Im lookin at the specs on the 72 351 and comparing it to that of the 71 and its rated at 180(ish) hp and in 71 it was around 250. i saw that they messed w/ the compression a lot so is most of that hp lost in the heads and cam they put in the 72?
4v closed chamber heads to 4v open chamber heads. Dropped the compression sharply. Also heard mention of installing the cam about 4 degrees retarded, but have not been able to confirm that, it is a point of sharp disagreement.
Also need to find out the exact year they changed the rating system from unload to loaded motor with exhaust and accesories to calculate advertised HP numbers.
In 72 the HP ratings were changed from gross (with no accessories) to net (as installed with all accessories). Compression ratios were also lowered to conform to new smog standards. The biggest change to HP though, was caused by the rating change.
what happened in 72?
