Look for different pistons -- you can only go up maybe one full point by shaving the head alone. Compression doesn't go up with the 4.0L head on a 258 -- only 8.7:1 (stock 4.0L). The combustion chamber sizes are the same on the 258 and 4.0L. ------------ Date: Thu, 02 Oct 2008 16:43:26 -0400 From: Brien Tourville <hh7x@xxxxxxxxxxxxx> LPG runs best with high compression - so - a 4.0 7120 head to a stock '81 258 would require roughly how much shaving to accomplish 11 to 1 compression ? -- Frank Swygert Publisher, "American Motors Cars" Magazine (AMC) For all AMC enthusiasts http://farna.home.att.net/AMC.html (free download available!) _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list