  (carbon?) mixture splats onto the concrete from the tail pipe. It is a fair  amount of water mixed with a black soot-like stuff. Does anyone know why  this is happening?


From Joe:

I had a problem with fouling plugs also, turns out the valve stem umbrellas (seals) were gone from years of heat they turn hard and crumble off the valves. The new seals cost about $25 for the good ones with wire reinforcing. A good Mopar mechanic can replace the seals by charging each cylinder with compressed air and releasing the valve spring keepers to expose the seals and replace them without removing the heads. Worked wonders on my car.

From Frank:

When an engine sits idle for a while (not used at all) the valve seals almost always dry out and crack up. Engine oil then can run down the valve stems and burn in the combustion chamber. The piston rings can also seize in place, either: by rusting to the cylinder wall so that their sealing edges, when broken free by starting, don't seal anymore; or by the rings seizing in place in their piston grooves so that they don't expand outward to seal. When this happens to the lowest ring, the oil control ring, the engine will burn oil. Ring problems require a bottom end job. Assuming that the compression is good you can replace the valve seals yourself. You don't have to take the car to a mechanic to do this job. I've done it, most recently on a '76 New Yorker. Get the best quality seals that you're auto parts guy has. (Shop around to get a quality name brand.) Tools required: Compression tester, cylinder leakage tester or spark plug adapter fitting (something that you can use to put compressed air into the cylinder); air compressor; torque wrench; valve spring compressor; common 3/8 ratchet set. You don't need a monster air compressor, the volume of air flow is quite low, but the pressure is pretty high. I used my own valve spring compressor which was nothing more than a U shaped rod, bent to fit under a dowel bolted in place of the rocker arm. The U-rod hooked under the dowel and I could press down on the closed part of the U while removing the spring keepers. Worked better than the commercial tool, which I thought was a pain in the butt to use. (For a small guy, I have large fingers and this tool gave more room to work than the tool I bought. 

1) Pull rocker arm covers. Remove old gasket material. 

2) Remove rocker arm. Mark the front/back end of the arm and the locations of each bolt. 

3) Remove and mark each push rod. They must go back into their original positions. Mark also Top & Bottom 

4) Remove spark plugs 

5) Thread the fitting into a plug hole, connect the air line and pressurize to about 100 PSI 

6) Using the spring compressor press down on the washer above the spring. You may need to use a small screw driver to remove the keeper from the top of the valve stem. (The keeper looks like a cone cut in half along its longitudinal axis.) 

7) Remove the spring assembly. 

8) Remove the old seal. It may be broken, remove all the pieces you can. 

9) Install the new seal. The intake and exhaust valve seals are different! 

10) Replace spring assembly 

11) Compress spring with tool and re-install keeper. 

12) Repeat 6-11 for the other valve on the cylinder 

13) Release air pressure from the cylinder and remove air fitting 

14) Repeat 5-13 for each of the other 7 cylinders 

15) Reinstall push rods - observe original positions 

16) Reinstall rocker arm - observe original positions 

17) Reinstall valve covers with new gaskets. Don't use sealer since it can break off and migrate through the engine. Tighten carefully to just snug down the cover against the gasket. Over-tightening ensures leaks! 

18) Reinstall plugs. (Since they're out and cheap, might as well put in new ones.) If you are a belt-and-suspenders kind of guy, you can turn the engine so that the piston of the cylinder you are working on is at TDC, preventing the valve from falling into the engine. I don't think that this is necessary since these engines have BIG valves, about 2" in diameter, which at 100 PSI of pressure means that there is about 300 pounds of force holding the valve closed. If you need to put anywhere near that much force into doing this, you're doing something wrong. [ Closing force (pounds) = Pi * r ^ 2 * PSI ] First time I did this it took probably about 3-4 hours. Now about half of that.

Question from John (440):

How hard would it be for me to replace my heads in my '66 440 Imperial Crown? The valve guides are worn and I am thinking hardened seats too. My plan is to pick up good condition '68-'70 440 heads with already hardened seats and have them re-done, then swap the ones on my engine out with the 'new' ones.. Feasible? Any special tool I'd need other than one day worth of work and head gaskets and valve cover gaskets?

Reply from Kne:

Can't think of any special tools. I'd maybe set aside two short days to do it, rather than one long day. Also, soak the exhaust manifold to head-pipe bolts with WD-40 as far ahead of time as possible. I've found that changing heads is a golden opportunity to paint the engine up really nice. Hint: aluminum foil is excellent for masking big things and large areas, you can mold it right over and around stuff.

Question from Ken (440):

What are the best set of heads you use performance-wise? I want to either get my heads rebuilt on my Imperial or find a better set. What kind are on the 1966 Imperials? I have heard of the 906's being a really good head. I was talking to a guy tonight that said he had a set of 452 heads. They had either 202 or 208 valves. I want to change to unleaded gasoline and also want a head that offers good performance.


From Nick:

The heads on a '66 440 aren't performance pieces...really small ports, and tiny exhaust valves. The following year the 440 got better heads, 915's, with some major refinements. 906's were based on the 915's, and there isn't that much a performance difference between them, especially in an Imperial application. The 452 heads you heard about are essentially 906's with hardened exhaust seats, suitable for unleaded gas. They would offer slightly better performance (you probably won't want to do other modifications like an intake or cam to reduce drivability), and would be reasonably priced. IMHO that would be your best bet...but I'm sure others have opinions on this.

From Steve:

I'd go with a good set of mid-to-late 70's heads. They have the hardened valve seats and extra coolant capacity near the exhaust port and sparkplug hole for durability. They would have the largest valves too.

Or, you could go with a set of the closed chamber late '60s heads. Good luck finding 'em.

