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 '76 GP with factory ASC sunroof/moonroof?
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steveeoaktree
Tribal Scout

11 Posts

Posted - 19 Nov 2015 :  4:23:40 PM  Show Profile  Reply with Quote
Hey there fellas, new to this particular Poncho site, hoping for some fresh wisdom. I bought a '76 GP in the spring. When she arrived from the northeast, there was a hole in the roof. Come to find out, it came equipped with a factory 38 x 22 ASC metal sunroof. It's just a model J with the thin block 400/TH400 tranny. Needless to say, the interior was trashed, and there was a 1993 Caddy sunroof taped in the roof opening. (bad purchase, my own fault for trusting...lol) I refuse to let her get crushed though. I have all of the interior found and dyed except the right rear panel, and need seat tracks for the bucket seats. (found a set of horse collar seats and console from a SJ at the junkyard) Would y'all know where to dig up any parts? I also have access to a 1964 GP motor and 4 speed tranny as well as a XX 988 engine from a TA but didn't want to kill any more value. Any wisdom to share would be appreciated! Thanks!

62,814 miles, trannys solid, does have an intermittent stalling problem

Tub
Sitting Bull

172 Posts

Posted - 19 Nov 2015 :  6:29:02 PM  Show Profile  Reply with Quote
IF the engine is the original numbers matching engine, I'd pull and store it, in case you ever decide to sell the car. You may already know this, but you'll have to check for the partial VIN. which is on the front of the block, right beside the lower part of the timing cover, on the passenger side. The last 6 numbers will match the last 6 numbers of the VIN, of the vehicle it came in.

You mentioned a couple of other engines. So, I assume you want more power than the engine you have in the car now. IF the XX 988 engine is ready to run, I'd go with it. It should have 6x-4 heads on it, which means more compression. They make a good bit more power than the engines with the 6x-8 heads. While it's out, a small Voodoo cam and some .027 x 4.160 Cometic head gaskets will increase power some.

http://www.lunatipower.com/Product.aspx?id=1774

If it needs a rebuild, I'd either stroke it, or buy a crate engine instead. A long stroke engine will help push the heavy GP along, a lot quicker than a 400.(Which will make it more fun to drive ! ) But, it'll still look stock, to most casual observers.

http://www.jbp-pontiac.com/products/engines_assemblies/rotating_assemblies.html#461_467

http://lenwilliamsautomachine.com/455_Long_Block.html

http://lenwilliamsautomachine.com/455_Short_Block.html

http://www.sandovalperformance.com/#!product/prd12/2017678915/budget-series-shortblocks-starting-%40

I'd stay with the TH400. A 4-speed conversion, in a GP would be too much trouble,IMO. If you stay with a 400 engine, then a stall converter will help the low end acceleration. Probably need at least 2600rpm stall. More rear gear will also make a big difference in acceleration. Unless you'll be doing a lot of high speed cruising, some 3.42 gears might be good.

If you decide to go with a stroker, you'll need to have the TH400 rebuilt, using a 34 element intermediate sprag & drum assembly out of either an early TH400, or a 4L80E.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2051541.m570.l1313.TR0.TRC0.H0.X34+element+th400+sprag.TRS0&_nkw=34+element+th400+sprag&_sacat=6000

There are lots of options, for different performance levels. Just depends on what you want, for the type of driving you'll be doing. And, what I've mentioned is by no means the last word on it--just a few ideas, to give you some food for thought.

Edited by - Tub on 19 Nov 2015 7:18:16 PM
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steveeoaktree
Tribal Scout

11 Posts

Posted - 19 Nov 2015 :  8:24:02 PM  Show Profile  Reply with Quote
WOW! You know, I have been researching many things while restoring the interior pieces and this site came up on many of the results... now I understand why. Thanks for the great info. It's been over 20 years since I have had a project (son's finally grown up and moved out lol) so I am a bit rusty. I did consider the motor and tranny out of the 64 GP due to the nostalgia factor, not really looking for a race car though. Reliability along with some good ol' Pontiac torque will be fine with me... I had considered even going with the XX engine (it needs gone through) and using a stock valvetrain with the 068 cam so it would live with the crappier fuel we have these days... all foreign owned. My 400 runs fine and has low miles, but it's a thinwall block which was a concern along with the roll pins instead of the solid dowels to locate the mains (from what I have read) It's sluggish with all of the pollution crud on it (exhaust manifold, intake egr,etc) and randomly wants to stall. Have rebuilt the entire distributor top to bottom, replaced the fuel pump (smelled fuel in the oil when it arrived) plugs, wires, and rebuilt the carb, twice. (soaked it the second time in the carb solvent pail) Brass float as well, but still stalls after getting on it when its warm. I believe it's the brake booster pulling way too much vacuum...? Going to replace it regardless as it is like 40 years old... ha ha. I'll figger out this picture thing and upload some of the interior progress. Oh the TH400 shifts and pulls great (although it shifts way too soon) but does leak fluid, assuming out of the front seal. She's in storage now, so recovering the buckets, rebuilding the console and shifter, as well as settin up the engine stand in the bedroom for a wintertime rebuild should keep the progress rollin'!

