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Old 01-18-2021, 06:34 PM   #30
MikeB
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Re: 1972 307 cam selection... HELP!

Quote:
Originally Posted by 68Stepbed View Post
That left a multitude of 283 blocks (3.875" bore) and 327 cranks (3.25" stroke). They were put together, and with a set of wheezy heads, they were thrown into base and low option modeled cars and trucks.
I don't know if the 307 was built to get rid of parts, or simply to make more torque than a base 283 in the new longer, wider, heavier cars.

All 283 blocks were small journal, and all 307 blocks were medium journal, right? I guess the raw block castings could have been machined for larger main bores. But the real question is how would GM have changed the casting number in a leftover block that was cast for a 283?

Also, the 307 crank was a different animal. It had lighter counterweights than the 327 crank. Again, it could have been the same raw casting but just machined differently. It would be interesting to talk to a Chevy powertrain engineer from back in the late 60s.

I think you overestimate the number of 302 engines produced. I mean, they were available only in the Camaro Z28, and only for 3 years. Whereas 283 and 327 engines were available in virtually any car or truck. I'd bet there were easily 50 times more 327s sold than 302s during those years. When I was a kid slobbering over hot new Chevys that I couldn't afford, I would see dozens of 327 emblems every day, even in 4-door sedans. Z-28 302 emblems? MAYBE a couple per month.


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Mike
1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- sold
1981 C10 Silverado LWB -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
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