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Discussion Starter #1
This is my first post in this or any GTO forum.
I have owned a 1972 Lemans with the endura option for over 30 years. I had it in storage for the last 20, and I just took it out yesterday.

20 years is a lot of dust. We cleaned it inside and out and put it up on jackstands. It is in solid condition, but a lot of it is disassembled.

I have gone two directions with past cars. If a car had VIN value, I tended to stick to the numbers-matching restore route. If the car did not I tended to build for performance. I'm thinking that the "$41.00 nose job," as GM advertised the endura option on a LeMans is not a collectible VIN or worth any more than a GTO clone. Alternately, in 1972 the GTO itself was only a LeMans option.

I added a lot of nice parts to this car before putting it in storage, and a few that are questionable. The "nice" list would include a 12-bolt posi with 3.90 gears and a hurst his/hers shifter. The questionable would be the Pontiac 400 with TH400 that are under the hood. Engine/trans sounds good on paper, but I never saw it run before sticking it under the hood, and now they have sat for two decades.

Now that I feel the infection of the Pontiac bug beginning again, I am questioning the direction I should be going with this car. It left the factory with a GTO body, but crap running gear which is long gone. It now has GTO-like running gear.

Now:


Goal:
http://img.photobucket.com/albums/v329/biomechanical_clone/72.jpg

That's my introduction. I'm curious if this is the best forum for me to discuss this car or if there are better ones out there. I'm hoping to talk about options and products to see what other people's experiences have been.

Thanks for looking!
 

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Welcome to the herd!
This is by far the best GTO Forum anywhere!! There are great people on here, and a wealth of knowledge. A documented Endura nose Lemans has real value, maybe not GTO dollars. I like the 400/400 and 3.91, thats a fun combo, but not freeway friendly-gear. What is the 400, heads, year, compression?
 

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Discussion Starter #3
I got the engine/trans from a friend who pulled it out of a car that was intended as a 1/4 mile car. The owner of that car went to prison and his family scrapped his car while he was locked up. I know it is a 400 with 6X heads, but I never pulled a valve cover to see if the rocker bolts are screw-in or pressed in. It already had an Edelbrock dual-plane manifold on it when I got it. I haven't checked compression- it still needs a wiring harness and many other parts before it will run.

I had already been building another engine for this car when this engine fell into my lap. It is still in NYC and I have since moved to AZ. That short block has forged pistons, armasteel crank and a high-lift 068 cam. I had 96 heads and 7K3 heads for it and also a TH350 with a shift kit.

I will have that mess of parts put on a pallet and shipped to me if this current setup doesn't meet my expectations.
 

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Discussion Starter #4 (Edited)
I wanted to pose questions, so here goes:

1. Has anyone used Eibach springs? I'm not sure how much of a compromise it is in this car. I have them on my M3 and I need to go diagonally across speed bumps and I can feel the expansion joints in the roads. What is the impact on 1970-72 A-bodies?

2. My car has a vinyl top. I am tolerant of these, but I'm far from a fan. Is there any appeal to these at all? Were they intended to replicate a convertable look, or what? I can't think of any reason not to rip this off before painting it aside from having to deal with the rust underneath.
 

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welcome Dave, glad you caught the bug again, you will find a wealth of info on here in your endeavor. few questions before answers.

1.) 6x-4, -6, -8 heads they are all different sizes and will have different CR's
2.) What are your plans for use, daily driver, weekend cruise, strip? (to run pump gas you will need to get CR down to around 9.5:1)

love the his/hers and the chevy 12 and th400 should handle anything you can throw at it, like Jet said the gear may be a little much for the freeway, think the stage four can go down to a 3.55 gear which is a nice street/strip gear. found a nice 12 bolt myself but it has a 4.68 gear, corner to corner in a hurry but would not be streetable with my 455. may buy it and go down to the 3.55 myself. Why Eibach, do you intend on lowering it? Stock springs (i used Moog) will ride and handle fine, if you want a little stiffer get the ones for AC car or order chevelle BB springs, and throw the extra money at good bushings and good shocks. I would get that motor running while its in there and build the other, then you can use which you want and sell the other, there are always guys looking for running 400's on here and other pontiac sites. And i say leave it a Lemans, Nothing like a sleeper.
 

