Sbo 307 to sbc 350

88cutclassic

Not-quite-so-new-guy
Sep 24, 2022
8
3
Victoria, BC, Canada
I had plans to repair the stock sbo 307 in my 88 cutlass classic so that I could keep the ecu and all it's functions.
However; after realizing the air pump system was hacked out by a PO and there's a bottom end knock accompanying the massive oil leak, I will go the sbc route instead.

I have access to a rebuilt sbc 350 for $200, buddy will install it too. It's much cheaper and my main goal is to keep this gbody on the road, not in my driveway. My cars get driven. I know it's sacrilegious to Olds guys to drop a chevy motor in there, I know.
Really wanted to save the sbo but I can't justify paying a shop $2-3,000+ to rebuild a 34 year old 140hp v8, I am a 25yo dude after all...
Should I even bother hanging onto the 307, or scrap it?

Questions for the swap;
-what's the best option to control torque lock-up for the 200r?
-how does the stock 7.5" diff handle a sbc/ best alternatives?
-will probably delete the a/c for the swap, will that be a b*tch to instal later on?

Any other tips and tricks would be appreciated.
 

565bbchevy

Geezer
Aug 8, 2011
9,265
113
Michigan
I did a 355 SBC swap in my 86' Regal and never intended to do any repair on the original oil burning 307 so I gave it away.
IMO there is no reason to remove the AC, there is no interference when installing a SBC (since they came factory) and reinstall would be a lot of work for no apparent reason.

There are a few options for doing the convertor lock up for the 200R4 I chose the B & M kit that bases it on MPH and is adjustable with a dash mounted controller and you don't have to drop the pan for the install and works great IMO. There are others that use pressure or vacuum switches that probably work well also.

7.5's can't hold up to some power if you don't use sticky tires but you will probably want a different gear so at that time you could upgrade to a 28 spline carrier and axles for some added strength or look for an 8.5 rear which is a direct bolt in other than you need to shorten your driveshaft.
Beyond that there are many aftermarket options for rearends.

I am a Big Block guy but went with the SBC in my Regal just to have a nice cruiser and couldn't be happier with it, I also made brackets to mount the AC compressor on the passenger side and used new components for the factory 307 set up to make it work other than the hoses that I made.
20220612_184924 (1).jpg
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88cutclassic

Not-quite-so-new-guy
Thread starter
Sep 24, 2022
8
3
Victoria, BC, Canada
I did a 355 SBC swap in my 86' Regal and never intended to do any repair on the original oil burning 307 so I gave it away.
IMO there is no reason to remove the AC, there is no interference when installing a SBC (since they came factory) and reinstall would be a lot of work for no apparent reason.

There are a few options for doing the convertor lock up for the 200R4 I chose the B & M kit that bases it on MPH and is adjustable with a dash mounted controller and you don't have to drop the pan for the install and works great IMO. There are others that use pressure or vacuum switches that probably work well also.

7.5's can't hold up to some power if you don't use sticky tires but you will probably want a different gear so at that time you could upgrade to a 28 spline carrier and axles for some added strength or look for an 8.5 rear which is a direct bolt in other than you need to shorten your driveshaft.
Beyond that there are many aftermarket options for rearends.

I am a Big Block guy but went with the SBC in my Regal just to have a nice cruiser and couldn't be happier with it, I also made brackets to mount the AC compressor on the passenger side and used new components for the factory 307 set up to make it work other than the hoses that I mad.
Thanks for the reply!

-sounds like I may as well install A/C at the time of the sbc swap. Did you reuse the 307 a/c compressor? And what factory parts did you use? I like the idea of keeping the A/C on the passenger side so I could potentially use the exisiting lines. Less work is better imo (as long as it looks decent)

-After making this post, I searched online for a few hours to see my best options for lock-up kits. I'm between the B & M kit you mentioned and Painless Performance 60110 Kit. Leaning towards the Painless kit because it comes with a 4th gear pressure switch, brake pedal switch, and vacuum switch; so it's got a few trans unlock features which make sense for daily driving and it's completely "automated" (I dont want any toggles in the cabin), can pretty much install it and forget about it.

-realized my 7.5 stock is one wheely peelys. I'll be looking for a Posi unit because smoke shows. Any recommendations?

Lastly; what exhaust headers are you using on your regal? There's a ton of options out there but I'd prefer some headers that need little to no modification to fit the gbody.

*UPDATE
I'm in the talks with a buddy who has a 350sbc rebuilt bottom end, used heads, valve covers, new valve springs, intake manifold, headers, HEI distributor, headers, and some other bits and pieces for $300. Should I hop on this? The used heads should be cleaned, resurfaced. I'd prefer a complete motor but can't see finding one for a comparable price.
 

