1987 Grand Prix Project

UPDATED 7/27/2012--Cleaned up some of the clutter in this post and updated with more current events in place. 😀

Hey everyone, I've been on the forums for several months now and decided I should finally layout my project plans for the '87. I've enjoyed this site a lot since I first joined and I'm glad to have found this place to hangout and gather information from. I'm no expert by any means and sure some, if not most, of you would gladly help me along with any questions or concerns I have. Most of what I have in mind I won't be able to do for a few months. So, I thought it would be a good idea if I got as much information from everyone as I could before diving in and finding out the hard way on what will and won't be good combinations for this build.

A little background on the car. It still has the 305 c.i. Chevy engine coupled to a TH2004r transmission and 2.41 final gear ratio. Everything is pretty much in stock configuration apart from the catalytic converter replaced with a cherry bomb exhaust from the previous owner. The engine and transmission were both rebuilt around 70,000 miles ago and I do have the paperwork from the previous owner of everything done to the car which is a big plus. The interior is in fairly good shape. The dash is all good with no cracks or anything. The 40/60 bench seat and possibly the back seats will need to be re-upholstered, especially the drivers seat which has a few holes. I have contemplated doing away with the bench seat and sticking in bucket seats, but I decided against it. I want to keep it as stock looking as I can on the inside, including keeping the column mounted shifter.

Anyway, on to my build ideas! :wink:

Drivetrain Updated

At first I was going to keep the little 305 engine and modify that, but decided to go with my 1969 Buick 350 from my LeSabre 400. Then an engine swap fell threw and I was back to the little 305 again.. But wait, then the engine swap became an option again and I'm back in business! Going to go big with a Pontiac 455 with a TH400. 8)

I previously bought the exhaust, thinking I would be going with the 305, but I think it will still work for the 455 engine..
http://www.summitracing.com/parts/FLO-817456/

Some kind of open air element air cleaner similar to this as an example.


I'm shooting for around 350-400hp+ and wherever torque may land with a big block. :lol: The Th400 should be able to handle the grunt from this engine, they were known to be bulletproof so to speak.

Interior

Not much to really change or add here. I just want to maybe re-upholster the seats, get a plastic cover over the seat belt strap holder that's bolted on close to the back quarter window, maybe new Body by Fischer rocker plates, and maybe new carpeting. I also need to replace the front 3.5 speakers and rear 4x10 speakers.. How much of a PITA is this and any quality speakers, or upgrades, that you guys recommend? I need to also re-attach the arm-rest handle to the door panel. I might need to go in and investigate since the screw isn't staying.









Exterior

Same with the interior, not a whole, whole lot to do here but still some work. I want to sand everything down and re-paint it with some performance red paint my friend has laying around and said I could have for free. Bonus for me since this will be a budget build, though we will see after I'm all done.. :lol: I'm also going to get a Pontiac hood RPM tach like this one to give it a little more Pontiac flair.



I also have the original trunk lid, but it's dented around the key lock hole. You can sorta see it in this picture. How hard would it be to get those dents out? Or would it be easier to replace it?



I'm also going to be sticking with the stock Pontiac Rally II wheels that are on the car, just strip them and repaint them.



That should about rap up everything I plan on doing with the car. Any thoughts and opinions would be much appreciated! I will also be updating this Opening Post with any update information that I do with the car. Thanks for reading and helping guys.

Thanks again guys. 8)

Bowiemontecarlo86 said:

Wow a UN cracked dash I would get a dash carpet for it. Sounds like a nice build you got planned. Why do you got to replace the body by Fisher door sills? Also I would junk that trunk lid and get another. Dents around the lock cylinder are hard to pound out. Nice project car tho bro can't wait to see progress pics.

Click to expand...

Thanks. 🙂 Ya I was pretty happy about an un-cracked dash, saves me time and money with a new one that's for sure. The Fisher door sills are starting too corrode on both sides so id like to get new ones, and probably a new carpet as well eventually. Ya, I couldn't see away to actually pound them out, so I'd probably have to replace it. Wish I wouldn't have too, it being the original and all, but I'll do what I have to do.

clean8485 said:

2 things that might be a concern. Is there any kind of smog check program where you live? Also, the 200R4 transmission thats in the car may not have the correct bellhousing bolt pattern to bolt to the Buick engine that you're proposing to put in the car.

Click to expand...

No, we don't have any kind of smog checking around my area. The The2004r is actually an universal transmission between the GM engines. So I shouldn't have to worry about that, but thanks for pointing it out. I know some people forget about this at times when choosing transmissions.

Blueboy84 said:

Good luck with the build! I like the hood tach idea...think that will look cool!

I've heard a mixed bag of stories on whether the 7.5 rear will hold up under that kind of power/torque. On a budget, you could leave it and keep your eyes open for a donor. If it's not a posi rear end, you'll have traction issues tho.

The Monte SS's had either a 7.5 3.42 (83-84) or a 7.625 3.73)... look for a 8.5 out of the GN or 442.

Keep the updates and pics coming!

Click to expand...

