Pampered-Z

Engine is a LT1: 385 CI, -12 pistons, zero deck, LT1 worked heads, the cam is 550 lift. (also a manual trans)

I was running cometic .55 gaskets, mainly to get the piston to valve clearance of .95. ( Manual = possible missed gear, so I like a little extra clearance ).

I'm doing a rebuild and was planning on going to the cometic .75 gasket because I think due to the zero deck and milled heads my compression is a bit high.

Does anyone see anything wrong with using that thick a head gasket? Would there be any adverse effect to worry about?

If I add .20 to the P-T-V clearance, if I go to a 570 lift, given the same duration and LSA does my PTV stay .95.

blue 79 Z/28

using the bigger gasket isn't a big deal in boost apps, the added quench distance isn't nearly as important as an n/a engine, there is alot of turbulence in the chamber under boost. theres some good reads over at speedtalk.com, just search it.

rskrause

Don't give it (quench) much thought for a blower application.

Rich

Pampered-Z

Thank you!

engineermike

The stock Neon SRT-4 pistons run 0.340 clearance to the cylinder head.

blue 79 Z/28

.034?, 1/3rd of an inch wouldn't work too well

engineermike

Nope. It's 0.340". As in nearly 3/8 of an inch.

rskrause

I have a friend with a boosted SBF running at 0.250" with no issues.

Rich

boosted-lt1

Wow! How much does tight quench have to do with efficiency at lower rpm's and engine loads?

Can anyone comment on why even an OEM would leave that much to be desired above the piston deck? Longer rod could be possible. Maybe they were constrained by the CC volume and had to do that to hit their CR while keeping a tough piston? Just a wild guess.

Thanks,
Scott.