305 vs. 307 street build opinions

[Zoomad75]

My 69 Nova came from the factory with a 307. It was an absolute dog due to a couple of burnt valves. I did a quicky valve job in High School Auto shop and started bracket racing. A 307 2bbl with 2.73 gears at Denver's altitude is no ball of fire, but amazingly consistant. I was able to shave 3 seconds off (no kidding) by swapping out the wheezy 2bbl for a well tuned q-jet. Due to the high gearing it just didn't have the pull out of the hole, but would cruise at 80 turning barely 2000 rpm.

The poor tired 307 was a good economy engine but even in a light Nova, no power house. I couldn't imagine a 307 in a truck without some bolt ons for help.

Might want to keep in mind that there were two types of 307's. The early 67/68 had small journal cranks while the 69 and up had the large journal cranks (same size as the 350). 302's and 327's made the change to the large journal cranks at the same time.

I can totally understand rebuilding a 307 for restoration purposes, keeping a truck numbers matching and all that. Rebuilding a 307 for performance is a waste of time when 350's are pleantiful and still cheap. The cost to do the same mods to a 350 is the same and you would yield more power. Better bang for the buck.

I'm not against anybody building one to be different with the performance mods listed above, its your choice. Just don't expect the same output as 327 or 350 with the same mods.

One other note that one touched earlier...The 307 blocks are said to be low in nickel content. Meaning accelerated bore wear on high mileage engines. Sometimes you may not have enough meat in the block to bore for oversized pistions. Might need sonic checking.

By the way, anybody that wants my old 307 can have it. It's in Denver if anybody wants it.

[68speedalert]

Originally Posted by Zoomad75

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One other note that one touched earlier...The 307 blocks are said to be low in nickel content. Meaning accelerated bore wear on high mileage engines. Sometimes you may not have enough meat in the block to bore for oversized pistions. Might need sonic checking.

That's what he told me.....thanks for the refresher.