Thanks! I also like the hood tach idea, makes it unique and is a nod to the Grand Prix's heritage. Ya, I was thinking about that as well and forgot to mention that, my rear end is not a posi rear. So, I will probably have traction issues. I've been keeping my eyes open for any 8.5's but they get pricey, and being a budget build, I'm going to try and keep it as price friendly as I can. Thanks for the information too. I couldn't remember if the Monte SS's had the 8.5 or not. I'll definitely keep everyone informed for pics and updates as this moves along. 8)

jerry455 said:

When I had my '86 LE I replaced the 305 with a ZZ3 crate motor 350. It looked just like the 305 that used to be there. I painted the motor black to look like the original 305. I put in a 700R4 in place of the original 200R4. I bought a Monte SS axle with a 3.73 and a posi. When sold the car a couple years ago I had over 400 timeslips from Milan Dragway and I never had a problem with the axle although I ran on street tires. I used to get 20 mpg on the highway and 14-15 around town. My best time was a 13.39 @ 102.78 mph with a best 60' time of 1.88. Not bad for a daily driver. I used 1 5/8" headman headers and a 2 1/2" dual exhaust. I weighed the car and it was 3610 lbs with a full tank and pwoer everything. The Buick will make more torque. I would look into Art Carr for upgrade parts for the 200 r4. The 200r4 has a 2.74 1st gear vs 700r4 3.06 vs thm 400 2.48 but 200r4 has .67 od vs .7 for 700 vs 0 for thm400. Good luck on the car it sounds like it will be a fun and fast driver.

Click to expand...

Cool, thanks for all that! Sound's like you had a nice sleeper looking engine bay to me, and I like that idea. I also plan on riding on street tires, so hopefully I'll be ok with the rear end that's in there. Though, I will be making a bit more torque, Which I'm only guessing at. Ya, the gear ratios and the OD gearing made me choose the TH2004r over the others. Plus the fact that it will bolt up just fine to my Buck 350 and is a 4 speed versus the TH400 3 speed.

dogshit said:

The Summit cam you picked is about as old and generic as they come and its too mild for your goals. Despite being rated at 10.25-1 a 69 Buick 350 assuming its still stock had an honest 9.5-1. This is very good because it means you need and can take advantage of more cam and still work well on pump premium. If you find out you need pistons taperformance has an on the shelf 60 over that is made for 10-1 compression. You would also want to stress relieve your rods & balance and good rod bolts as well as oiling system mods if you go into the engine.

The headers you picked will not work as they are for a sbc not sbb. There are no headers currently being made for a small block Buick and a gbody. The best thing you can do is get an inexpensive die grinder and clean out any slag bumps sharp edges from the inside of your stock exhaust manifolds. Oh yea and as the stock class racers do, cone out the manifold exit to match a 2.5" pipe. This is the most important part of the exhaust system for flow not further down stream. After that the X that you have would be a great addition however Its a pain down the road if you need to work on the transmission. A simple H pipe will do almost as well as the X. After that the Muff you picked is fine for a budget build.

Your goals of 350HP & 400 TQ will be difficult without headers. Here is a link of a Buick 350 build done by a Buick oriented performance engine builder. They later tuned this pump gas daily driver capable motor for 365HP & 390TQ. Built motors you can actually build more torque out of a 350 chevy but at less street driving friendly higher rpm. http://www.automachperf.com/350 Street ported heads with bigger valves and a competition valve job would be required to hit your goals.

The 7.5/7.625 rear you have is workable especially if you are not running slicks or drag radials. But the 2.41 airplane gears will kill your acceleration and not help your overall mileage with an overdrive transmission. If you are taking advantage of your 200-4R and you should you will want 3.73s. The cheap easy foolproof route if you or your local salvage yards can find you one is to swap a whole rear drum to drum from a salvage yard MCSS. Bonus would be if they came with a posi and or a rear sway bar. You can do this yourself with simple tools and common sense its a direct swap. If you can't locate one buy the gears and have an experienced shop do it. At least for the complete novice. Do it yourselfers mess this one up a lot.

Your 200-4R at minimum would need a good shift kit such as the one http://www.ckperformance.com sells. Sometimes they run a special for $100. When you have the trans out you can take it to a local shop for install. This way you are not paying them for the simple labor of removing it from your car. Also the generic 200-4R you have may have its W.O.T. shift points too low for it to fully take advantage of your 350. I am not sure where its set for the 305. You need a tach to test it although I am sure someone here knows just ask.

You probably have the performance robbing 2 barrel intake. If so here is what you need. http://taperformance.com/proddetail.asp?prod=TA_1235
A much better cam kit could be selected from here http://taperformance.com/products.asp?cat=159 Although its not the only place to get a good cam for a Buick. There are a couple Buick performance vendors any of them will get you a better cam then Summit. Lunati would also be a good place to get a cam for it. http://www.lunatipower.com/ProductGroup ... 297&cid=81

http://www.V8Buick.com is a great place to find motor advice for you Buick and they even have a special section dedicated to putting a Buick motor in a gbody car.

There are three good threads on 350 Buick into gbody on this board. Here is one http://gbodyforum.com/viewtopic.php?f=13&t=31138

Click to expand...

Hm ok I'll look into all those suggestions, and good to hear all this now instead of later, which is why I chose to post this ahead of my project starting point. I'll take a look at that forum and see what I can find out. I was also looking at T/A performance and suppose I'll go with them. My 350 is also the "H.O." Buick 350 with the 4 barrel carb and rated at gross 280hp and 375 ft/lb's . I didn't know about the 9.5:1 vs 10.25:1 compression difference in this engine, nor did I know or think about the different shift pattern of the TH2004r.. I'll also have to think about different gearing then, though I wouldn't mind that much about not having rocket acceleration, it would be nice. Thanks much dog, have a lot to think about and re-evaluate.

rmbaker47 said:

I just posted my project to wake up the 305 in my 1983 Grand Prix - you might find it interesting as an alternative to changing motors.

Click to expand...

Thanks, I'll take a look at it once.