97 grand prix engine swap

**biscuit** · 03-06-2011

I have a 97 3.8L grand prix, will an engine out of a 99 fit and is there anything that I need to get off of the 99 to make it work in my 97? Thanks ahead of time for any information

**Bio248** · 03-06-2011

same motor. the throttle body is different, but they are interchangeable.

**curtcamaro** · 03-12-2011

Hey biscuit I'm doing the exact same thing...only my 97 GPGT car is getting a 99 regal motor, also the same, but post any useful info that you come up with it when you do it. Otherwise I'll do the same when I do.

**biscuit** · 03-14-2011

You got it, I let you know any snags I have. I pulled the old engine out last night and like the post below states the only difference is the alternator bracket.

**BillBoost37** · 03-15-2011

The base motors are identical in all the 3800's 97+. Swap a few accessories/brackets, rear exhaust manifold and flex plate. Those are about he only things to consider.

Reason I say flex is the H/C/G bodies had a 258mm converter not the 245mm.

**biscuit** · 03-16-2011

I mounted the transmission on the 99 motor last night and everything bolted up fine. What do you mean by 258 mm and 245mm, will I have shifting problems?

**biscuit** · 03-20-2011

The only things that I switched over from the 99 motor to the 97 motor was the coil mount (because it is integrated into my top engine mount), alternator bracket (because my new engine didnt come with an alternator and they 97 wont fit on the 99 bracket), and the throttle body. I just finished last night and drove it about 10 minutes ago and it is running like a champ. Feel free to ask any questions and I will do my best to help out in anyway I can.

**curtcamaro** · 03-20-2011

I'm starting this week so I'll make sure to ask if I come across any problems

**Tea Time** · 03-28-2011

biscuit.....u do the swap into a 97 gt or gtp?

**indyal** · 03-13-2011

Make sure you have the alternator from the 99 97 mounts different

**biscuit** · 03-14-2011

I just ran out to my shop to look, and dang it you were right! What do you think was the only thing that did not come with the motor...... the alternator. It looks like I can switch the bracket over. Do you know if that is possible?

**BillBoost37** · 03-16-2011

Grabbed pics to explain it better. The flex on an H/C/G body car has a larger bolt pattern for a larger torque converter. The 04+ cars came with dual drilled flex plates to solve this issue. Meanwhile the pattern on a W body is 245mm and the pattern on these others is 258mm. All this means is the bolts won't line up if you mix them.

258mm flex with 245mm torque converter looks like this.

Here's when i pulled it apart and put the right flex on it. See where the bolts are, that's the spacing.

This customer didn't mention he was supplying an H/C/G motor and 245mm TC. I noted it.

Here is how it looks when it lines up.

**biscuit** · 03-16-2011

thanks for the info, very helpful

**curtcamaro** · 04-01-2011

THANK YOU, that was the little bit of information I was missing.

**Bio248** · 04-05-2011

how do you cross thread a lug nut?

**curtcamaro** · 04-06-2011

First off, Not sure, some idiot that WAS helping on my car, he has now been demoted to armor-all duty.

2ndly I'm stuck. Alternator checks out good at o reilly's but the battery light still comes on and drains my battery when running/or not within the time span of half an hour.... HELP?!

3rd
There is a hole in the bottom side of the rubber hose running from the air filter box to the throttle body? I'm guessing some kind of drain plug that I am missing for some reason...I don't see anything that could plug in there. Anyone know what it is that I'm talking about?

**BillBoost37** · 04-06-2011

Don't put amour all on your car... it's crap.

And if you ever need to know how to best get a part out/off etc. Just ask. PS pump gets hung from the hood strut, remove the diff to engine bracket and the backwards bolt is a straight shot.

If someone forgets his lug nut super duper security lock then pull the ps pump and lower it.. using one 12-14" extension under the rear exhaust manifold you can do the backwards bolt and take the motor out w/o ever taking off a tire. Right Swiggles?

LOL BTW security lugs don't deter thieves..they only stop the owner from getting wheels off.

**Tea Time** · 04-06-2011

is the battery any good Curt?

and the hole on the underside of ur air breather tube is supposed to be there and im pretty sure that style of airbox is exclusive to 97 (i think it may be some 98's as well) but there is a piece that goes in there....just a black plastic piece....im not even sure it has a function....i've got a 97 in my yard n as soon as i can get a pic of the piece, i'll post it for ya (just a pocket part from a junkyard).

**curtcamaro** · 04-08-2011

I had a short, MAF sensor was shorting, replaced it and all of a sudden everything was fine.
Stud replaced, car runs great drives great and shoots off line faster than my old Grand Prix ever did.
Thanks a bunch for all the help you all have been. One more grandprix owner/lover is now back on the road. Just in time to take my gf to her senior prom tomorrow night. See you all in CHarles CIty/Cedar Falls in May!