The Stovebolt Site Forums The Shop Area Engine Shop 235 Valve cover gasket

Stopped in a NAPA store yesterday to check on a new valve cover gasket for my newly acquired 235. Found out there are two sizes, a 5/32” and a 7/32”. Which one should I get? I’m leaning towards the thicker of the two.

I’m curious why there are two different thicknesses?

Most likely your question is about a new/replacement valve cover gasket?

My guess is the reason for two sizes/thicknesses is to help with warpage/lack-of-levelness in the valve cover?

Load spreaders are a good thing to include in the swap.

Overtightening the thin metal valve cover is a typical source of leaking.
Using spreaders help.
I straighten my valve cover before using a new gasket.
It is the nature of real cork to oil soak a little in order to seal.

One of the most discussed topics:
https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1078707

Silicone instead of cork:
https://realgaskets.com/product/csc1-side-cover-gasket-6-cylinder/

spotbiltxo Would go with the thick one for warp reasons as was said. I like to put a thin coat of gasket maker on the gasket then wash the head flat surface clean and dry .Put the gasket on so it is like a dam to the oil then tighten the cover while the gasket maker is still pliable. If you don't put gasket maker on the top gasket surface may be able to take it on and off when needed. But of course it will soak up oil worse so your call . My .02 cents If you wait overnite before starting so your stuff can set up may not get oil soaked as soon .

buoymaker Ever have a neoprene gasket ?? It'll get slimy like an eel so you can't keep it under the cover one of those was enough. Never did try to glue it down though,that might have worked better.

Also learned not to use indian head shellac especially on the side cover,hard to get it off and hard to scrape clean,lot of loose cork to get in the engine

If anyone has used silicone valve cover gaskets on their Chevy I6 and have found it not to work well, now is a good time to share details of your experience with the forum. I for one have only used cork because that was what was available at the time.

I remember seeing folks talk “about” that silicone gasket, but had hard time finding anyone with an actual report on how it performs.

I’d like to know as well.

I used one on this motor. You have to look but it’s there. It worked fine. I changed back to a cork only because the orange clashed. That, and I did not have a purse and shoes to match.

I have a silicone valve cover gasket on my '53 engine (2 acorn nuts on the top style).
You won't get away with a deformed valve cover with this gasket. You will need to do tin smith work just like the cork gaskets require. I did glue mine to the valve cover to keep it from squirming around on me. It seals nicely and comes in handy for taking the valve cover off for adjusting the valves.
What we really need is a tutorial on how to do the tin smith work on the valve cover.
I can provide a few things I have picked up on for the 2 acorn style valve covers.
1) Put the valve cover upside down on a smooth length of 2x6. With a long extension and a socket which matches the underside of where the acorn nut hole is, mash the sheet metal there until it is restored to its original position. This area gets deformed a bit every time you put the valve cover back on.
2) Take the bow out of the middle of the valve cover on both sides where it meets the head.
3) Put the valve cover on the head and check with a feeler gauge where you can to check for gaps which require more tin smithing. One side of the '53 and earlier valve cover has a lip on it, preventing the use of a feeler gauge. You can check the sealing edge on that side with a straight edge on the bench.

'54 and later valve covers require some tin smith work at the four bolt holes, as they get deformed real easy. You can put the cover on the head and check for gaps with a feeler gauge all the way around. Then tweak imperfections as needed with a SFBH. (small -------body hammer for those scoring at home.)

If you have some 3/32" aluminum and a saber saw with a metal (hacksaw tooth) blade, you can make some great spreaders. Just make a template from cardstock or cereal box, cut and drill the aluminum, bend each piece down a bit at the center and you won't have to worry with leaks. Make certain to straighten the valve cover surface well.

Nice home made spreaders Jon!

I’ll go with the thicker 7/32” gasket and will be sure to straighten the valve cover as best I can. I also learned not to over tighten the 4 screws. Doing so mashes the cork so it doesn’t seal good.

Thanks everyone.

Personally I glue the gasket to the head. The additional height of the gasket acts like a mini dam helping to keep oil contained within the valve area.

Chuck, I like the 7/32 gaskets too.
I've had really good luck over the years with valve cover, timing cover and pan gaskets..... after installing and running it a few days go back and give the screws a "tweak" and that should "set" the gasket. Especially on total rebuilds.

Ever so often, when changing the oil on my vehicles I will "snug", just a little, the gaskets mentioned above. A '76 with 200k, and a 2000 Silverado with 326K and never a leak on the carport or ground....maybe I'm just lucky?!

Alvin, how do you know if there's any oil in them if they don't leak?

Thanks Chuck, I've wondered for years why nobody ever produced spreaders like this commercially. Since I made these I've seen no evidence of oil anywhere around the cover. They stretch from end to end all along both sides. Guess there's not enough demand these days.

One of my neglected task list items is to get some of the cheap, commercially-available SBC style spreaders and grind them down to fit.

All the ones I’ve seen are too wide to fit the 235 cover. They’re like 3/8 and something closer to 3/16 is needed.

I’ve also wondered if some studs in the head might be better than screws. Just to keep everything from walking around. I also “glue” the gasket to the head but I’ve got some seeps that need corrected.

Dragsix I don't want you to see under my hood !! That is a well done engine,beautiful job !! I am however proud to have fixed a noise (bearing) with -.002 main brgs. rolled in in the truck !!

Actually GM made spreaders for the Corvair. It's where all the aftermarket ones got the idea. American Motors had a channel at the bottom of the cover where a neoprene gasket fit on edge in the channel. Sealed very well.