307 engine any good?

[josh0237]

So I came across a Blazer for sale locally that piqued my curiosity--it's got a stock 307 engine, which I've never seen in real life before. How does it compare to the old standby 350? Noticeably better mpg? Noticeably weaker performance? What about finding parts? I know Olds/Buick used a 307 but it seems like that's a whole different animal.

Anybody have experience with the K5 307?

-Josh

 

[76zimmer]

that crank is 3.25...same as a 327...even though large journal only, hang on to it, or try to get some $$$ out of it.

 

[Colotow]

It was a 1968-73, 3.875 bore (same as 283) x 3.25 stroke (same as 327) 2.45 main/2.10 rod 2 bolt main.

Don't remember much about them, friends had them here and there when I was a teenager, I never owned one. don't remember being impressed with them.


some block casting #'s of them
391436
3914635 (200HP)
3914636 (200HP)
3956632 (200HP)
3970020 (115, 130, 200HP)
3970024

That's what my little casting number book has to say about them anyhow

There's another "307", as well, a factory 302 bored .030 over, complete different animal!

 

[KansasTwister]

have one in my 70 chevelle, peppy little beech even with the stock 2 barrel. Throw a 4 barrel Q jet tuned right on and enjoy it. Nothing spectacular, but it will get you from A to B, but not a race car by any means. Never had one in a truck though.

 

[Yukon Jack]

My 69 K20 had a 307 from the factory. They actually have good low end torque but beyond that they are not exceptional. Mileage is about the same as a 350.

 

[Bama72]

I was not impressed with the one I have. At high rpms (5500) I had a wrist pin break and I did a complete rebuild. At around 20,000 miles after the rebuild the crankshaft broke in half while I was going through a mudhole. Now it sits in my shop and I robbed the brackets and pulleys off of it when needed. I replaced it with a 350 that I built and that motor has close to 200,000 miles on it now. I think the 307 has oil flow issues.

 

[toomany]

I think the 307 has oil flow issues.

It shouldn't. It's based off the same SBC platform as any other Gen1 small block. There are millions of them out there without any oiling problems.