Posted by Matt Wilson on Thursday, June 17, 2004 at 11:17PM :
In Reply to: 230 compression ratio questions posted by Scott Johnson on Tuesday, June 15, 2004 at 11:17PM :
Years ago, I took the head off my 230, and as best I could tell, the head was stock or very close to it (not much machining had been done on it). The ratio came out to exactly 6.7:1, which was stock for my year truck.
Anyway, being inexperienced and thinking I could get some more power out of the engine, I decided to have 0.080" removed from the head. The compression ratio now came out to right at 8.0:1. To my disappointment, I really could not tell any difference in power. Oh well....
A couple of years ago, when I rebuilt the engine, the machinist removed an unspecified additional amount from the head (0.010 or 0.020" he said), and the compression was up a little more. Even with a high-lift cam from Vintage Power Wagons, there was still a fair amount of clearance between the valves and head, enough to prevent them from hitting.
Hope this helps,
Matt