calli.uwu

n00b
Aug 4, 2021
3
1
I've got an '86 Cutlass Supreme with a junkyard 1987 307 (because I threw a rod in the og 307) and this engine isn't far from death. I'm thinking of doing a junkyard Vortec swap to it and I am not very knowledgeable with engine swaps this big. Anybody got any tips? Also, what kind of Vortec should I get and what transmission should I pair it with? Thanks.
 

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Wageslave

Royal Smart Person
Jan 25, 2017
1,470
113
A crate engine would be the way to go if you have the cash. That would gave you a known good engine with a good idea of output. Barring that, a junkyard pullout with reasonable mileage would be a decent option.

I would recommend keeping the CCC system and fit it over to the new engine as it will adjust itself to the additional displacement with ease. Either way, you will need a new SBC style HEI distributor from a similar year G-Body.

You will need SBC motor mounts that are bolted to the appropriate holes in the frame and SBC clamshells for the motor side. Car ones will sit the motor slightly lower but truck ones will work as well.

You can get a complete serpentine drive from a few places. An F-Body, a 2nd gen S-10 4.3, or a full size Chevy Truck 1988-98.

As far as transmissions go it depends. If you have overdrive in your car now, it is a 200-4R and you can likely bolt right to it. If you don't have overdrive, a TH350 with a Chevy bolt pattern should swap in easily. Check to see if you have a few extra bolt holes on your transmissions bellhousing that are not used. If you do, that means that it is multi-pattern and should accept BOP and Chevrolet bolt patterns.
 
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Streetbu

Know it all, that doesn't
Supporting Member
May 22, 2011
2,758
113
Central NY
They made both 305 and 350 Vortecs. Make sure it's a 350. You'll need frame mounts, you can get them from UMI.


You'll need an electric fuel pump since they don't have a provision for a mechanical.
 
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ELCAM

Greasemonkey
Jun 19, 2021
227
43
Some of this is mentioned above.

Olds to chevy

Need an engine with all accessory pulleys and brackets, Can use existing PS pump and alternator (use pulleys from donor engine). Or everything if it is serpentine belt.
Need dual pattern or chevy bellhousing/ transmission, chevy flywheel or flexplate.
Chevy motor mount brackets and clamshells
Vortec is FI only need aftermarket manifold, electric fuel pump
Chevy air cleaner or aftermarket w/PCV stuff
Battery tray moves to other side
Wiring modified, starter on other side, oil pressure sending unit on back of engine instead of front.
Heater water valve will need to be modified/ replaced.
Exhaust system.
Distributor.
Charcoal cannister to other side. Steel line from tank is now on wrong side

I am sure I forgot something.
 
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87National

G-Body Guru
Apr 15, 2009
518
63
eastern SD
I've got an '86 Cutlass Supreme with a junkyard 1987 307 (because I threw a rod in the og 307) and this engine isn't far from death. I'm thinking of doing a junkyard Vortec swap to it and I am not very knowledgeable with engine swaps this big. Anybody got any tips? Also, what kind of Vortec should I get and what transmission should I pair it with? Thanks.
There seems to be some confusion....are you referring to the 5.7l gen 1 motors found in 96-98 GM trucks? Or the gen 3 5.3l, 4.8l, 6.0l found in 99+ trucks?

GM uses the term "Vortec" to describe both.
I agree to rebuild the 307. If you put a 5.3L it will cost $10k easy. Nice car by the way.
You certainly can spend $10k......but you don't have to spend anywhere near that.
 
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MJScarangella

Amateur Mechanic
Sep 24, 2020
280
63
Pennsville, NJ
This isnt true.. I have a heads cam 5.3 running on a Holley and it no where near 10k..
Well, the reason my swap was complete within four months was because I opened the wallet.... YMMV
 
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