Valve Cover Gasket Sealing Issue

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Franko

Franko

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On my 340, I replaced the heads with 1.88 valves with 1971 heads with 2.02 valves. I was going to use the Felpro cork gaskets from the gasket kit, but I noticed that both heads seem high in the center, so when I push on one end of the valve cover the other end has a gap.

Has anybody else encountered this situation? If so, did thicker gaskets solve the problem and which ones work best?
 
sure the valve cover isn't hitting the intake??


i liked the reusable valve cover gaskets from MP
 
I usually use the rubber with steel core reusable gaskets.
 
2 things are at work:
1) Sheet metal valve covers are usually warped/bent. Try to straighten them out.
2) Most stock heads are left "as-cast" on the valve cover rails. Some are a lot worse than others. Not much you can do.
No guarantee these will "fix" the problem, but I always use 93050 Moroso Perm-Align gaskets now.
 
I always use the cork rubber with stock covers, and rubber with cast alum covers. Like was mentioned above if your running a aftermarket intake they usually interfere with the v/c
 
Have you "looked" to see what may be hitting and making it "rock" back and forth? You need to find what is causing the problem if you are going to solve it correctly....
 
The valve covers are not hitting the intake. I put a straight edge on both heads and both ends of the valve cover rails are lower than the center. I would have never thought that was possible.

I think I will research which of the recommended gasket sets are the thickest and get those. I hate to start bending the valve covers, which worked fine on the prior heads, unless I have to.

Thanks for your help guys.
 
Could any of the inner baffles be hitting on the rocker arms etc???
 
I was told to glue two cork gaskets together to stop leaks. According to the member that told me it solved his leaking valve cover problem. I am willing to give this a try to see if it works.
 
The Moroso 93050 gaskets I love are .172" thick. I doubt if you'll find anything much thicker than that. No glue, sealer, etc... required.
 
I find very few applications where cork suits me today. It is a old school material.
If the rocker covers are sitting on top of something inside ( baffle interference ) no gasket material will cure it.
 
Franko said:
The valve covers are not hitting the intake. I put a straight edge on both heads and both ends of the valve cover rails are lower than the center. I would have never thought that was possible.
Click to expand...

As previously mentioned the castings were not straightest in that area.

Just thinking out loud here, but when you torqued the heads, you did start in the center working your way out toward the ends alternating as you go, correct??
 
Franko said:
The valve covers are not hitting the intake. I put a straight edge on both heads and both ends of the valve cover rails are lower than the center. I would have never thought that was possible.

I think I will research which of the recommended gasket sets are the thickest and get those. I hate to start bending the valve covers, which worked fine on the prior heads, unless I have to.

Thanks for your help guys.
Click to expand...


One day I decided to put fabbed covers on my engine and ran into the same thing as you did, but I don't think anyone believed that it was the heads when I mentioned that problem either.:D

As you mentioned, I could push down on one end of the covers and the other end would pop up about 1/4 inch.

If you take another set of the rubber gaskets and cut about the last 4 inches off each end, then attach those peices to on top of your full gasket with black RTV and press them down and allow to dry.
The next day use a 4.5 grinder (or moto tool) and taper the sharp edges where they come together, then assemble as you normally would.
Personally I hate thicker more likely to seep gaskets, and will do just about anything to avoid them.
(besides, I don't think a thicker gasket would do it with 1/8 gap on each end.)

Kind of a pain in the butt but it works. :)


This is the idea, and how it still looks today and was before I put the headers on.
 

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Have you tried to put the valve covers on a flat table to see if they rock or are flat?

So you have a spare set of valve covers that you may test fit to see if they do the same thing?
 
krazykuda said:
Have you tried to put the valve covers on a flat table to see if they rock or are flat?

So you have a spare set of valve covers that you may test fit to see if they do the same thing?
Click to expand...

I know it's kinda hard to beleive, but I put a straight edge on my heads and it was a full 1/8 inch or so gradual rise from the ends of the heads to the center on both sides of both heads.
 
Not hard to believe. Mopar left those rails "as-cast". I guess they assumed that the sheet metal valve covers would conform to the lumpy shape. They apparently did, but 40 years later it's anyone's guess. I still think that the Moroso 93050 gaskets will probably solve your problem.
 
My valve covers are stock 1969 steel valve covers and are straight. The heads are 3418915 which were stock on a 340 dated 1970 (with 2.02 valves) and were originally installed in a 1971 Duster. One head had a O cast in it and the other a U. Probably none of this is relevant, but I thought I'd mention it just in case it is.

I torqued the heads in the correct sequence and the inner baffles are not hitting the rocker arms.

As I stated, I put a straight edge on both heads' valve cover rails and the center of each is higher than both ends. As stated above, the explanation must be "Most stock heads are left "as-cast" on the valve cover rails and some are a lot worse than others."

Today I ordered the 93050 Moroso Perm-Align gaskets, as recommended.

Thanks for your help.
 
Franko said:
My valve covers are stock 1969 steel valve covers and are straight. The heads are 3418915 which were stock on a 340 dated 1970 (with 2.02 valves) and were originally installed in a 1971 Duster. One head had a O cast in it and the other a U. Probably none of this is relevant, but I thought I'd mention it just in case it is.

I torqued the heads in the correct sequence and the inner baffles are not hitting the rocker arms.

As I stated, I put a straight edge on both heads' valve cover rails and the center of each is higher than both ends. As stated above, the explanation must be "Most stock heads are left "as-cast" on the valve cover rails and some are a lot worse than others."

Today I ordered the 93050 Moroso Perm-Align gaskets, as recommended.

Thanks for your help.
Click to expand...

I believe you :D
The castings are never flat and some worse than others.
Stamped covers can flex some and seal a little better. Cast or fab'd covers wont.
For me it's a standard operation on SBM/BBM to mill the rocker rails flat so they don't leak like crazy. Only way to fix it.

100_8287.JPG


Milling the rail-
100_8292.JPG
 
I wish the machine shop that rebuilt my heads had machined the valve cover rails, but it is too late now.
 
Franko said:
I wish the machine shop that rebuilt my heads had machined the valve cover rails, but it is too late now.
Click to expand...

You can bet any heads I might swap out for will be checked and/or machined.
 
RustyRatRod said:
Nice work ^^^^
Click to expand...
Thanks Rob

I've seen a few threads about valve covers not sealing or breaking ears off the corners of the BBM and the quality of the covers gets blamed. This is the real problem, the valve cover rails on the heads are never cast very flat and the covers snap when you tighten down the bolts because the cover doesn't flex.
I doubt your average engine shop can setup a head to machine the rails flat in a timely manner, so they don't even offer it. That's too bad, customers get REALLY excited when they learn they can use their expensive valve covers again and not have them leak.
 
Just for the record- this picture shows my 1/8" gap.
 

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