Thanks again for your advice.

Stevee
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Phil
The Great White Buffalo

USA
7221 Posts

Posted - 20 Nov 2015 :  06:27:47 AM  Show Profile  Reply with Quote
Just check that your other 400 has the correct number/location of motor mount holes for your GP mounts. Also, the primary concern with your 76 400 is the thin main webbing. But here again, double-check to see if it is the original engine as it too may have been swapped out at some time.

What are your plans regarding the moonroof issue?

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Blued and Painted
Chief PONTIAC

USA
3409 Posts

Posted - 20 Nov 2015 :  11:21:23 AM  Show Profile  Reply with Quote
Keep in mind, this garage kept GP sold for 2500 with a like new interior and paint. If thinking it would be a cool car to drive, then have at it. If your thinking you will make a profit on the vehicle, Not happening.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 04 Dec 2015 10:08:25 AM
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Steve C.
Crazy Horse

1675 Posts

Posted - 20 Nov 2015 :  12:26:52 PM  Show Profile  Reply with Quote
The History of Golde Sunroof/American Sunroof Corporation (ASC)

http://automotivemileposts.com/aschistory.html
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steveeoaktree
Tribal Scout

11 Posts

Posted - 20 Nov 2015 :  4:29:31 PM  Show Profile  Reply with Quote
Naah didn't even consider profit or loss, just a fairly rare (514 for the 50th anniv) cool cruiser. Not to mention, I sure hate to see these things keep disappearing. I guess a lot of it has to do with being able to bring it back to daily driver condition... If I had nothing to fix or restore, then what fun would it be... lol

Thanks

PS The engine is a 557 and the num's match. I have heard that they're fine up to 400hp if ARP studs are used, but have no personal experience with that.
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Tub
Sitting Bull

172 Posts

Posted - 20 Nov 2015 :  7:05:21 PM  Show Profile  Reply with Quote
"...The engine is a 557 and the num's match. I have heard that they're fine up to 400hp if ARP studs are used..."

I would not spend a dime on a 557 block, although many have done so without any problems. And, since your engine is numbers matching, all the more reason to NOT mess with it.

My advice is to spend your money on a non 557 block. The '71 thru early '75 481988 blocks are some of the most popular for hi-performance apps. The XX block is just as good, if you can use the 3-bolt motor mounts, or 2-bolt adapters.
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steveeoaktree
Tribal Scout

11 Posts

Posted - 21 Nov 2015 :  5:42:44 PM  Show Profile  Reply with Quote
Thanks to y'all for all the advice. I think that I'm going to buy the XX engine and keep the 557 to put back in if I decide to ever get rid of her.
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steveeoaktree
Tribal Scout

11 Posts

Posted - 21 Nov 2015 :  5:45:05 PM  Show Profile  Reply with Quote
Oh and I think that I may have the stalling issue figured out: Gonna pick up a new fuel tank from Ames and attach my filler neck to it, and run new fuel ines, new gauge + sock, etc... Found a crapload of rust in the tank, and the sock is blanketed with it as well.
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Phil
The Great White Buffalo

USA
7221 Posts

Posted - 21 Nov 2015 :  9:52:21 PM  Show Profile  Reply with Quote
Good luck and keep us up to date on the progress.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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steveeoaktree
Tribal Scout

11 Posts

Posted - 24 Nov 2015 :  10:47:08 AM  Show Profile  Reply with Quote
Will do. I am looking for 2 sets of bucket seat tracks to refurb as well if anyone hears of any. The ones on Ames show for up to a '72 and I am not sure if they'll work or not. I found a set at the junkyard, but I pulled them out of a '77 Camaro and they're shorter and one has offset mounting holes... (oops) Waiting to take the seat frames and rally II's to the blaster until I find a set.

Thanks again y'all
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steveeoaktree
Tribal Scout

11 Posts

Posted - 24 Nov 2015 :  7:37:31 PM  Show Profile  Reply with Quote
Well fellas, I went treasure hunting at Tecumseh junkyard today... ha ha and found an exact match to my "horse collar" buckets in a '68 LeMans with 1 1/2 good seat tracks intact. Also found 2 matching rear interior side lower panels, as well as the tranny linkage bracket for the console swap. Of course I then stumbled upon a '75 SJ 30 feet from where I was stripping the other SJ, and this one is in exc shape as well... so more goodies await me Friday. The owner showed me a 1965 421 in a Cat Wagon with the (then) all-new Turbo-Hydramatic tranny for 300 bucks... hmm 200 without the tranny. I believe the up bolt starters started in '65 so I'm considering using that and just doing a basic overhaul (and just use lead additive) It's been there since '77 and hasn't been apart like the 400xx engine (many hands have been in that). I dunno, decisions decisions lol.
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Tub
Sitting Bull

172 Posts

Posted - 24 Nov 2015 :  9:23:27 PM  Show Profile  Reply with Quote
"... I dunno, decisions decisions..."



