307 to 350 swap

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Old August 6th, 2020, 06:22 PM
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307 to 350 swap

I’m new to Oldsmobile. I just brought an 84 delta 88 with a 307 in it. I want to buy a crate 350 from autozone but it the diesel one they trying to sell. Is there another olds I can get a gasoline 350 out of to fit. And what is a good transmission to get to put behind it?
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Old August 6th, 2020, 06:44 PM
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Olds made gas 350s from 1968-80 and any of those are pretty much a drop-in. Found in 2 and 4 barrel versions in Cutlass/F85, Delta 88s and 70s Omegas. 68-75 are better; later ones have windowed main bearing webs. Use the accessory drives from the 307. You will probably want to run it off-computer but 350 can be adapted to the C3 system.

I would personally get the 200-4R trans built to take the 350. It has good gear spread and OD.
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Old August 6th, 2020, 06:47 PM
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Welcome aboard Dink,

1968-1980 Oldsmobiles are the years that may have 350s in them. 1968-1976 are considered the best years. Later years can also be found in other car brands.

Your gonna likely want a THM350 as the transmission to go with it, which shouldn't be too hard because that was the most common factory pairing.
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Old August 7th, 2020, 04:52 PM
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You can still find good running mid 70's Olds 350's. The 71 to 76 motors are good but have 8 to 1 compression with the same cam as your 307, only a modest improvement over your 307. Don't overlook a 403 if a good runner can be found, again 8 to 1 with the same cam but more torque. I agree, do a shift kit and remote cooler on the stock 2004R trans, also consider a rear gear swap as well.
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