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Discussion Starter #6
Plans for use: I'm not going to beat it up on a track or abuse it running quarter miles, and I'm sure not going to build it into a show car. Moving without pushing it would be a change. It won't be going on highways for any distances based on the gas mileage I can expect alone. It might be something to get into when I want to hear a loud engine and feel the G-forces as it chirps through the gears.

A sleeper? That isn't possible. My M3 is de-badged and has 325 mirrors and bumpers- that's a sleeper. This car has the endura front and I promise it will be loud with headers through turbo mufflers and out the back with 1971 GTO tips. I hope the last engine owner cammed it when he put the intake on- if he didn't I will stick in a spare cam I have laying around. No one is going to assume it will be slow. I already have all the GTO emblems and it is really just a small moral dilemma because I went through a purist phase where I hated "clones."

The 6X-? heads: I didn't know what you meant, so I popped over to this website: 6x Head ID
I looked for the number on the vertical boss. There wasn't one.


The springs: I lowered all of my BMW's for the past ten years. When I see the Pontiac right now it looks like it is up in the air. The springs on it are of unknown origin and are much thicker in diameter than stock springs. I picked up a set of Eibachs on ebay and I have not yet put them on. A friend and I are working from the bottom up on the car right now, so the springs will likely be in the next days' work (Sunday or Monday.) I don't know what to expect from them and was hoping if someone hated them they would warn me off. The car itself has A/C, but I doubt that matters too much in reality despite their being firmer factory springs available for ac cars. I live in AZ, the A/C is a must.

The 12-bolt: my mechanic friend was telling me that these are incredibly rare and he was shocked to see it. What do they cost now? He acted like he walked into fort knox when he layed under the car.

Instg8ter, what's a stage four?

Another question: I have seen the poly body bushings advertised forever. The current body bushings are original. Are these a worthwhile investment in cash and labor? Should I expect insane vibration if I ignore this?

I'm also trying to decide what to do about surface rust on the frame rails. Apparently I decided to brush undercoat on the underbody and I ignored the frame rails 20 years ago. Frame-off or sandblasting seem a bit extreme.
 

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What is the origin of the 12 bolt? Is it a Pontiac or Chevy? If it's a Pontiac, then you hit the lottery, if it's Chevy its still an awesome rear, just more common.
I put all the poly bushings in my front end, but stock body mounts. I guess mine are in good shape still, car handles great and rides dead smooth. I personally have never felt body flex on the chassis. If needed I would just put stock body mounts in. I put Hotchkis 1" drop springs in and they feel great.
GTO or Lemans Sport, I like that mine is a Lemans Sport. An endura nose Lemans is too cool, and I would rather be asked why I didn't cloan it into a GTO rather than is that a cloan..:cheers
 

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hey Dave, if you got the tags go clone, sounds like your 90% there already, no prob with clones as long as they are advertised as such when sold.

Have buddies that do foxbodies and they swear by Eibachs. Can't beat poly bushings in the front end, a must if you want more aggressive handling. they also have some newer bushing materials that guys are raving about.

I am doing frame on myself and still have to lift and replace body bushings, am told it can be done two at a time as long as the bolts and pan nuts are not too rusted, as for the frame i sandblasted and painted in epoxy after spraying the areas i could not get with POR 15 rust inhibitor (if its just surface rust this will do the trick, just wire brush the scale, do not grind to bare metal). and as my car was Ziebarted shortly after purchase the sand just bounced off must of the bottom of body pan so i re-coated it (if it was good for 45 years why mess with it).

my 6x-4's have the stamp on right boss on both sides says GM-4, you can trace casting numbers, or some other members more knowledgeable than i may be able to shed some light . 4's are perfect for a 455 to get it to 9.5:1 so i think on the 400 you would want 6's or 8's to get the CR down

Am told that the 12 bolts have four stages of posi carriers each carries a different range of gears, stage four being the highest 3.55 - 4.68 i believe

my word is far from gospel as i am new to the engine game myself, just passing on the limited knowledge i have accumulated in my project



1966 Tempest pictures by instg8ter - Photobucket
 

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Discussion Starter #9
12-bolt: I have no clue where it came from originally. It was on a different 1972 lemans- the same car that supplied the thick springs. Those thick springs or the crappy shocks were responsible for two accidents with that car. It would hop off of bumps and leave the ground. I traded a Buick 455 stage I engine with transmission to get that car just for the rear. Life was different before the internet- lol. I searched A body 12-bolts on ebay and they are going for 2 grand- pretty impressive. I guess I need to see the numbers on it to see if it was built for Pontiac or not.

