# 1970 GTO engine



## Charlie DuBois (Oct 30, 2019)

New to the forum and am considering buying a 1970 GTO. This is the first time I have considered buying a classic and know very little on how to proceed. Doing a lot of research. This vehicle is on consignment at a Houston Classic car dealer.

Now to my questions:
This car has a 400 CID from a 1969 GTO engine that has been rebuilt and bored .030" oversized. Has 9,000 miles on the rebuild and 068 cam and 3.43 gears. I have found that the 400 CID is a bored out 389.
I have a friend with a restored El Camino with the same engine and he told me that there was a crack in his engine and had to replace it with a rebuilt engine. He also told me that a friend of his had the same engine in his GTO and discovered a crack in his after buying. Should I be concerned about this?
I also found that the owner of this GTO owned it for 29 years and repainted the body in 1992. I have looked at it in person and the paint looks very good and chrome is also very good considering age. Interior is original and looks almost new.This indicates that the owner took very good care of it. It is almost all original and plan on using it to cruise, running errands, etc. It will not remain in the garage until special occasions.

If anyone would like to get further information it is listed on Gateway Classic cars and stock number is #1469-HOU . If you look at it what would be your opinion of the listed price? I believe it is high and would not pay listing price.
Thanks


----------



## BLK69JUDGE (Jun 10, 2010)

https://www.gatewayclassiccars.com/HOU/1469/1970-Pontiac-GTO

turn down the volume .... you would think that they would use a video devise newer than a flip phone , to try and sell cars...

gotta see that one in person .... no needle on oil gauge ..


totally out of focus video


----------



## PontiacJim (Dec 29, 2012)

You want to get the PHS documents for the car if not already supplied The owner shoud have these to authenticate the car as built. This will tell you if the car is indeed a GTO and what options it left the factory with.

I don't understand what you are asking with regards to 389/400? A 389 bore .060" can become a 400CI engine, but the ad states 1969 400 out of a GTO. A quick check on the block will tell you. A 389 will only have 2 freeze plugs per side. 400CI has 3 freeze plugs. If the engine came out of a 1969 GTO, it will have the correct block code, matching heads, intake casting, Q-jet number, etc..

If original 4-speed, the transmission will have the car's last 8-digits of the VIN stamped on it.

Pontiac did not make a 3.43 rear-end gear ratio. Maybe 3.23? This was the standard ratio used with AC. Next up, 3.31, then 3.55. 3.23 axle ratio will be stamped WF for non-posi and XF for posi found on the axle tube.

Price in my opinion is a little too high because the original engine is gone. Maybe 28-30K in the real world if everything checks out.


----------



## Charlie DuBois (Oct 30, 2019)

Pontiac Jim-Thanks for the reply. Helps a lot since I am not familiar with engines or cars that have been rebuilt or modified. 
Only information I have is what the info. sheet they posted which says it has a 400 from a 1969 that has been bored .030 oversized. I will be going back Monday to do another look and use your information.

There is also a Tempest GTO Tribute with a 400 and the detail sheet says it has a 3.08 rear end. Would that be correct?
Also-does there seem to be a problem with the 400's having cracks in the block?


----------



## PontiacJim (Dec 29, 2012)

Charlie DuBois said:


> Pontiac Jim-Thanks for the reply. Helps a lot since I am not familiar with engines or cars that have been rebuilt or modified.
> Only information I have is what the info. sheet they posted which says it has a 400 from a 1969 that has been bored .030 oversized. I will be going back Monday to do another look and use your information.
> 
> There is also a Tempest GTO Tribute with a 400 and the detail sheet says it has a 3.08 rear end. Would that be correct?
> Also-does there seem to be a problem with the 400's having cracks in the block?



3.08's is a correct gear. It will be for an automatic - no good with a 4-speed. It is more of a highway gear. Good for cruising, but will lack a little performance as compared to a 3.55, but a 3.55 will be uncomfortable at 70 MPH highway speeds.

