[davetc]

i picked up a 70 chevelle with a 350 in it(not running). the owner still had the original engine, matching numbers. i am wondering, if the original is rebuildable, is it possible to put in a 350 crank? i am not interested in peak performance for this car, just fun. also thinking bout in the future putting a supercharger on it with lower numerical rear gears for cruising and fuel economy. is this just a dream? anyone have any ideas or thought about this idea? thanks

[strikingthematch]

Well if it has a 350 and it's not running it might be worth a look to tear it down because in my mind if you can use that then go for it a rebuild on a 350 is money better spent then on the 307 unless you want matching numbers. It would give you more power to start with and in any rebuild you bore it 30 over so you have a nice 355
Just what I have in my nice 71 Chevelle I also had a matching number 307 that im rebuilding at the time. I will stick to the 350 though.
For supercharging it I can tell you right now there is lots of things that go along with that you can either build the engine now to go with that or do it later. Get some good books on the subject

How to Build big inch small block by graham Hansen is a great book.

All in all if you want to charge it go with the 350

Take a good look at the 350 and see what is wrong with it.

If you want rebuild the 307...

[78 monte]

307s ain't that terrible of a motor(after you do the 30Kmi cam change lol) IMO.Its a 327 with a smaller bore.Its definetly a better motor than a 305.
If you want a matching numbers motor go for it.I would still have headers a carfuly matched cam and an intake on it though,myself.I thik they evan come with a halfway decent 1.94 head(993s).If you select the proper parts and rear gearing it should still be a fairly strong fun car,not like a built 350 but also not weak like a smogged out stock 305.

[davetc]

i am told that 350 got hot and that is why it died. so not too sure about that one. plus i kinda like the idea of matching numbers. i have checked in books on the journal size and they are close. i figure i can cut one or the other to fit. only thousands of an inch. so with the 350 crank it should be around 328 or 330. gonna try my hand at body work. this one is pretty clean. a few dings here and there. only one panel i am curious about, looks worked. oh well the technology now is amazing. it should be fun and interesting. thanks for the info.

[78 monte]

If your gonna exchange cranks put the 307 crank in the 350 block and make a large journal 327.
I wouldn't put the 350 crank in the 307 you prolly won't see that much advantage to it,as the 307 block has a smaller bore that will shroud bigger valves a bit.

[DoubleVision]

The rod and main bearing journal sizes between the two engines are the same. The 307 was created by using the 283`s 3.875 inch bore with the 327`s 3.250 inch stroke, it was made to be a small displacement low RPM high torque engine. to place the 350`s crank into the 307 would require custom pistons which will get expensive fast. it would need a 350`s compression distance of 1.560 but in a 307`s bore size. this would yield 328 cubic inches with a standard bore. all I`m thinking it would do with the right pieces is make it more of a torque engine which is fine for the street, but why do this when you can invest into the 350? it has more cubic inches, more power potential and will be cheaper on your wallet.
Cubic Inch Formula:
Bore X Bore X 0.7854 X Stroke X Number Of Cylinders =

[strikingthematch]

agreed

[ratlover]

I have a buddy with the same setup...call it a poor mans 327 4 bolt main. I believe you use the 350 pistons and rods but not sure. I will have to ask him. It goes like hell. He has a 72 chevelle with 4.11 gears, and I am not sure if I can beat him with my big block. Have not been able to line up a race yet.... will report back.