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68speedalert · 03-08-2007, 01:14 PM

The 307 was a 283 block (the bore size) with a 327 crank (stroke size).

It was never built up for power like the 283 & 327. It was never highly thought of in the day. They always seemed to burn a lot of oil.

I always wondered why that was, since they were 283 blocks (one of bow-tie fans' favorite).

A good friend of mine is a small-block guru. He said it was because the later 307's were newer castings and that Chevy didn't let them harden enough. Therefore they wore out rather quickly. I have no way of knowing the truth, yet have no reason to doubt him.

The tremendous 302 was a 327 block (bore) with a 283 crank (stroke). It was an extremely fast high revving engine.

The 305 didn't come out until about 1976. My guess was to have something other than the straight six for the cars.

03-08-2007, 01:14 PM	#5
68speedalert Semi-Senior Member Join Date: Feb 2003 Location: Washington, MO Posts: 390	Re: 305 vs. 307 street build opinions The 307 was a 283 block (the bore size) with a 327 crank (stroke size). It was never built up for power like the 283 & 327. It was never highly thought of in the day. They always seemed to burn a lot of oil. I always wondered why that was, since they were 283 blocks (one of bow-tie fans' favorite). A good friend of mine is a small-block guru. He said it was because the later 307's were newer castings and that Chevy didn't let them harden enough. Therefore they wore out rather quickly. I have no way of knowing the truth, yet have no reason to doubt him. The tremendous 302 was a 327 block (bore) with a 283 crank (stroke). It was an extremely fast high revving engine. The 305 didn't come out until about 1976. My guess was to have something other than the straight six for the cars. __________________ '68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab Last edited by 68speedalert; 03-08-2007 at 02:49 PM.