I mocked up the motor tonight and came up with the following clearances:

Crankshaft endplay: .0055
rod-to-rod gap: .020
piston to deck height: .020

The one i'm looking at is of course, is how far the piston is sitting in the hole. With the Fel-Pro 1074s, I end up with a .059 quench height; not good.

-Should I zero deck the block to get the quench down to .039? Or should I just use the .029 Impy gaskets and only drop my quench down to .049 and will that be tight enough on the 8-10 lbs of boost I plan on running?

- If I need to deck the block, can I do so without distorting the cylinder bore, or do I need to have the torque plate hone redone as well?

-Tightening the quench of course will raise my compression, but i'm going to open up the head chambers from their current 52 CC to around 58; giving me 9.2 to 1 on the .029 gasket or 9.4 to 1 on the decked block option.

To summarize, which is better. 9.2 to 1 w/.049 quench (.020 deck height) or 9.4 to 1 w/.039 quench (zero deck height)?

Cheers,
John

 

Tighter quench... don't worry about the .2 of compression.

No the decking doesn't distort the cylinder bores.

Bret

 

Bret,
I dropped the block off at the machine shop this morning and already sent the heads off for additional porting. If I can get the chambers to 58cc's, I'll have 9.4 to 1 SCR and 8.5 to 1 DCR. The Quench height will be .041 with .002 still on the deck. Do you think i'll have any issues with valve to piston clearance with these -20cc pistons? With .018 comming off the deck, will I need to do milling on the head intake side for it to line up?