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Old 02-22-2015, 09:42 AM
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Default Difficulty of swapping Pontiac into a chevy powered GA?

A 78 or 79 Grand Am just went up for sale in my area, (south Alabama).

I'm a novice concerning the 78-80 GA's, but I'm sure that it's not a 1980 from looking at the grill, and I guess that it was a california car since it has the 305 chevy.

The chevy mill is the only thing that has kept me from buying it at this point.
So how difficult would it be to swap a traditional Pontiac motor into it? What parts would have to be sourced and changed? Fuel lines, wiring, motor mounts, front springs? what about the radiator? Transmission I assume?

The car is decent shape as far as rust, worn original black paint with gold bottom, tan interior with console auto, seats ripped, gold snowflake wheels.

I seem to recall seeing an H in the vin. Does this signify the 305?

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Old 02-22-2015, 10:02 AM
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The 301 was the std engine in '78 and optional in the '79 & '80. So some G-body 301 engine and frame mounts should install any '70 up Pontiac engine. The correct holes should be in the frame for the Pontiac mounts. I think the Lemans and Grand Prix bodies were on the same frame as the GA. Of course, I could be wrong--wouldn't be the 1st time.

The fuel pump and starter are on the opposite side. You can buy or make an adapter to mate the Chevy trans to a Pontiac block.

http://en.wikipedia.org/wiki/Pontiac_Grand_Am

Here's a G-body forum. Don't know if it would help or not.

https://gbodyforum.com/forums/general-discussion.3/


Last edited by ponyakr; 02-22-2015 at 10:29 AM.
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Old 02-22-2015, 10:29 AM
KO KO is offline
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231 V-6 was the standard engine in Grand Ams, my father ordered one new in 79 and picked it up at the plant in MI and drove it home. Optional engines were 301 2bbl, 301 4bbl and 305 4 bbl. 305 was mandatory in California. I believe and I say believe because I have never actually done it but the frame mounts are the same but are in a different location on the frame. You will need the metal brackets that bolt to the engine (70 and newer Pontiac only). I have done this in a 3rd gen Firebird and just moved the mounts on the frame and used G body Pontiac mounts on the engine. The distance from the mount position and the the rear of the engine from Chevy to Pontiac is different by about an inch.

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Old 02-22-2015, 11:34 AM
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Default '78-'80 Grand Am

The '78 and '79 grills looked very similar. The '80 grill was different.
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Old 02-22-2015, 12:03 PM
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I don't know for sure, but here is a second article I found that says the '78 GA came std with a 301 2-barrel engine(except in CA). Then, the '79 & '80 GA came std with the V6.

http://www.hotrod.com/cars/featured/...tiac-grand-am/

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Old 02-22-2015, 07:50 PM
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Well I was referring from actual first hand experience with the 79 and his car is an 80

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Old 02-22-2015, 08:02 PM
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I will be watching this also as I am starting the build of a 455 for my 1986 Grand Prix 2+2 that also has a H code 305.

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Old 02-22-2015, 10:56 PM
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You'll need a set of these to start with. http://forums.maxperformanceinc.com/...d.php?t=769745

As you mrationed, the bolt pattern on the trans is different. Other than that, it should just be a matter of moving some wiring and fuel lines around. There enough guys that do this swap in reverse, Chevy into a Pontiac, that it can't be that difficult!

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Old 02-23-2015, 07:10 PM
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I have the mounts. I bought a turbo 400. I am hoping to have the engine ready to install this summer and hopefully drive. The brackets for the accessory drive will be the next challenge.

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Old 02-24-2015, 10:37 PM
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Quote:
Originally Posted by Singleton;
The car is decent shape as far as rust, worn original black paint with gold bottom, tan interior with console auto, seats ripped, gold snowflake wheels.

I seem to recall seeing an H in the vin. Does this signify the 305?
H signifies a 305 4bbl. That's better than a 305 2bbl, which I believe was the standard high altitude GA engine. There were probably a significant number more U code 305 GAs produced than H codes.
The Gold lower body color definately identifies 78-79 GAs. For 1980 they all came with Ontario Grey lower body, unless deleted to the solid primary color.

Post a link to the pictures if you can.

