Catalina 400 with 14 heads
I have a motor that appears to have come out of a 68 Catalina - 400 with 14 heads. According to my research this was a low compression motor that produced only ~265 hp. That said the previous owner setup the tri power on the car and might have done a cam as I cannot find a vacuum leak and am only getting 11 - 12" vacuum. (Car idles like butter and pulls hard to 5k.)
My question is how did standard GTO 77 head gain ~100 hp over the 14? According to Wallace Racing's compression hp calculator , the increased compression of the 77 head certainly should not have been that much. The 77's had 1.92/1.60 valves and 10.5 c.r., whereas the 14's had 1.96/1.66 valves and 8.6 c.r. I've been told that the heads for the most part are all the same (minor differences), with the exception of a few special high compression heads. So does that mean the original cam in this motor was a stump puller? Can much (50+ hp) of the "lost hp" be gained by a better cam?
Thanks in advance!
1965 GTO Convertible 3 speed tri-power drum brakes originally
400 cu in with tri-power
4 speed Muncie