Thread: What HP would you guess???

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I recall a buildup in a Hot Rod annual by a guy named Cotton Mather who claimed 550 HP from a blown flathead and I vaugely recall a cover picture of a flathead in the Fall of 1955 claiming 400 HP from a flathead at a time when a lot of folks were keen to install some late model OHV engine. It may be possible that a few flatheads with ARDUN heads and running fuel could have made over 500 HP but as Southerner said how long did they last? What is often ignored is the attention to beefing up the bottom end using a steel girdle around the bottom of the block and historically that sort of thing may have been behind the redesign of the Ford V8 in 1954 emphasizing the Y-block with the deep block around the crank bearings. Still having only three main bearings is a weakness, not to mention the siamese middle exhaust port. You have to remember that the average street rod in 1955 probably only had dual exhaust, finned aluminum (8.5:1 ?) heads and a two pot intake manifold and all of that probably added up to 120 to 130 HP using a stock cam. The cam was harder to change in a flathead because you had to add adjustable lifters and adjusting them required removing the intake. Among my H.S. friends most ('41) Fords had only dual exhaust, shaved heads and steel pack mufflers and that probably produced 105 HP, so even a Studebaker OHV V8 looked pretty powerful and Olds 88s were king of the road with '50 Mercs and '52 Hudson Hornets a close second, but it was clear that the OHV V8s produced a lot more power in stock form than an expensive fully built flathead. Still Pep Boys sold a lot of dual exhaust kits for flatheads and Smithy Mufflers must have made some money too.

Don Shillady
Retired Scientist/teen rodder