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Discussion Starter · #1 · (Edited)
My ‘67 Jeep Gladiator has got a SBC 307 in it. As expected, this motor has terrible performance. Fortunately, I have access to a “mostly stock” 1980 C3 Corvette 350, which would give me roughly 165-190 hp and more torque. Which is a huge improvement given this engine is pretty much free. Although, I am very unfamiliar with Chevy motors, so I have no idea if I can just pull the 307 and drop the 350 in. The 307 has an adapter plate hooking it up to an AMC bell housing Th400.

TL;DR: Does a ~‘70 Chevy 307 and a ‘80 Chevy Corvette 350 motor have the same mounting locations/ tranny bolt patterns? Are they interchangeable?
 

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What info do you have to verify you have a 307 or the 80 motor is indeed a 350?
there’s at least a half dozen small blocks that look the same but range in displacement of 265 to 400.
 

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Discussion Starter · #5 · (Edited)
What info do you have to verify you have a 307 or the 80 motor is indeed a 350?
there’s at least a half dozen small blocks that look the same but range in displacement of 265 to 400.
Well I own the 307 and checked all the numbers on the block a while back. I was disappointed to find out it was a 307, but it was free so… Forgot what year it was, but the power output is so abysmal that I assume it’s 70-73. The corvette motor reads “GM 5.7LG” and “14010207” so I know for an absolute fact that it’s an 80-85 350.
 

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Discussion Starter · #7 ·
Mesmerized by the numbers game, eh!
You’ll likely find out the 350 isn’t any better.

Check this link.


I know, I know, but it is a lot easier to get power out of a 350. If I already have it, I may as well drop it in right? I know it runs with no issues and maybe I’ll spend a few bucks on some gaskets and rtv, but I’ll easily make upwards of 30hp depending on the 307 year. I’m planning to save the 307 for a smaller project like a mini truck or “economy rig.”
 

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The other issue is you can use the 307 crank and put in a 350 block and make a good 327. 3.25 (307) stroke x 4.00 (350) bore. Simple cam like summit 1106 grind, flat top pistons, 55hv oil pump, basic 2plane spreadbore intake, 600 to 650 electric choke 4bbl, HEI with vac advance, good one piece oil pan gasket. If you come across some 305HO heads 64 to 58 cc, 1.94 intakes. Will be peppy and decent economy. It won't be a 383 stroker monster, but fairly inexpensive and dependable.
 

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Assuming both engines are in the same condition, just the extra cubes alone will be good for at least 20% more torque, and make it at a lower RPM. Possibly more than that, because I suspect a Corvette engine would have had better heads and more compression than a sedan or a truck 350. That's because even in the dark ages of emission controls, Chevy was always trying to eek out the most power possible for the Corvette.
 

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80/81 Corvette engines really suck. My 81 with rebuild ( I didnt do it) stockish cam, holley intake, Custom 780 Holley X I built, and headers made 205 hp to the wheels with a standard trans. Your 307 is probably rated at 200 hp flywheel. If the 350 goes in do some changes first
 

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Discussion Starter · #11 · (Edited)
80/81 Corvette engines really suck. My 81 with rebuild ( I didnt do it) stockish cam, holley intake, Custom 780 Holley X I built, and headers made 205 hp to the wheels with a standard trans. Your 307 is probably rated at 200 hp flywheel. If the 350 goes in do some changes first
Mild cam, 400 heads (larger valves, plus already installed), qjet, Edlebrock intake and headers (I own). I know these motors suck, but it’s definitely better than the 307. Numbers say it’s a ‘72 307, so 130 hp at best. Mileage is gonna suck, but I can’t get any more broke.
 

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1980 Corvette engine specs:

ZAK: 350 CUBIC INCH, 190 HORSEPOWER, AUTOMATIC TRANSMISSION
ZAM: 350 CUBIC INCH, 190 HORSEPOWER, MANUAL TRANSMISSION
ZBC: 350 CUBIC INCH, 230 HORSEPOWER, AUTOMATIC TRANSMISSION
ZBD: 350 CUBIC INCH, 230 HORSEPOWER, UNCERTAIN USAGE

The above numbers are "NET" horsepower. A 1970 307 made 200 GROSS horsepower. HOWEVER, that was dropped to 130 hp in 1972 when they started publishing NET horsepower. Comparing apples to apples, we are really looking at 190-230 net hp for a Corvette 350 compared to 130 net hp for a 307. No contest.
 
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