No issues with block cracking unless someone had water in the block and it froze in winter time. Other things that can lead to cracking is improper head bolt length or over oiled head bolts. The Pontiac engine uses a bolt hole that does not go into the water jacket like many - it is more like a pocket. So if the heads/blocks were milled a good amount, or the wrong headbolts (standard 400 vs the longer Ram Air bolts) were installed and torqued down before the length was checked, the bolt could be forced through bolt pocket in the block and crack it. The other is if someone put too much oil on the threads of a headbolt to ease installation and help to get a good torque reading, the excess oil between the bolt pocket and end of the bolt can heat up and expand as the engine gets hot and the pressure has to go somewhere, so it can crack a block. Always check the bolt hole pockets to make sure no "junk" has fallen down into them and cause excessive pressure when torquing the bolt and cracks it. You could have a thin wall in a cylinder which when overbored becomes thinner and can crack under stresses. Not common, but going more than .040" over, like .060", you may want to sonic check the block - but who does? LOL. I go with what my machinist suggests.

By themselves, the blocks don't just crack unless you go with crazy HP which can split a block. The other situation is the 1975 and up blocks. These are not good for HP use. To same weight/money as HP levels dropped pretty low, Pontiac cut weight by making key areas of the block thinner and weaker. These will crack/break and are said to be kept below a 400 HP build - I would not use one period.

Basically, you never know what condition any engine is unless you are the one who pulls it apart, has your machine shop go through it, and then you rebuild it. There are those who will say anything to sell a car, and as most of our cars are "as is" sales, you have no recourse. It is always "buyer beware." The best defense is to educate yourself on these cars and don't jump too soon without a solid base of knowledge. There are specific areas to check for rot/repairs that can be hidden to the unknowing and eager buyer and cost a lot of money to fix later. :thumbsup:


----------



## Charlie DuBois (Oct 30, 2019)

PontiacJim said:


> 3.08's is a correct gear. It will be for an automatic - no good with a 4-speed. It is more of a highway gear. Good for cruising, but will lack a little performance as compared to a 3.55, but a 3.55 will be uncomfortable at 70 MPH highway speeds.
> 
> No issues with block cracking unless someone had water in the block and it froze in winter time. Other things that can lead to cracking is improper head bolt length or over oiled head bolts. The Pontiac engine uses a bolt hole that does not go into the water jacket like many - it is more like a pocket. So if the heads/blocks were milled a good amount, or the wrong headbolts (standard 400 vs the longer Ram Air bolts) were installed and torqued down before the length was checked, the bolt could be forced through bolt pocket in the block and crack it. The other is if someone put too much oil on the threads of a headbolt to ease installation and help to get a good torque reading, the excess oil between the bolt pocket and end of the bolt can heat up and expand as the engine gets hot and the pressure has to go somewhere, so it can crack a block. Always check the bolt hole pockets to make sure no "junk" has fallen down into them and cause excessive pressure when torquing the bolt and cracks it. You could have a thin wall in a cylinder which when overbored becomes thinner and can crack under stresses. Not common, but going more than .040" over, like .060", you may want to sonic check the block - but who does? LOL. I go with what my machinist suggests.
> 
> ...


Thanks again for the valuable info.
Still doing research but you mentioned the 3.08 being for an auto transmission when the Tempest says it is a 4-speed manual. https://www.gatewayclassiccars.com/HOU/1545/1965-Pontiac-Tempest#desc. Opinion on price of the Tempest as stated on the data sheet?
Could be a typo such as the GTO says it has a 3.43?
To clear up a few things. Not interested in a large cubic inch but that seems to be the most prevalent. Looking for something that I can drive several times a week locally with a little highway driving. Revving engines, popping clutches, etc. is not something that I do.

As I said previously both friends had cracked blocks and I have no further information about them. The 2 cars I am looking at have 8,000-9000 miles after rebuild. With those miles should I take some comfort that cracked blocks would probably not be an issue?

As you said: The vehicles are sold "As Is" and there is no way to check an engine until after purchase. I do understand that there may be some costs when purchasing vehicles such as these but a solid engine and transmission is first on my list.


----------



## PontiacJim (Dec 29, 2012)

Charlie DuBois said:


> Thanks again for the valuable info.
> Still doing research but you mentioned the 3.08 being for an auto transmission when the Tempest says it is a 4-speed manual. https://www.gatewayclassiccars.com/HOU/1545/1965-Pontiac-Tempest#desc. Opinion on price of the Tempest as stated on the data sheet?
> Could be a typo such as the GTO says it has a 3.43?
> To clear up a few things. Not interested in a large cubic inch but that seems to be the most prevalent. Looking for something that I can drive several times a week locally with a little highway driving. Revving engines, popping clutches, etc. is not something that I do.
> ...




