block deck clearance and quench area

matmaster · 11-23-2004, 10:50 AM

I've built V8's for years and the prevailing wisdom is that the quench (or squish) between the piston and head should be in the ballpark of 0.035" to 0.040" for the best results (to help stop detonation). After decking the block, my Ross pistons are even with the top of the block. My new Cometic head gasket is supposed to be 0.051". Is this too much clearance for adequate quench? Does anyone know the factory compression height (top of piston to head clearance at TDC) for the 1G 4G63? Thanks.

11-23-2004, 11:07 AM

has anything ever been taken off the head? anything off the block? what is the piston to deck clearance of block. you wont have to worry about too much clearance, its usually the other way around hehe =P

matmaster · 11-23-2004, 01:23 PM

yes, .006 off the head and .008 off the block. Pistons are at 0.00 (even with the block). With a .051 Cometic head gasket, I'm quite a bit over the ideal 0.035 quench. Is this normal?

sunflashx · 11-26-2004, 10:36 AM

My pistons sat .005 in the hole, so I ordered a .036 thick cometic gasket. Using the .030 gasket was too close for comfort for me to the short end of the tolerance range.

Seems to work pretty well. I've been really happy with the performance I've gotten from the motor.

matmaster · 11-29-2004, 01:22 PM

Sunflashx, I'm looking at the Cometic catalog page for the DSM. I only see the 0.051 gaskets listed. Do you have a Cometic part number? Thanks. P.s. The gasket I have is a Cometic #C4233-051

Cesar · 11-29-2004, 02:35 PM

I had about .003 taken off the head and about the same for the block. I used a mitsu metal head gasket which is about .057 if I'm not mistaking. The 8.5 comp pistons that I'm running balance out the comp ratio and give me a compression reading of about 165ish for all four pistons. I figure I can remove about .018thou off the head to get 180psi readings. What do you guys think??