buzz12586

If I run a stock thickness headgasket and stock heads (just cleaned up) would my compression be too high for a street motor?? I will be running a cc503 cam if that makes any difference.

roadtrip120

no, prob not even over 11.0

buzz12586

It says that with 64cc heads the compression is 10.6:1. I believe the LT1 heads are 54-55cc. Wouldn't that make it higher than 11??

seawolf06

There are a lot more variables. Those numbers aren't LT1 specific at all. Go with the felpro gaskets. Your compression definitely won't be too high as long as you use good gas.

buzz12586

Yea we have 93 here and thats what I use all the time. Is the FelPro gasket you are referring to the 1074 gasket?

Denny McLain

Stock is a street motor designed by GM. Think your a bit confused or I am.

If you keep everything stock nothing will change from factory specs...... yes a cam does make a difference. More duration on the same lobe seperation usually lowers your dynamic compression. Static and dynamic are different as static does not change, dynamic does as takes cam timing into the statement.

Currently @ 12.8 to 1 compression and have ran as high as 13.3 to 1 with no issues. Don't be afraid of compression, it's your friend.

Normally the deck (height of piston to top of block) is about .025. It really should be checked but I'd run a much thinner gasket than stock as your quench (distance from the top of piston to bottom of head) will improve, your compression will improve and your car will run more efficient. Lingenfelter in his book recommended a .043 quench but we now find you can run a much tighter quench and get away with it. Think I'm @ .038 or very close.

Put a .029 or a .024 on it and not the .049 as you will just pick up free hp. Should be good for about 5 hp.

Z-RATED94

So Denny, are you saying the valve reliefs are the same cc's in the stock pistons and the Mahles? Thanks, Rick.

buzz12586

Yea that was my question as well.

SS MPSTR

you can run it tighter than that too. my new 385 is at 0.030" quench.

Denny McLain

To be honest I wasn't thinking about valve reliefs when I did the post but did think of it afterward. Guessing without doing any research the valves reliefs are a little larger than stock pistons to accomodate larger valves and more lift but that would lower the compression even more.

Denny McLain

My wife didn't know I rebuilt the engine (sometimes you got to do those things) and didn't want it sitting for a month at a shop waiting to be decked. Screwed up and didn't have the block decked like I should is the bottom line. Instead used .024 gaskets which gave me a quench of about .047. Wasn't in love with that, but not completely out of the ballpark.

Just installed a set of .015 gaskets and still not jumping for joy on a .037-.038 quench, but it's better than .047. I'd probably be running about same as you if I had done it right in the get go as it sure makes one run more efficient.

Really amazes me how much better and more knowledgeable everyone is getting. I just love it!!