# Did GTO Use Different Cams For Carter 4 Barrel & Tri Power 389 Factory Production Gto



## take5 (Aug 9, 2009)

*Did GTO Use Different Cams For Carter 4 Barrel & Tri Power 389 Factory Production Gto*

Are the cams in a carter 4 barrel and tri power 389 the same?
Were there any options with cam availability for the 389 engine when originally produced?


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## Rukee (Feb 8, 2007)

The Tri-power engines got the 068 cam, which is different from the 4bbl cam.
I believe it was like a $215.00 option, you got the intake manifold, the three carbs and air cleaners, and 068 cam.
Wish I could buy a truck load of them now for that money!!


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## geeteeohguy (Feb 2, 2008)

The tri-power got the 068 cam as Rukee stated. The 4 barrel cars got a milder 067 cam, and there was an 066 cam in milder 2bbl engines. These are the last three digits on the factory camshafts. For specs and actual part numbers, you'll need to crack the books or do some surfing. I don't have that information in my head any longer, if I ever did. There are "better" cams to run these days with our poor quality fuel and modified compression ratios. A lot of the computer designed high-tech cams are VERY similar to the ancient, MacKellar-designed 067,068,744 cams of the '60's. The Jim Hand articles are excellent for information on this sort of thing....


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## geeteeohguy (Feb 2, 2008)

Just looked it up: Tri-Power was a whopping $116 option in addition to ehe option package price. The ENTIRE GTO Option package cost $296 more than the price of a LeMans. Doesn't sound like much $$$ today, but when these cars cost $3,000 new, $296 was a big chunk. Still.....why WOULDN'T you get the GTO?? (these are '65 prices). Also strange how a $116 option on a car 45 years ago can bring a 30% premium in pricing compaired to a born-with 4bbl car in today's world, with all else being the same.


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## Rukee (Feb 8, 2007)

whoops, missed it by 100 bucks.


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## take5 (Aug 9, 2009)

Thanks Rukee & GTO Guy.
I will be doing some more research and would like ALL thoughts and input regarding the following.
I am restoring my '66 GTO and it has the Carter 4 barrel. The 389 engine has 121000 miles, doesn't burn any oil, has good compression but the rear main seal will be replaced. I am not planning on pulling the heads, but will be replacing the timing chain. Also, thinking about placing a different cam in the power plant. Nothing too radical in cam modification and want to hear about ALL YOUR IDEAS REGARDING CAM MODIFICATION FOR A 1966 GTO THAT WILL RETAIN A HEALTHY SOUND & PERFORMANCE, BUT NOTHING LETS SAY EXTREME.


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## Rukee (Feb 8, 2007)

I wouldn't put a big cam in there with that many miles without freshening up the rest of it.


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## johnnylightning03 (Nov 27, 2007)

take5 said:


> Thanks Rukee & GTO Guy.
> I will be doing some more research and would like ALL thoughts and input regarding the following.
> I am restoring my '66 GTO and it has the Carter 4 barrel. The 389 engine has 121000 miles, doesn't burn any oil, has good compression but the rear main seal will be replaced. I am not planning on pulling the heads, but will be replacing the timing chain. Also, thinking about placing a different cam in the power plant. Nothing too radical in cam modification and want to hear about ALL YOUR IDEAS REGARDING CAM MODIFICATION FOR A 1966 GTO THAT WILL RETAIN A HEALTHY SOUND & PERFORMANCE, BUT NOTHING LETS SAY EXTREME.


when i did mine, i used the 068 grind cam as Jeff recommended (n524 in the ames cat), a new timing chain and water pump, viton rear main seal, refreshed the heads ( lap valves and new valve seals), all new gaskets and added a original restored tripower . i'll let you know how it runs soon! good luck


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## geeteeohguy (Feb 2, 2008)

