Re: Lets see if we can get some addl. input from our old timer 351C Ford Builders

Here ia a way to put things in a better perspective for the time that the 351c came about at Ford. Back then there were basicially just Regular Leaded and Premium Leaded Gasoline at all Gas Stations except Sunoco, which did have different grades at that time (I think 180 to 260 as I recall) but they were the only one. When you bought a car, It had either a Regular gas (meaning Low compression) or a high performance (Premium gas was necessary because of the higher compression) engine. Most 4 Barrel carb engines from Ford at that time were Premium Gas engines and most 2 barrel carb engines were Regular gas engines, meaning the higher compression 351c 4v was made to run on premium gas and the 2v 351c was made to run on regular. At that time, Ford could produce the two different versions of the 351c by just putting different heads on the same short block and simplify their assemby of engines. In the late 1960's and early 1970's, The U.S. government had a big push to control exhaust emissions I have a friend that started as an Engineer at Ford in 1973 and he said at that time all engineering efforts were on emissions and that racing efforts were all on the back burner. The government was breathing down the necks of the big Three about exhaust gas emissions and that all efforts were placed in that area. In about mid year 1971 all high compression engines were lowered because of the emissions deal and the fact that there was a push for unleaded gasoline and catalytic converters that came about in 1975. When The Government started pushing for unleaded gas and catalytic converters all the compression ratios were lowered because of removing the lead which increased the octane rating on the gas. High octane leaded gas was to be discontinued so the automakers produced everything with a lower compression ratio to run on unleaded. As far as drag racers prefering one head over another, It would all depend on the class intended. I have a couple of friends that run the open chamber heads because they are running a certain class in NHRA Super Stock and the horsepower rating with the open chamber heads is lower so they can run with less weight in the car. Some of the closed chamber head engines were refactored with more horsepower because they ran fast and make it harder to be competetive in a heavier car. The quench head engines seem to run fast in very light cars(under 2800 lbs)

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