I was wrong. Heads and pistons were the same. info from: http://www.nhra.com/tech_specs/engine/ Specifications for the 1971 Buick engines H.P. Disp. C.R. Ind. Make Model/Transmission Manifold R.R. Lifter Head cc 230 350 10.50 1-2 Roch 2GV-7041143/SM 7041142/AUTO 1236402 1.55 H 50.0 Specifications for the 1972 Buick engines H.P. Disp. C.R. Ind. Make Model/Transmission Manifold R.R. Lifter Head cc 155 350 10.50 1-2 Roch 2GV-7042143/SM 7042142/AUTO 1238643 1.55 H 50.0
Actually, I don't know where they are getting 50CC for head volume, but it was 58 CC on ALL 350's, before 75.
so then is the agreement or conclusion is that it was not a difference in heads or pistons, but emissions control and reporting net instead of gross?
I've posted this before: Cope&Paste mode on :laugh: In 1971, the entire American automobile industry changed the way it rated horsepower. The older system, called brake or gross horsepower, was measured without a transmision attached to the engine. The engine ran open exhaust and was free of power-robbing accessories. The brake horsepower technique did not even require the engine to run it's own waterpump let alone a alternator, airpump or power-steeringpump. In 1971, the Society of Automotive Engineers (SAE) method for measuring net horsepower was adopted. Following SAE procedure J245, the engine was now required to run the test with all power accessoires, muffled exhaust and the transmission and torque converter in place. The combination of lower power fromless compression and a different way to rate power was a shock to car enthusiast throughout America. The 454 Chevy that used to carry a 390 brake horsepower rating, now had a 285 net horsepower label. This can be read as more than a 100 hp loss, unless you are careful and knowledgeable. Likewise, the 300 bhp version of the 350 with fourbarrel carb was now packing at just 175 net hp.
