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350 Crank in a 307?

I was told in my 69’ camaro that it has a 307 matching numbers but now that i have my engine out to rebuild it the crank went to the machine shop and was told it was a 350 Crank. Could this be possible? What engines have the 350 crank in them?

My engine book shows the 307 was essentially a 283 with a 327 crankshaft. Maybe the crank is actually a 327 or the engine is actually a 350.

If you can post some block casting numbers and cylinder head casting numbers I’ll be happy to decode this and see what’s going on.

Here’s a good article on the different SBC variations:

I guess it could have the 350 crank, but that’s not a normal combination. You’ll want to check the bore, see if it’s not a 307. Do you know for a fact that it’s “numbers matching”?

The beauty (or bane) of the small block Chevy was that you could interchange so many parts between the 307, 327, and 350 that you may have parts from all three of these engines together in yours. If you’re building a show car that needs matching numbers and documentation, you’ve got some work to do. If you’re building a car that you drive and enjoy, who cares what’s inside the block? Only you will know.

Ok some numbers I pulled off the block are 373, G16, T, 388, T21, CONV1, 3932388 And the cylinder bore is 3.985 or something close to that not a 4 tho. No I don’t know for fact the guy that traded me for a vet said it was so no idea lol

Was the 307 even available in 1969??

Yes it was used in the RS models like mine is

My book shows that casting number (3932388) is either a 350 or possibly a 302. There’s a little murkiness there due to the 388 and a 386 number but the 307 block show a different casting number altogether.

Have you tried decoding the VIN plate on the car to see what the car was born with?

It could be that that whoever told you it was numbers matching was just flat wrong or (hate to say it) lying. “Numbers matching” comments should always be taken with a grain of salt, even on those 100k dollar Barrett Jackson cars.

I will put my vin on here tomorrow but the thing is that the 302 and 350 both have a 4inch bore and mine doesn’t quite have 4

The standard bore on a 307 would be 3.875 and you state this one is 3.985. This would make it the mother of all overbores, which would seem unlikely.

How is the bore measurement being taken?

Everything I’ve got shows that casting number makes it a 350 or 302 with the former being far more likely as the 302s are probably all 4 bolt mains.

It was a rough guess with a tape measure I don’t have a Mic to measure it lol. And it was across the cylinder in the middle. But yes it is a 4 bolt main. I’m pretty happy with a 302 as I have been told its a pretty bad ass engine. BTW can u have a 350 crank in with that?

302…4.00 X 3.000 (Trans-Am engine)
305…3.750 X 3.480
307…3.875 X 3.250
327…4.000 X 3.250
350…4.000 X 3.480

Numbers Match…Right…But what do they match??

I was told numbers matching car and engine but its looking like thats not the case.

I was told numbers matching car and engine but its looking like thats not the case.

Don’t rule out non-matching numbers just yet. There were some changes around this time and often some of the VIN numbers (not all of them) are present in the engine code numbers. This matches the engine to the car as it came from the factory.
Suffix codes show “D” type codes for the 307 and “H” type codes for the 350.

A tape measure will not be effective when measuring bore sizes unless it’s astronomically different and seeing as how the bore is around 4 inches and there’s 4 bolt mains you likely have a heavy duty 350 and that ain’t bad. The only engine more desireable would be the 302. (Short of the Yenko, COPO cars, etc)

If I owned a '69 RS with a 4 bolt 350 I’d be dancing in the streets and keeping the neighbors up. You’re one lucky dude.

To the best of my knowledge the 307 was available starting in 1968–it was the base V8. Not a bad engine in my opinion.

I’ll just be happy to find out what it is. Lol but yeah 307 was one of the worst engines Chevy ever made is be happy with a 350 its more of the common engine plus more HP and the 302 is a nice high reving engine

It has a 350 crank, and sounds like it has the 350 bore (4" within a whisker), so I bet it’s a 350. Actually a good thing, that’s the one to have for lots of compatible and cheap parts.

Yeah that’s what I was thinking too. But kinda disappointed its not the original engine that came with the car

The small block Chevy has to be the commonly swapped around engine that has ever existed along with head and manifold swaps, etc.
Kind of like the old Harley motorcycles. A '37 transmission in a '55 frame, '62 engine is a '47 frame, etc, etc.

At this point you’re assuming the car came with a 307 from the factory. Maybe the 350 is the actual engine that the car was born with. Decoding the firewall tag, VIN, etc. should clear all of this up. Here’s some info you might pore over.