wyocutlass

I am taking the heads off my engine to clean them and inspect the pistons. I am trying to keep this engine as stock as possible. If I use a fel-pro and it's thicker will I have to change out push rods to longer ones? Or is there a gasket that is stock specs?

svnt442

The pushrods won't notice the difference.

wyocutlass

Thank you

wyocutlass

One more question I'm looking at the gaskets and trying to figure which to order. There are some that are bore 4.250, 4.230, 4.155, 4.200 etc etc. Which bore should I use and is there any compressed thickness I should stay around? The engine is completely stock.

MDchanic

Why not just have the heads decked 0.030" - that way the heads will stay in the same position, and there will be no change in compression ratio.

- Eric

wyocutlass

The compression is already 10.5 to 1 so if it lowers a little by putting a thicker gasket then I am fine with that. Hard to find gasoline that will work with that compression where I live.

MDchanic

Perfect solution, then.

Your actual compression (as opposed to nominal) is probably somewhere between 10:1 and 10.25:1, and the head gasket change would probably knock it down to about 9.4:1 - 9.7:1.

- Eric

BlackGold

No, but the rocker arms might notice when they start rattling around because the pushrods are now too short. If the engine is "completely stock," that means he doesn't have adjustable rocker arms. The stock rocker arm set up only works if all of the other components are stock -- including the head gaskets. Will the raising of the head 20 - 30 mils with the FelPro gaskets really make the rocker arms loose? Maybe not; it depends on how worn all the components are. But even if they aren't loose, you will lose preload on the lifters.

joe_padavano

This is true, but the reality is that I've done a few valve jobs on Olds motors and replacing the stock steel shim head gaskets with FelPro gaskets has never caused a problem.

Run to Rund

I like, and stockpiled, the Corteco 55661 which is .028" thick vs. .040" for the Fel Pro. The steel shims are probably .017" thick.

BlackGold

One of the problems with working on 50-year-old cars is that very few of us know if an engine is really "completely stock." How many owners came before you? How do you know a previous owner didn't have a valve job done, sinking the valves a little deeper into the heads and/or using valves with slightly different stem length? How do you know the cam wasn't replaced with one with a smaller base circle? This kind of stuff affects the required pushrod length. Bottom line, if you bolt it all back together and get proper lifter preload, great! But don't be surprised if you don't.

joe_padavano

That's an excellent point, since the heads are usually off for a valve job, which pretty much includes milling the mating surface of the head (and thus at least partially negating the extra thickness of the FelPro gaskets).