5/16" more threads into the chamber will cause hotspots and detonation even if the pistons don't hit them! Those are 199/232 plugs, tell the guy you don't have a 232! FYI- H-10's also fit flathead Fords! You can ask for 32-53 V-8 Ford. And they fit some lawn mowers. H-18's are just a hotter heat range. amxron 70 AMX 70 Hornet 78 FSJ Wagoneer Fleet&JEEP Mgr Orbit/AMC-JEEP 50-1787 _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list