Springs: I had to look up foxbody. I'm shocked Ford talk isn't banned here- LoL. Eibach are great on BMW, too. I have never seen them on an A body and was hoping for personal experience. I searched on here and they only popped up on the Holden GTO's. 2004-.

Clone: I can't promise that my clone will be sold as such because I'd need to be dead for it to be sold. People have tried to buy this thing from me for over 20 years. The vin number is blatant because the engine code is for a 350, PHS will never see a dime spent on this car. Since I won't be going for a correct build, clone questions will be the least of my issues. The 1971 exhaust with the 1972 front fender scoops should be enough to confuse the slightly dangerous observer.

Heads: I guess I'll need to put in more effort to look at those bosses with some light and possibly mirrors just to know what I have. I have no intention of changing the heads without yanking the whole engine to put my fresh shortblock in.
 

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i believe i read in the restoration handbook that the corporate 12 bolts used in Pontiacs when they introduced the 455 were manufactured in canada if that helps.

get your head casting numbers and check them here, that should tell you CR

Pontiac V8 Casting Numbers
 

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Hey Dave,
You've got the makings of a really fun car there. If you've got budget room for it, you might consider a stroker kit for that 400. If those heads CC out to about 87 cc's, then with what you've got already, around $1400 plus the cost of some machine work on the block (bore it +.035) will net you a 461 that will make some serious torque.

Bear
 

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Discussion Starter #12
@Bear: I'll be happy to see it run for now. At the moment the budget is only the odds & ends to get it rolling and 100%. I have a reasonable sized collection of parts available.

Stroking the 400 isn't in the near future since I already have the previously described shortblock with 0 miles as a backup in the case that this one has internal issues.
 

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How do you tell if the rear end is chev or pontiac? My 71 Lemans sport with 400 2bbl I bought for parts has a 12 bolt in it. Where do I look for markings on it? Or if I take a pic can you guys tell me what it is?
 

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stamping should be on top side of drivers axle tube toward the back about 7-10" out from where it meets center housing, will probably have to grind over it to see them as they are just hand stamped on assembly line.
 

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Discussion Starter #15 (Edited)
I did some tracking down of Cylinder head and engine codes.
I also found a website that I like better than the one you referenced: Cylinder Heads

The 6X heads have a date code of D277, which is April 02, 1977.
That makes them 6X-8. 180hp, 7.6cr 101cc
The block casting # is YC 500557. 170hp, 7.6cr
The Quadrajet even has a 1977 part number.
I'm pretty disappointed.
 

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I did some tracking down of Cylinder head and engine codes.
I also found a website that I like better than the one you referenced: Cylinder Heads

The 6X heads have a date code of D277, which is April 02, 1977.
That makes them 6X-8. 180hp, 7.6cr 101cc
The block casting # is YC 500557. 170hp, 7.6cr
The Quadrajet even has a 1977 part number.
I'm pretty disappointed.
The only real negative there is the block. 500557 aren't as strong as earlier 400's and that can become an issue for serious HP builds (550+) although there are some that have "lived" at higher levels than that. It seems to be a hit or miss proposition. Other than that - those heads aren't necessarily "bad" - especially on a stroker. As displacement goes up, you need more chamber volume to manage compression. Plus, Pontiac heads are known to vary significantly from the "published" factory chamber volumes so the only way to know for sure is to pull them and cc them yourself.

Bear
 

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Ive used Eibach drag springs and lowering springs in my mustangs and wouldnt use any other brand if I did it again. Retained the stock ride comfort.
 

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Discussion Starter #20
This has been slow going, but some progress is being made.
I decided to start underneath and work my way up.

The exhaust is done, as is the parking brake. The rear eibachs are in, and it doesn't seem to drastically low. I'm still concerned that the headers may be too low when the fronts are in, but it look like it will be a "go," at least until it poses a problem.
 
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