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"so here's what its looking like, 273, with later model light rods, swirl port heads milled 0.05 and ported to a stock 360 four barrel intake, maybe 2.02 and 1.78 valves."



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im surprised im plowing new ground here? i really thought someone had been down this road and would share their knowledge, the valve size was intended to be more a question, but yes talking out loud here may need more clearance cut then could be sustained,



273 Std bore is 3.625, combined valve dim is 3.8, that would be fairly new ground.

Rather then just bore the 273 .060, I'd go .285 over.

I have in one of my cars a warmed over 273, I am very surprised at how peppy it is for a 273, but if great mileage is any concern, mine would not make you happy, and I would never build one.



Lol... 273 bored .285 over...

I'm curious what the Trans AM guys racing the 273's in Early A's did to their engines. Probably a lot of custom work.