What RPM effects come with the commonly used flathead cams? Like which cams shift the powerband up the tach and by how much? OEM cams check out around 3500-4000. Do any of the streetable cams carry out to 4500-5000?
I bet the folks on Fordbarn can tell you. Meantime, here's some good info. high rev flathead ford cams - Search
I found a hot rod article with a whole mess of intake dyno'd. 4 barrel, dual carb, triple carb. The 284 CID dyno engine had a H&H spec'd custom 280 advertised cam and it peeked in the hp's right around 4500 with all intakes.
The cam really isn't the major hold back on a flatty, it's the valves and configuration. My ISKY 1007b cam runs out about 4500 but pulls like a freight train in the mid range. I'd rather have torque I can use and enjoy than HP. Opening up intake valve to a larger size and you are on your way to making it better but fighting the exhaust all the way out. Porting and smoothing are two things to improve, but still, by nature they are hard to get to spin high without OHV conversions. The center port is a known HP killer on the exhaust. Good springs, some mild work, and probably any isky cam over a 88 will net you 4500, only real cams to push higher were the 400 jr and above. Making HP on a flatty is how much money you want to throw in the wind. My recommendation is to find a cam that sounds good and make a good stroker motor and if you still have money, bolt a HUFFER on top!
I firmly believe a good street engine only really needs to spin to about 5000 rpm. My daily driver is a 180hp/190ft-lb turbo 3 cylinder. I only use about 2/3's of it's hp but peak torque is around 3000 rpm and I work all 190 ft-lb all the time. But when I want 5000 from time to time, it's a little gutless. A flatty with 125-140 hp and with 200 ft-lb that I can access with a T5 would do just fine.
the fella with roadrunner engineering, which specialized in blown flatties, always liked the 400jr, but found in later days that the max1 would outpull the 400jr to 4,000 rpm.
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