The later model engines have LOTS of advantages, over a 421. IMO

The bare block is the only part of a 421 I'd wanna use.

But, I reckin you could use later model heads and pistons and make a 428 out of it.

Edited by - Tub on 24 Nov 2015 9:29:52 PM
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steveeoaktree
Tribal Scout

11 Posts

Posted - 26 Nov 2015 :  10:44:06 PM  Show Profile  Reply with Quote
Yeah, I had considered using the 6x heads off the 400 that's in it now... I do have an affinity for the older 421's and since the late 60's GP's came with 428's .. Truthfully even though sooooo many people have warned me about the '76 400's I have also had MANY people build them to decent 350 - 400 hp cruisers without issue as long as the roll pins are swapped out to solid dowels to keep the mains from wandering. Torque is all I want anyways as this will only be a cruiser...?? They're pulling the 421 for methis Saturday, who knows may just keep it around to save. I have picked up a second set of horse collar buckets and will probably just restore all 4 as I'm sure someone will need them eventually. I also picked up a second console base just in case. The shifter needs attention but can be made fine. I can't help myself as I dislike seeing these old Pontiac parts just rot away.
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steveeoaktree
Tribal Scout

11 Posts

Posted - 29 Nov 2015 :  3:08:41 PM  Show Profile  Reply with Quote
Sorry fellas, I have tried and tried to upload photos to imageshack... to no avail. Keeps telling me that I can only upload jpg,gif,etc... (although I only have jpg) as soon as it's working will give some photo updates!
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Latech
Cochise

USA
397 Posts

Posted - 29 Nov 2015 :  8:05:19 PM  Show Profile  Reply with Quote
This here is right up your alley

http://williamsport.craigslist.org/cto/5328460446.html

Its about 50 miles from me here in Pa.I was going to go look at it, but I don't have the time/money for another.
I have a TH 400 for this car also

Edited by - Latech on 29 Nov 2015 8:07:47 PM
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steveeoaktree
Tribal Scout

11 Posts

Posted - 30 Nov 2015 :  1:36:16 PM  Show Profile  Reply with Quote
You're the man Latech! Yessiree it is what I need. I am curious what engine is in it as they did have the 301 starting in either '76 or '77. Being an SJ it should be at least a 350. I know that in the earlier 70's the SJ came standard with the 455 though.
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Tub
Sitting Bull

172 Posts

Posted - 30 Nov 2015 :  4:06:17 PM  Show Profile  Reply with Quote
From the ad, you can't tell if the engine or the trans is a 400. I'd guess that the engine & trans are both 400's. But, you never know what could have been swapped in it, through all these years.

If it's the original 400, it'll be a 557 block.

But, the only way to know for sure is to look at the block casting number for yourself, or have a pic taken of it.

This article says that in '76 the Model J came std with a 350 2-barrel, but the SJ came std with a 400 4-barrel.

http://www.hotrod.com/features/history/stories/hppp-0607-1973-pontiac-grand-prix/

Edited by - Tub on 30 Nov 2015 4:20:50 PM
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Latech
Cochise

USA
397 Posts

Posted - 05 Dec 2015 :  5:54:57 PM  Show Profile  Reply with Quote
I just got an E mail back from the seller.It has a 400 engine.
could be a 350 or 400 trans.I am betting a 400
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cortcomp
Coyote

USA
5338 Posts

Posted - 06 Dec 2015 :  10:49:23 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I'd bet a 400 in a big car also.
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steveeoaktree
Tribal Scout

11 Posts

Posted - 14 Dec 2015 :  6:09:01 PM  Show Profile  Reply with Quote
Too bad it wasn't a 455 -- I did make it around to flushing the fuel lines, replacing all of the canister lines and filter, vacuum lines, and also pulled #1 to TDC and re timed the distributor. I had it retarded 1 tooth and it made adjusting timing tougher. Pumped all the old fuel out of the tank and replaced it with new fuel. I adjusted the carb as best as I could ( I had previously soaked it in solvent and rebuilt it twice as well as installed a brass float) She sure runs better. Did a fresh oil and filter change as well, and added a bottle of zddp enriched additive. No more fuel smell in the oil! ( The first thing that I did when I bought it was replacing the fuel pump and lines as I know what the alcohol does to them...) I also found a great machine shop today locally that will do all the machine work for either my 389 or 421 for a grand. It includes all of the block work, line boring,cam bearings, freeze plugs, pipe plugs into the gallery holes, and do the heads as well including a 3 angle valve job. I want to do the porting myself so he said that he'd throw in new valve guides and seals instead. Now just waiting until after the holidays for the body shop appointment to get the doors and hinges done as well as the new weatherseal kit installation including new inner and outer sweeps... Time to get to making some money I reckon!
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