skimmed head with metal gasket, while using stock 4g91 cams, still ok, but if timing too high, sometimes will get knocking sound, especially in the afternoon, or going up hill with aricon on....
skimmed head with metal gasket, while using 4g93 cams(spec forgot already. putra one?) have to set timing very carefully. cos always got knocking sound, any time in the day... timing must be set to relatively low.
stock engine head with metal gasket, i think it is ok la... but not 100% sure. cos while i was running on metal gasket and skimmed head, and stock cams. valve did not hit the piston. but the piston hits the head itself, not valve. if got chance that u see a 4g91 head, look carefull at the shape of the space around valves, u will know what i am talking about. or i take a picture and show u guys....
by the way, that day i checked my car compression. my mach told me it is around 250 psi something. but how to convert this to the normal one? i mean like 9.1:1, or 12:1. can anyone convert it for me? i really don know 250psi means what level the compression is.