So lets talk about the weak point of 351C 4V cylinder heads...
Port flow balance... Intake flow typically equal to a 426 Hemi.... First ya gotta realize back then flow benches didn't pull the pressure/volume they do these days.... Going off memory the numbers for a 351C 4V head were around 130 CFM @ 3 in/H2O Exhaust flow? Equal to a Volkswagen Beetle... Actually the number I remember is 55CFM...
Back then the expected numbers for a 426 Hemi were in the neighborhood of 140 CFM intake 115 CFM Exhaust...
In order to fit the exhaust into the standard engine compartment Ford make the exhaust turn about 130 degrees in the exhaust port...
The serious racers would slice the outer 3/4" of the head off & furnace blaze on side plates allowing the port to continue upward... Not easy to find anything on the internet cause there have been aftermarket heads almost as long as theres been an internet.... But I found a few pictures so y'all can get an idea of what was involved...
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And that is your Ancient NHRA history lesson for today...
Oh, Before he dominated with a 340 with some of the very first W2 heads Bob Glidden was one of the innovators behind side plating Cleveland heads....
