Olds 307 to 400 sbc

[vanrah]

Greetings Tony HO & all; I see that you have got at least a $ dimes worth of opinions. I should mention that I'm a FAN of SBC 400's as I've used up 2 &1/3 of them during the last 35 years. And I'm also informed enough to understand automotive trends? Please re consider your idea & keep your Olds all Olds & numbers matching! Ten years from now you will be glad you did. Sell the 400 Chevy, find a GOOD machine shop & rebuild your Old's. I'm not very well informed about Old's engines, but can't ya put a stroker kit in it keeping the original block? Buy some after market aluminum heads, put the original ones in the boxes & save them for the future? Tweak the carb & distributor, go flat top pistons to raise the compression put an modest after market cam in it. You will double the HP & torque, it will drive like never before and retain it's valve? Now your up to at least $.13 cents worth of opinions, Ole' Bob.

 

[Ribbedroof]

The thing about "book value" is that it is the value for a front-line-ready vehicle at a retail dealer operation.

Private party sales seldom reach that level, as it is assumed the dealer offers other benefits in the way of alleged inspections, financing, etc.

 

[olds307 and 403]

Unfortunately the Olds 307 is a small bore, windowed main block. That means the Procomp, Edelbrock or any aftermarket heads can't be used. They use 2.07/1.68" valves, not good on a 3.8" bore. The stock 5A can fit the 1.87/1.56 valves(1.7/1.5 stock) from the 350 and would need at least a cutter under the valves. The available 4" stroke crank is similar in weight to the stock flimsy crank, billet 5140 or 4340 material is way stronger and with better stiffness. Cutlassefi does packages with better LS aftermarket rods and does custom pistons with ultra modern 1mm/1mm/2mm ring packs. Around 375 cubic inches is possible from a 307. Cutlassefi using the 5140 4" stroker crank has made 400+ hp and 500+ ft/lbs with 9 to 1 compression, basic 350 iron heads, 2"/1.625" valves with just a bowl hog and a mild roller cam using a 350 block with a 4.100" bore. That would be my choice but with a girdle and Canton oil pan, the 307 could survive some abuse. It would look like a stock 307 but perform much better and keep it numbers matching.

 

[AlanB]

Hey,

I did a SBC swap on my 87 Cutlass 20 years ago and I’ll post what I know about the swap. I had the entire process documented in a post on oldspower.com but the old forum there is gone.

First I wanted to share my opinion.
1) It’s your car, do whatever you want, or whatever is right for you. The more I think about it though, I wouldn’t do the swap on a Hurst/Olds if it were my car because it think it will hurt the value.

2) I believe any collectible G-body needs the original OEM parts to maintain top value. It needs to look OEM under the hood. That means matching block, original E4MC carb, emissions components, A/C. Etc. i think even stock block cars with all the emissions ripped out with a Holley will take a hit on value. If I had a GN, turbo Buick, Hurst/Olds, maybe a clean 442, I’d save all OEM parts. My 87 Cutlass? Not so important, dime a dozen, not collectible in my opinion.

So, if you want to swap, I recommend removing the 307 with everything intact, ECM, harnesses, all emissions, A/C, condenser, mounts, everything. So you can put it back someday. Just my opinion.

Ok so for the swap. I used a 87 Monte Carlo donor car so I had everything. I am running a Chevy 355 with E4ME carb and ECM, with all emissions intact except for EGR.

You need to swap:
engine frame mounts. 2004R should be dual bolt pattern for Chevy or BOP but you need to check.
All engine accessories. Alternator and AC are on opposite sides usually. PS pump, pulleys, brackets.
AC-compressor is on opposite side. You would need a Chevy condensor and lines to do a clean swap. Might need the compressor too, not sure.
Body wiring harness on drivers side will work but I swapped to the Chevy harness so wire length and connectors were all there. ECM wiring harness will not. OEM carbs are different. I wouldn’t run the Olds carb and ECM on the Chevy for many reasons. If you’re going aftermarket carb and no emissions then save everything. Everything, so you can go back to OEM someday.
Exhaust headers/manifolds obviously. Save the Olds stuff including the little emissions bits.
Battery. Olds in driver’s side, Chevy is on passenger side. I swapped the battery location so that all the Chevy wiring could be used without mods. Fortunately most Cutlasses have dual battery trays thanks to the diesel experiment in the early 80s. Also swapped the charcoal canister to other side, including the vapor line to the fuel tank that runs under the engine along the crossmember.

 

[jetsetw31]

In my OPINION. I'd sell the Chevy and put in a big block Olds. I have no clue where these guys are getting the Idea that a 455 with a good cam and intake will be out powered by a non-race spec 400sbc. That 400 will have to "SPIN" (above 6500rpm ) to out power a BBO. (Always with the Olds bashing around here. SMH)
My ADVICE. Like the others said SAVE EVERYTHING IT'S A COLLECTOR CAR. The special 2004R trans will need a rebuild, but can handle the 400 easily. If you race it, it will need to be beefed up. Get a aftermarket crossmember if you switch to the 700r4.
I too have done this swap. The monte carlo is not the only Gbody with the wiring on the pass side. You all forgot Buick and every car the had a Buick V6. They used the same starter location, alternator wiring, I started with a 83 V6 Cutlass and swapped in a 350sbc and a 4 spd manual.
The only thing you can't use from a Buick powered Gbody is the fuel line. It's on the driver's side. You also have to buy new PS pump lines for a Monte carlo, the 307's lines are not the same.

 

[olds307 and 403]

The main reason I am against a BBO, is there are more failures than SBO due to big journal's and heavy parts. Plus welding is needed for the A/C bracket and the valve covers are very close to the HVAC box as well. Plus I prefer the SBO and the billet 4" crank evens the playing field a lot.

 

[lilbowtie]

It's been interesting hearing peoples thoughts as to what TonyHurstOlds should do with HIS car and the diversity of people we have here and their thoughts. Most of us agree it's his car to do as he pleases although there is that BUT. Tony - what ever you do enjoy it. Here is a pic of my favorite car from the no box race @summit Raceway Park

 

[fleming442]

Most importantly: I see no mention of kicking said brother's *ss for blowing up his sh*t!