Inliners International Forums General Discussion Engines GMC 302 intake on 270 engine + carb choice?

Badsix,
CNC is right, the way to do it is measure all that stuff on your engine (and post back, the numbers would help me gathering info for the stock GMC history).
I got 118cc for the 302 head from the HAMB site.
I am GUESSING at 99cc for the late 270 (small closed) head, back-calculating from its factory CR of 7.50 to 7.75.

IF those are true, then going from 118cc to 99cc would raise your CR from about 7.50 for a stock 302 to 8.65 with the smaller late 270 head. IF everything else is compatible and I'm not sure about that.

The smaller ports might cost you 10hp or more though compared to the bigger 302 ports.

Well you can see why I am searching/guessing for all the stock GMC numbers, they are very hard to find but they matter in order to calculate anything!