A friend put me on to this web site. It talks about early GMC straight 6 engines of large cubic inches.
We are talking 360, 426, and 503 cubic inches. I had never heard of these engines. Anybody know if any of these were hot rodded?
https://www.curbsideclassic.com/blog/cc-...ly-big-gmc-six/

Lets put an 8-71 on it and stuff it in an AD half ton. Is the 503 something that can be found?

Those are BIG truck engines and will not fit in much else. The 360 is the only one that would even qualify for the vintage class at Bonneville since there is a 375" limit. Years ago I got a 413ci Dodge flathead six with the Idea of playing with it in a vintage class at Bonneville. There is a 375" version of it, just a crank change. Otherwise it would be in BG lakester and tires aline would be over 3Gs. I even had an Honest John missile nose cone for it.

I doubt that performance wise the extra size and weight would be helped by the extra inches. Maybe I'm wrong.

W/r/t "I doubt that performance wise the extra size and weight would be helped by the extra inches"

I agree, these engines have much smaller port and valve area per cubic inch than the 302 etc. and were designed to operate at very low engine speeds.

Thanks for the info.
Would still like to see one of those big ones in operation.