Olds 307 to 400 sbc

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lilbowtie

Comic Book Super Hero
Jan 7, 2006
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Eh.. Do what you want, its your car.

If the 400sbc is what ya got, then run it. My Pontiac GP has a 305sbc in it.. Im not running out to find a 400 T/A 6.6 or a SD455 for it.. lol

-Gonz


By all means it's his car and he can do as he dam well pleases with it. The point is that is a rare collector car and in demand. If you look at the NADA blue book on it it is $24,000.00(high retail) vs a Calais @ $3,500(high retail). For this reason and this reason only (money) I would keep it pure.
 
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565bbchevy

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Aug 8, 2011
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For the swap you will have to change frame mounts to work with the SBC clamshell mounts.
The battery and starter are on the driver's side for the 307 and both are on the passenger side for the SBC so you will need to buy or make new battery cables and possibly modify or extend the wiring for the starter.
No oil pan issues and you can run a 7 qt pan with kick outs like Moroso or Milidon with no frame or ground clearance issues (probably need a mini starter though)
Your 700R4 will require modification to your existing cross member or you can buy a new one.
You will probably want to upgrade the radiator also for the 400 and buy hoses for a gbody Monte.
You will need all of the accessories for a SBC nothing will transfer directly from the 307 to your 400
You can get a serpentine set up for your pulleys and it will put the AC compressor in a similar location as the 307 or you can run a stock v-belt set up but you will need the AC hoses and hardline for a gbody Monte since it is on the driver's side.
For my SBC for my Regal I already had aluminum v-belt pulleys from a donor car so I made brackets to mount the AC on the passenger side for a v-belt so I can use the factory 307 set up plus I don't like the compressor on the driver's side.

And lastly try to save anything you remove just in case.

20180603_183948-1_resized.jpg
 
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Nov 4, 2012
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By all means it's his car and he can do as he dam well pleases with it. The point is that is a rare collector car and in demand. If you look at the NADA blue book on it it is $24,000.00(high retail) vs a Calais @ $3,500(high retail). For this reason and this reason only (money) I would keep it pure.

I didn't realize the book value was so high on the H/Os.
 

Yav8

Master Mechanic
Aug 19, 2014
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Manitowoc wis.
Sure would be hard to make the power out of that 403-455 olds for the same amount of money as the 400SBC. And he has it so why not use it.
 

fleming442

Captain Tenneal
Dec 26, 2013
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Sure would be hard to make the power out of that 403-455 olds for the same amount of money as the 400SBC. And he has it so why not use it.
Because it's a limited edition car- very similar to the @$$ clowns that drop Ls motors in nice GNs.
 
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Oct 14, 2008
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Their value does seem to be quite high compared to even the 442's. I see the 83 with the grey interior especially since they are the lowest number and had the most powerful 5L HO till mid year. The 7.5" is the real downer on it but it wasn't available till 84. Yah, I hate what this guy is doing an especially stupid if he cuts up anything. Tuck the 307 in the corner of the garage along with the special 2004R and get a different drive shaft to cut for the worthless 700R4 along with an aftermarket cross member. You may want to keep all the factory exhaust if still there, it is no longer reproduced. The exhaust is where GM really sh*t the bed on all the V8 G bodies. They could have done dual exhaust with dual cats but that might cost 5 cents, add the extra cost to the consumer. Look Olds added shorty headers, a Y pipe and better cat vs the awful crossover, along with 1970 style ram air, it added 30 hp. The 5 spd manual would have also added fun as well. I get the Olds 307 like sbc 305 was not the greatest performance platform but Olds improved hp on the even weaker swirl port motor but it never made it into production. The extra 30 hp and 5 speed Hurst shifted would have made an awesome 85 H/O and very competitive for that year but it was not to be. As said, do as you wish, just do it smart.
 
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Gonzo1970

G-Body Guru
Sep 30, 2018
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By all means it's his car and he can do as he dam well pleases with it. The point is that is a rare collector car and in demand. If you look at the NADA blue book on it it is $24,000.00(high retail) vs a Calais @ $3,500(high retail). For this reason and this reason only (money) I would keep it pure.

Granted, altho I think $24k is high.. at least around here. I know of one locally, in mint condition (not a joke), he was trying to sell for $12k, and never could so he kept it. Still know where it is if I ever hit the lottery or finish and sell my bus or something.. Also watched one here sell for stupid cheap ($5k).

Point being, they can be valued at whatever nada, hagerty, or whoever decides them to be, but if you can't sell them for that, the "value" put on it by some 3rd party entity just doesn't matter.

VW Buses are another prime example of this. Look up the value of a 1970 Westfalia Campmobile... $52k? LOL You can get very nice ones, all day long, for way less than half that. (I use that example because I have a 1970 VW Westfalia Campmobile I have been re-doing).

If I owned a H/O, and was in his situation with the 307 gone t*ts up and a 400sbc just sitting there.. Sure, I would plop it in and use it. Doesn't mean over time, I couldn't get another 307 and keep the rest of the drivetrain to retain the ability to go back to stock.

-Gonz
 
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MrSony

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Nov 15, 2014
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Des Moines, Iowa
Sure would be hard to make the power out of that 403-455 olds for the same amount of money as the 400SBC. And he has it so why not use it.
For the same money, they wont have more power... But they win in torque.
 
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Gonzo1970

G-Body Guru
Sep 30, 2018
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Funny, the guy is trying that 84 H/O again.

77k miles. Looks like it rolled off the showroom floor. $13.5k

-Gonz
 
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