QUOTE(jhadler @ Oct 9 2009, 08:54 PM)
Numbers from the friend who built the motor scared me into tearing it down with only 2 hours break-in logged.
Claimed 0.016 deck height. If I haven't already introduced the pistons to the heads, it's probably only a few rpm away. So at the VERY least the heads need to come off.
My thought was this: The existing deck height (I will remeasure to confirm) is way too low. Pull the heads, take a few thou off. Pull the jugs and shim them to bring the deck height up to .040. The question is: "how much to take off to reduce the combustion chamber volume by x cc's?". Right now I'm at 59 cc's. By my calculations, I'd want to get the CC down to 56 cc's. (with 0.025 base shim that should give me 9:1).
I will likely go through the bottom end as well to confirm all the bearings have the proper clearances.
-Josh2
Well, now I am confused. Are you guessing on your real numbers, or have you pulled the heads and measured the deck height?
You may be OK if you just add a shim.
If you deck/flycut the heads, you are moving the valve closer to the piston so any normal advice you get on deck height will be WRONG.
Normal advice assumes stock heads.
If you remove 004 from the heads, you just moved the valve 004 closer to contact with the piston.
I would suggest that you measure the deck height on every piston first.
Then CC every port in the heads.
Match the heads, thats it...do as little decking to the heads as possible and make up your difference with base shims (which are cheap and can be changed easily if you measure out to small.)
Rich