diffrent heads?
 

ok the numbers on the heads are diffrent so i looked them up one is a 1.75/1.5 the other 1.9/1.5 so i pull the heads off and measure the vavles
they both are at 1.9/1.5 ?


what the....

Re: diffrent heads?
 

Possible the one had larger intakes installed. Hopefully the throat below the valve was opened up. Otherwise there would be little benefit to the larger valves.