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Old 03-04-2015, 03:42 AM
rexs73gto rexs73gto is offline
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If you want the easiest way to wire the car all you need to do is order the engine front wire harness for a G/A with the 301. You can get the harness from American auto wire & that way all you have to do is plug it into the fuse block & wire it the correct way to the Pontiac engine. All the wires will be in the correct location for the Pontiac engine. I did this on a full size Bonnievelle when I swapped a chevy engine to a Pontic engine in it. It make the wiring swap much easier. Then all you need is to move the motor mounts, frame mounts. The holes are already there for the swap. Pontiac drilled all the holes in the frame just in case they were to use a Pontiac engine in the cars.

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Old 03-08-2015, 09:49 PM
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There is a 79 in Birmingham with a 301 for $1200. This may be an easier route.
If I ever found one with a 305, I would personally do a B1G Block swap and then head to the Chevy Nationals...........Not many Pontiac G Bodies came with a Chevrolet motor..

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Old 03-21-2015, 07:19 PM
jerry455 jerry455 is offline
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It seems like every Grand Prix after 1981 had a small block. Around here everyone seems to run a Chevy motor, especially an LS that is why I am putting Pontiac 455 engine in my 1986 2+2. I have always loved Pontiac motors and can't wait to get mine rebuilt and installed in my car. I am hoping to have a 12 second street car.

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Old 03-22-2015, 03:15 AM
rexs73gto rexs73gto is offline
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Most all G-body Grand Prix's came with the chevy 305 because that was the drop in engine for those cars. You could only get the 301 in those cars up to 81, so you either got a chevy 305 or the buick 3.8. But I'm with you install a Pontiac engine in your Pontiac.

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Old 03-27-2015, 05:42 PM
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You're probably passing up buicks in wrecking yards with the correct motor mounts in them. I worked in a buick dealership in 1982-85 and a bunch of the G body buicks came with 301s in them from 78-81. Regals had 301s or 231s in them almost exclusively.

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Old 03-28-2015, 09:18 AM
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The Buicks did have the 301 in them. One of the sets of block mounts that I picked up was from a '79 Regal.

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'80 Grand Lemans
Was 301 C.I. Will be bigger soon.

00 GTP NBM / Graphite, Stock
Sold Aug. 2011

70 GTO Black / Black TH400
460 CID, 542 FWHP, 580 FWTQ
(Sold, Fall '09)

04 GTO Black / Black M6
Back to bone stock and sold, fall '05.
  #17  
Old 03-28-2015, 08:03 PM
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I've seen a 78 Buick with a 301 in it. Surprisingly, it also had an aluminum radiator support.
The Grand Prix, 78-80 anyway, usually had the 301.
305 in Cali and high altitude...Colorado and parts of Canada.

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Old 04-04-2015, 02:14 PM
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Quote:
Originally Posted by iowapub View Post
I've seen a 78 Buick with a 301 in it. Surprisingly, it also had an aluminum radiator support.
The Grand Prix, 78-80 anyway, usually had the 301.
305 in Cali and high altitude...Colorado and parts of Canada.
I have also seen '80 Buick Centurys with the 265. they actually have 4.3 litre emblems on the front fenders. Brackets from these will work as well.

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Old 04-04-2015, 02:17 PM
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Quote:
Originally Posted by ponyakr View Post
The 301 was the std engine in '78 and optional in the '79 & '80. So some G-body 301 engine and frame mounts should install any '70 up Pontiac engine. The correct holes should be in the frame for the Pontiac mounts. I think the Lemans and Grand Prix bodies were on the same frame as the GA. Of course, I could be wrong--wouldn't be the 1st time.

The fuel pump and starter are on the opposite side. You can buy or make an adapter to mate the Chevy trans to a Pontiac block.

http://en.wikipedia.org/wiki/Pontiac_Grand_Am

Here's a G-body forum. Don't know if it would help or not.

https://gbodyforum.com/forums/general-discussion.3/
This car should have the TH200. I would replace it with a TH350.

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Old 04-08-2015, 05:20 PM
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Quote:
Originally Posted by rexs73gto View Post
Most all G-body Grand Prix's came with the chevy 305 because that was the drop in engine for those cars. You could only get the 301 in those cars up to 81, so you either got a chevy 305 or the buick 3.8. But I'm with you install a Pontiac engine in your Pontiac.
There was also the buick 4.1,4bbl, V6 .i didnt know there was a 4.1 till my current 82 GP.shes getting a 455 swap in a couple weeks.

You exhuast choices are limited,stock log manifolds or ram air manifolds.if you got the money to spend there is only one place i found that makes headers for g bodies with pontiac motors, http://maddogheaders.net/

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