Don't take this the wrong way, but the questions you ask tell me you don't know much about these cars and have never driven one. I suggest you stop looking other than for reference and begin a regiment of purchasing some of the books I and others have listed and read them carefully in building an understanding of these cars and what you are looking at. https://www.gtoforum.com/f12/books-pontiac-reading-135697/

The car appears to have 111,433 miles, not the "original 11,433 undocumented" miles. Once the speedo hits 99,999, it then clicks back to 00000 and starts again - not like modern cars which keep recording those miles over 100,000.

Ad says it is a GTO clone. OK, then why does the data tag have the "5N" on it that is the 1965 GTO option code? Is someone trying to hook an unknowing buyer into buying a tampered with or stolen car? I wonder if the frame's VIN matches the car's VIN? 

The body series on the _Data Tag_ is "2" = Pontiac, "37" which is a Lemans, not a Tempest, "37" = 2-Dr HT.

*HOWEVER*, the _VIN Tag_ says "2"= Pontiac, "33" = Tempest, "27" = 2-Dr Sport Coupe (a post car). And, the rivets are round head when many I have seen are the rosette style. _This car IS NOT a post car_, so VIN Tag is from another car - thus *ILLEGAL*.

Interior? 217? That is the code for dark blue interior. 216 is for red interior.
Paint Code B-B is for the color Blue Charcoal.

Engine paint does not look like rebuilt 8,000 miles ago. It should not be in as poor condition as it is, so the term "rebuilt" would be in question as I have stated to you earlier in purchasing any car that has a "rebuilt" engine unless it was done by a reputable and know engine shop that rebuilds Pontiac engines and you can call them up to talk with them and verify their work. Otherwise, "rebuilt" means nothing. You don't know what year the engine is, what it came out of, or what went into it.

Car still has the single reservoir master cylinder indicating drum brakes. I would not want a car with a single reservoir master cylinder simply for safety's sake if one of the brake lines busts, and I want a disc brake conversion up front. Drum brakes don't stop like modern cars and if someone pulls an emergency stop in front of you, you can't match their stopping distance and you'll put your car into their rear bumper, or worse. Disc brakes up front at least give you a chance.

One of the photos shows the lower front fender/frame and if my eyes are not deceiving me, there is bondo built up on the right of the fender attachment bolt - it should be smooth, as in original steel brace.

Air shock fittings at the rear bumper cross member. This can indicate weak/sagging springs in need of replacement.

Look above the undercoated gas tank. Looks rough and rusty as does one of the underside shots of the trunk floor.

Up front, a photo shows a shot of the right front frame looking at the inner fender well. Looks like rust/holes on the fender well just above the frame.

Suspension looks all original and will be worn out at the mileage listed. Looks rusty on the radiator support.

Next photo shows the right side front frame and it looks either heavily caked with dirt & crud or a ton of under coating. Does not look good to me.

3.08 gears with a 4-speed is going to most likely burn up clutches. Put that car on a hill/incline and see how much you will have to slip the clutch to get moving. If th tires are anything taller than the factory 26" height, this will lower those 3.08's even more. Sure, you can do it, but expect the clutch to wear out faster than normal.

This car looks good & shiny, and that's how people get sucked in. First, I question the true identity of the car - tampered with, salvaged, cobbled together, stolen, or other. The PHS documents would give you more facts about the car.

The price is way out of line. You are looking at putting more money into it after purchase. It's a Tempest. I'd price it at 16-18K knowing I'll be dumping more money into it over time and not be surprised if rust starts to appear in places.

But, until I sorted out that Data Tag/VIN and knew the car was a legal, I would not touch it with a ten foot pole. This is the kind of knowledge you can arm yourself with when looking at any GTO, Lemans, Tempest. 

And, I would not buy a car from any "specialized" auto seller - and you have just seen why. They don't authenticate anything and could be selling illegal/stolen cars, they are simply middle men looking to turn a profit and their prices are typically out of line for what the car is. Buy from a private individual who is less likely to bend you over a barrel. But, maybe you are OK getting an overpriced bad deal. I personally can't afford to throw my money away 'cause i have so little of it to begin with. :thumbsup:


----------



## Charlie DuBois (Oct 30, 2019)

Thanks again for the valuable info. Yes, lot's to learn and I saw your post with the detail explanation of inconsistency.

You are correct that I know little of cars of this age.:smile3: Much more research and knowledge needed.


----------