565bbchevy

Geezer
Aug 8, 2011
9,265
113
Michigan
sounds like I may as well install A/C at the time of the sbc swap. Did you reuse the 307 a/c compressor?
I replaced everything with new parts for my factory 307 even the compressor but only because I mounted it on the passenger side, factory V-belt SBC mount the compressor to the driver's side but the serpentine belt set ups for SBC mount it to the passenger side like the 307.

what exhaust headers are you using on your regal?
I have some stainless steel Ebay headers that fit really well without any real interference issues but there are plenty of options for SBC depending on your budget.

I'm in the talks with a buddy who has a 350sbc rebuilt bottom end, used heads, valve covers, new valve springs, intake manifold, headers, HEI distributor, headers, and some other bits and pieces for $300.

The deal sounds good for what you are getting even if you don't end up using all of it.
For me I like to build my own so I know exactly what I have and can build it for what I want it to do.
 
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88cutclassic

Not-quite-so-new-guy
Thread starter
Sep 24, 2022
8
3
Victoria, BC, Canada
I replaced everything with new parts for my factory 307 even the compressor but only because I mounted it on the passenger side, factory V-belt SBC mount the compressor to the driver's side but the serpentine belt set ups for SBC mount it to the passenger side like the 307.


I have some stainless steel Ebay headers that fit really well without any real interference issues but there are plenty of options for SBC depending on your budget.



The deal sounds good for what you are getting even if you don't end up using all of it.
For me I like to build my own so I know exactly what I have and can build it for what I want it to do.
Thanks for the info. I will look into a serpentine kit for the 350 so I can keep the factory A/C, then have my crappy compressor rebuilt or replaced.
 

88cutclassic

Not-quite-so-new-guy
Thread starter
Sep 24, 2022
8
3
Victoria, BC, Canada
Thanks for the info. I will look into a serpentine kit for the 350 so I can keep the factory A/C, then have my crappy compressor rebuilt or replaced.
And do you know if I'd be able to retain my heater, a/c, and cruise controls without the ecm? I'd prefer to get rid of it and all the unnecessary wires since I'm ditching the CCC system. Will likely be using a holley 600 carb so there should be vacuum ports ready.

I'm feeling like this car is leaning towards muscle/cruiser compared to just a cruiser.
 

565bbchevy

Geezer
Aug 8, 2011
9,265
113
Michigan
Thanks for the info. I will look into a serpentine kit for the 350 so I can keep the factory A/C, then have my crappy compressor rebuilt or replaced.
I bought a brand new Four Seasons heavy duty compressor for mine about 5 years ago and it has been working great ever since,
 

565bbchevy

Geezer
Aug 8, 2011
9,265
113
Michigan
And do you know if I'd be able to retain my heater, a/c, and cruise controls without the ecm?
I don't have any factory computer stuff on my car the AC/heat harness is not part of the computer. I kept the wiring tucked away for the cruise control but the factory set up is pretty ugly plus I am running a Holley carb so I would have to fabricate something to work anyways.
 
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88cutclassic

Not-quite-so-new-guy
Thread starter
Sep 24, 2022
8
3
Victoria, BC, Canada
I don't have any factory computer stuff on my car the AC/heat harness is not part of the computer. I kept the wiring tucked away for the cruise control but the factory set up is pretty ugly plus I am running a Holley carb so I would have to fabricate something to work anyways.
Did you need to run the 3 groove water pump pulley to run the a/c, or just the 3 groove crank pulley?

I'm in the midst of creating a "shopping cart" of necessary parts for the swap and I'm stuck there. So far I have;
-Long neck waterpump
-3 groove crank pulley (lwp)
-105amp Altnerator 1or3 wire
-Saginaw PS Pump
-2.5kw mini starter
-Holley Street Demon 625cfm
-A-Team Mechanical fuel pump
-ICT Billet Driverside power steering and alternator bracket kit (so it will be easier to install factory AC)
Cart is sitting at $1,700 thus far, oh well.
I'm opting for chrome finish for mostly everything. Wanting to do a black motor with chrome accents to accompany the exterior colour/trim. 😁
Still need heads to accompany this 010 SBC block. Any suggestions for heads that are decent for performance but wont break the bank? Or a reasonable price stock head/cam combo
 

565bbchevy

Geezer
Aug 8, 2011
9,265
113
Michigan
Did you need to run the 3 groove water pump pulley to run the a/c, or just the 3 groove crank pulley?
I have a 3 groove crank pulley and 2 groove water pump.
I wanted aluminum heads for my 355 SBC and went with these set up for hydraulic roller and with the PBM/Erson valves,
 
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