You can't put on a set of Max Wedge heads, they won't fit. Someone on this List has a '62 or '3 Max Wedge Ply or Dodge. Those cars are about as cool as cool gets.

OR, you could go nuts and go for a set of MoPar Performance heads. <--lots of varieties there. It depends on how much work you want to do to your engine...what you are looking for as an end result...and how much $$$ you are willing to spend.

Question from Brian (440):

Can some one tell me where # 1 cylinder is on my 66 crown I think the wires are crossed.


From Bill:

Left (driver's side) front cylinder.

R: 2-4-6-8
L: 1-3-5-7

Fires: 1-8-4-3-6-5-7-2

From Demetrios:

You can also tell from the way the block is casted. One of the banks is more forward than the other. THe leading cylinder of that bank of cylinders is always number 1.

From George:

All Mopar V8 motors have number one piston at the left front ( side opposite the Gen so there is no confusion ) and that bank runs 1 3 5 7 the other side is 2 4 6 8 ( Gen side ) the fireing order is 18436572.

Question from Kerry (440):

I need to change my valve seals. Since a 440 does not have bolts that the rocker pivots on, HOW does one compress the valve spring with the head on the car?


From Roy:

One way to compress the valve springs is by using a used/junk rocker shaft...and a homemade spring compressor made out of a crowbar with an old rocker arm welded to it as it's "pivot point". The "crows-foot" end should be fabricated somewhat so that it clears the valve keepers while still compressing the retainer and spring. I have seen one used a long time ago and it looked like it worked quite well. Another way is to buy the factory tools that were recommended for the job by MoPar.<good luck> The #'s are/were C-3906A and C-4228. One of them is used to grab the upper and lower parts of the spring and compress it. A thumbwheel in the center of the tool is used to compress/decompress the spring.

From Brad:

You can get one of these valve spring compressors from Sears or and reputable auto parts store. I got one from Sears a few years ago. It's smaller than my hand, actually, it's about the size of a pack of smokes. As written below in a previous post, little jaws grab the upper and lower parts of the spring. A thumbwheel screw compresses the spring. When it's compressed far enough to get at the keepers you can pull them out with a magnet. The whole operation's pretty straight forward. Pull the whole rocker shaft (rockers, bolts, keepers and all as a unit) off the side your working so ALL of the valves are closed. Pick a cylinder and pressurize it (do you have an air compressor?). You can buy an adapter to screw into the spark plug hole to do this. Start at one end and work your way to the other. Compress the spring, pull the keepers, remove the spring, pull off the seal, push on the new seal (CAREFULLY, don't push so hard your force overcomes the air pressure and you lose the valve. The head will come off of course if you do this. Most valve seal kits come with a sleeve to aid in their installation.), reinstall the spring, install the keepers, decompress the spring, move on to the next one. When you're done with that side, reinstall the rocker shaft assembly. Be careful to ensure all of the pushrods align properly with their appropriate rocker. Follow the FSM and tighten the shaft bolts slowly, a little on each bolt, until the proper torque is reached. This job is really pretty simple. It just takes a lot of time having to keep doing all of those little steps.

From Kent:

Brad wrote to Kerry about replacing valve seals on a 440. Brad's advice was good and clear. However, I would like to add some advice, if I may. If you or anyone doing this would first bring each particular cylinder piston to top dead center or TDC, the likelihood of loosing any valve into the cylinder bore of the block can be prevented, as the valve can't fall any further into the bore but the top of the piston. You can find top dead center by this method. Starting with the firing order, all 66-72 V8's are 1-8-4-3-6-5-7-2, according to my reference. Start with #1 at TDC. Rotor on distributor should point to the appropriate plug wire on the corresponding contact of the distributor cap, in this case #1. Engine pointer should be pointing to the TDC mark on the harmonic balancer and pulley. The #1 piston is now at TDC. Mark the balancer in 1/4th's with chalk or whatever is readily visible to you and can be easily removed when you are done, if you wish. Double check to verify that the rotor is pointing to the #1 plug wire. Rotate the engine crankshaft clockwise, as you are facing the engine, 90 degrees or the three o'clock position which is #8 at TDC. Using a remote starter switch here really helps. Next, rotate crankshaft clockwise 90 degrees or the 6 o'clock position. You are now at TDB for #4. Rotate crankshaft another 90 degrees or the nine o'clock position, the piston in the firing order should now be at TDB, in this case #3. Again rotate the engine clockwise another 90 degrees to the #6 piston at TDC which is now the 12 o'clock position. The rotor should now be pointing to the #6 plug wire on the distributor cap. Imagine the harmonic balancer and the pulley as a pie and divide into 1/4th's or 90 degrees. If you start with #1 and rotate clockwise one complete revolution you would then be at TDC for cylinder #6 and so on. After two complete revolutions of the pulley mark, you're back to piston #1. When the piston is at TDC, slowly pressurize the respective cylinder your working on. Leave the pressure on. You have to have the piston at TDC for that cylinder or the air pressure can force the piston down and cause the engine to rotate over, causing the pressurized piston to now be at BDC or Bottom Dead Center. If the engine should rotate from the air pressure, readjust to TDC for the cylinder you are working on. Now remove the valve springs as Brad suggested. If the valve should slip and fall into the cylinder it can't fall any farther than the top of the respective piston. You should be able to pull the valve stem back up again. This could save someone from removing the cylinder head to retrieve a lost valve. There are many engine rebuild books available. Purchase one, take the time to read it, then have fun working on your project. If in doubt check it out, or have a mechanic do it. Hope this helps, so you can have fun working on your own car. Watching someone do this first maybe the way go.

This page last updated August 24, 2004.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club