80 grand prix sj vortec swap

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Grand prix 80

Not-quite-so-new-guy
Aug 9, 2018
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3
I got a 1980 grand prix that I bought I love G bodys. Engine was junk I knew that buying it. I bought a 98 gmc yukon 5.7 that I'm in progress of converting over to carburation I'm pretty close. I know I cant use the stock pontiac trans. But I thought I ask what others used I know where i can get a 200 4r and also a 700r4 trans 200 4r is good its free 700 good but cost a pretty penny. I'm literally a couple days away from dropping engine in the vehicle now. Just didn't know what others are using and what flywheel will I need to use with the transmission to work with the engine. I know outer diameters and teeth and pitch all play a role. I sure would appreciatw any help. Cant wait to have another g body driving. I've owed many but this will be first one I've ever swapped an newer vortec into one so the whole converting to carburation is new not to bad so far though al I got to get now is a distributor for it and to lash out pushrods install intake and drop it in and all the small things of course
 

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pontiacgp

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Mar 31, 2006
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I find it easier to install the transmission to the engine and then drop them in. What engine and transmission is in the car now? Have you looked at the bellhousing of the transmission cause if it's a 200 4r it should mount on a 5.7 block.
 

Grand prix 80

Not-quite-so-new-guy
Aug 9, 2018
26
13
3
No I'm pretty sure it's a thm250c
 

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Grand prix 80

Not-quite-so-new-guy
Aug 9, 2018
26
13
3
I got a 700r4 that I'm going to be using and putting in it. I'm told it's a pretty easy swap either I'll have to weld a plate to side of existing cross mount or I can buy a mount that I guess mounts to the existing cross memeber and the gives the new 700 somewhere to mount
 

565bbchevy

Geezer
Aug 8, 2011
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Michigan
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Grand prix 80

Not-quite-so-new-guy
Aug 9, 2018
26
13
3
If your current trans works you could use an adapter to fit it to the SBC until you get the money to swap the trans to an overdrive.
https://www.jegs.com/i/JEGS/555/601...wydebhVK27WnBi1CKArd4KGHCSX799VBoCZEIQAvD_BwE

555-60170.jpg
Naw the trans in it is junk and so was the 301 motor in it sucks cause all original and everything worked to but i picked the entire car up for really cheap and said I'm buying and doing the work couldn't pass it up I love the grand prix wish it would of been 4th gen body but it was to nice to pass up. And I got a 700r4 already and have put alot of time into this and cant wait to be in another one. My first and 2nd cars were an 80 monte and a 79 monte have had many regals and Montes and olds as well but something about this car said buy it lol
 

Grand prix 80

Not-quite-so-new-guy
Aug 9, 2018
26
13
3
Fought me tooth and nail but engine is bolted down headers on hell of a tight squeeze on driver side may have to run a short oil filter the s5 is to tall I think and wont allow me to tighten headers down all the way or a buddy said just tap the oil filter on the corner lol smash it down a lil... crossmember isnt installed mess with that maybe lil later install see how far I'm off with stock memeber if I can make it work or just but one off kegs for 120 and then I'd know the degrees it is supposed to be will be where it needs to be. Then all the lil stuff. I'm sure it will be awhile longer tell I get it running
 

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Grand prix 80

Not-quite-so-new-guy
Aug 9, 2018
26
13
3
So I got a question i plan on usingthe entire serpentine set up and was also going to use the newer alternator. Has anyone got the 2 wire to 4 pin terminal adapter and used or did the samething if so can you tell me what part you used I see there are many different apadter or conversion harness. Thanks in advanced and i appreciate will continue to update photos
 
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