The 302's were brought about to meet cubic inch limits in Trans Am road racing. Or for a particular class with that association. Boss 302 Ford, the 304 AMC AMX, etc.
Chevy's was a basic 4" bore 4 bolt main 350 block fitted with a 3" stroke rather than the 3.48" of the 350. The cams, heads, intakes and carbs were common too or very similar to all Chevy HP small blocks from 65 or so till then. The best they had at the time. They were rated at 290 horse power from the factory. But everyone knew that was BS, a scheme to help owners with insurance cost. The 302 had one very common problem in stock form that most were aware of & that was spinning rod bearings. Chevy had increased the diameter of the crank shafts & the earlier rods were a bit too thin causing stretching. The high revving capabilities of the 302 was also part of the extra stress..
Not all 302 Chevy's spun bearings & they were fast for their size. They were built from 67 to late 69. Trans Am changed their rules & Chevy already had a 370 horse 350 & I guess they saw no reason to continue the smaller one.
The Z/28 was the only model to get this engine & it was available with no other, from 67-69. The 70 1/2 Z received the 360 horse LT1.
Are you sure that's how it went?
The 1967 302 had the small journal 3" stroke crank, a ala the 283, and carried the same small journal rods with 11/32" rod bolts. That's where stretching at high rpm occurs.
When the crank journal increased in diameter the rod bolts increased to 3/8" diameter.
