whats the bore and stroke of a 307 v8 cause we are having some confusion between this and it being a 350.
thanks

 

I don't know about a 307 bot a 350 is a 4.00 bore and a 3.48 stroke. A 307 has a smaller bore like a 305. If it is less than 4.00 it is probably a 307.

 

I think they had a 3.25 in stroke like the 327,and a 3.875 inch bore.

 

It's a 283 block (3.875") with a large journal 327 crank (3.25")

 

The 307 was supposed to be an economy/ emissions motor. It had the 327's 3.25" stroke crank, and the 283's 3.875" bore.


That's information I found doing a search on this site.

 

Yep that's it. A 283 with a 327 crank. The opposite of a 302. Built for low end grunt and emissions. My dads 70 chevy shortbox has a good ole 307. Runs great and it's never been apart. 87000 miles.

 

well it seems that it might be a 327 cause the bore on the motor is 4 inch and the stroke is 3.25 but the person i bought this from said it was a 350 and we arent sure about the heads on it. how do we tell if they are 307, 350, or 327 heads??
thanks

 

Get the casting numbers off of the heads. Couldn't hurt to do the same with the block.

The factory never made a "good" 307 because of the aforementioned economy slant - weak cam, poor heads, always a 2-bbl carb. But, from a stroke-to-bore ratio aspect, it's more performance-oriented than the 305. My mods on a 307 would make more power than I'm making now.

Also, there were some pretty bad 327 and 350 heads out there. So, just being one or the other doesn't necessarily mean they're better than 307 heads.

 

FYI: there are two 307's that are commonly confused with each other.

Oldsmobile 307 used in many 1980's general motors products.

Chevrolet 307 used in some 1960's and 1970's general motors vehicles.

few if any parts are interchangeable between the two motors.

 

the casting numbers on the block say that it is a 307 but when we tore it down to the pistons we measured the bore and stroke, and it seems to be a 327. the confusion comes from the fact that the guy i bought the motor from told me it was a 350, he had put a comp cam and a 750 cfm holley on it, we couldnt get it to run right. so we tore it down and thats what we found, but im not sure what heads they are

 

Some of those old 3.875" bore blocks were bored out to 4" (was fairly common with 283s before the 327 came out). That may have been what somebody did. The cylinder walls will be pretty thin, and a .030" rebore should not be considered.

If they used 350 pistons (3.48" stroke) because they thought they were turning it into a 350, the pin location is not the same as 327 pistons they should have used (3.25" stroke, same as 307), and compression is going to be lowered.