I had long branch manifolds with 2.5 flowmaster cross flow system on my 68 Firebird. 455, similar cam, a RPM with a Thermoquad. Turbo 400, 3.31 gears with 275/60 Drag Radials. Car weighed 3660 with h me in it.
It ran 12.10 @ 114 in Kansas in summer. Sold it to a guy in Pennsylvania. He told me he was running high 11’s there.
Edit, I’ve got oldtimers disease. 12.10’s was with headers & dual dyno max mufflers under the back seat foot wells.
It ran 12.25 with long branch & cross flow exhaust. Had Continental tight 10 inch converter both ways.
Last edited by Murf; 05-12-2023 at 04:42 PM.
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