"The 455 mule was assembled with the 7K3 heads using Corteco gaskets and stock Pontiac head bolts. With the original pistons 0.015 inch in the hole, the 96cc combustion chambers, and the 0.036-inch compressed thickness of the head gasket, compression was right around 9.2:1. The Comp Cams XE274H hydraulic cam remained from our last Pontiac dyno session.
With this combo, we averaged our best runs to obtain a peak power figure of 390 hp at 4,700 rpm and 494 lb-ft at 3,500. Note that the engine was grunting out 450 lb-ft at the start of the pull at 2,500 rpm."
This is directly from the article in the link and very close to the same specs as the engine I mentioned above that made 412hp. I do remember the 455 I saw on the dyno made more peak torque however. Early pulls were 499ft lbs and after some timing and fuel curve changes it made closer to 530ft lbs right around 3400rpms if memory serves me correctly.
Either way that's a pretty "weak" iron headed 455 build, IMHO. I built a 455 with #46 heads on it from a 350, no ported anyplace or even a port match and made 440hp and 530tq with a Crower 60919 (RAIV clone) cam in it......FWIW....
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https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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