Dave88z

Shooting for around 12:1 compression, not sure on quench. Here's what I got.
heads 62cc
piston relief 5cc
cometics .060"
gasket bore 4.130"
cyl bore 4.030
piston to deck .019 out of the hole (no comments please )

I came out w/ 11.975 static comp and .041 quench.
If my math is correct I think that is as close as I can get with the quench. If I go to a .051" gasket and a bigger cc head to keep 12:1 the quench is too tight
(.030"!)
If cometic made a .056 gasket I would be at a .037 quench-I thought that would be ideal but not sure if they make that thickness. What do you guys think?
By the way-its an iron 408 and I have not ordered the heads yet. Going with TEA TFS. I hope I covered everything-I'm sure someone will let me know if I didnt

vanilla89

iTrader: (8)

.030 quench is not to much,i'm running cometic .030 with the piston .004
out of the hole

1989GTA

From what I have read you would be better off with the smaller combustion chamber. That would help for a better burn. On the flip side I don't recall anyone building a motor with the piston .019" out of the hole. So there may be other factors at play here.

Dave88z

When the motor was built it was only a few thousandths out of the hole. The deck was somehow damaged and had to be resurfaced. After decking out the scratch and squaring the block we ended up .019" out. I guess it beats buying
and machining a new block.

Dave88z

Wow, everyone I have talked to on this forum has said not to go below .030 quench-and that was pushing it. How does she run?

GuitsBoy

iTrader: (4)

depends how far on the ragged bleeding edge you want to run your motor. If you think about heat expansion and piston rock, .026 isnt a whole lot of room.

Dave88z

.026 does seem a little close to me, plus don't you need to leave room for carbon build up.

Dave88z

Any other suggestions?

TWS

iTrader: (63)

I am not an engine builder, but am currently having one built by a shop that knows their ****. We have discussed proper quench and they firmly say the between .040 and .045 is the "magic number" for best power and efficiency.

Dave88z

Thanks man, I guess I will go with the .060 cometics. That puts my quench at .041".