What JohnnyLightning said. In 1988, when I tore down the original engine in my '67 to overhaul it, it had 173,000 miles on it. I KNEW it must need an overhaul. (It had a burnt valve and was running on 7 cylinders.) Well, the thing looked like new inside, but I overhauled it anyway. Mistake. I should have just done the seals and timing chain, and a valve job. 121,000 miles ain't hay, though. When you go to reseal it, you can pull a rod cap and the main caps (you'll need to pull the main caps to do the rear seal) and look at the bearings and crank. Heck, you can even plastigage-check the clearences. If you're out of spec, rebuild the engine. If you're in spec, and the bearings and crank look fine, put an 068 cam in it, and a new chain, and run it. It all depends on the condition of the engine.


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## jetstang (Nov 5, 2008)

The original 350 I'm freshening up for my 70 had 100k on it when pulled. I pulled a piston out and it had .014 ring end gap, the spec is .010-.040. None of the rocker nuts have any crimp left, probably had a hell of time keeping it from ticking. 100K isn't much if the maintenance was done on it.

How do you replace the rear main seal, I read something about rolling it up in a tube for install, but am confused. Might as well put one in while I have it apart.


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## take5 (Aug 9, 2009)

geeteeohguy said:


> What JohnnyLightning said. In 1988, when I tore down the original engine in my '67 to overhaul it, it had 173,000 miles on it. I KNEW it must need an overhaul. (It had a burnt valve and was running on 7 cylinders.) Well, the thing looked like new inside, but I overhauled it anyway. Mistake. I should have just done the seals and timing chain, and a valve job. 121,000 miles ain't hay, though. When you go to reseal it, you can pull a rod cap and the main caps (you'll need to pull the main caps to do the rear seal) and look at the bearings and crank. Heck, you can even plastigage-check the clearences. If you're out of spec, rebuild the engine. If you're in spec, and the bearings and crank look fine, put an 068 cam in it, and a new chain, and run it. It all depends on the condition of the engine.


I have a very good engine building mechanic who will be working on the engine.
It will be interesting to see how the spec's check out. Engine oil and filter have always been changed at 3000 miles and correcting / improving what is needed will be done.
Thanks again for the "heads-up" on what to be on the look out for with engine restoration.


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## johnnylightning03 (Nov 27, 2007)

geeteeohguy said:


> What JohnnyLightning said. In 1988, when I tore down the original engine in my '67 to overhaul it, it had 173,000 miles on it. I KNEW it must need an overhaul. (It had a burnt valve and was running on 7 cylinders.) Well, the thing looked like new inside, but I overhauled it anyway. Mistake. I should have just done the seals and timing chain, and a valve job. 121,000 miles ain't hay, though. When you go to reseal it, you can pull a rod cap and the main caps (you'll need to pull the main caps to do the rear seal) and look at the bearings and crank. Heck, you can even plastigage-check the clearences. If you're out of spec, rebuild the engine. If you're in spec, and the bearings and crank look fine, put an 068 cam in it, and a new chain, and run it. It all depends on the condition of the engine.


:agree. my cylinders and bearings looked pefrect, however i knew how my dad drove and maintained the engine its whole life. most people i talked with said with 99 k on it to leave the rings and bearings be. i was recommened by a friend who has been a gm mechanic for the past 45 years to soak the tops of the pistons with gm top end cleaner to break up the carbon in the rings, which i did with the oil pan off. here are some pics of inside the motor. you can see how clean it was and that the timing chain was stretched. this was the first time the engine was ever apart and i felt it was better to keep it an original 389 bore and the crank std not undersized. the ONLY thing i noticed was one of the lifters was starting to hollow out. so in came the 068 and tri power idea . a rebuilder i spoke with even said to leave the oil pump alone as well and the consensus was that not much went wrong with these engines. more than one person told me to leave sleeping dogs lie. however i knew the history of my car, and i'm not going to race it. she ran well before i touched it with excellent oil pressure. lets hope it still does :rofl: :cheers


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## johnnylightning03 (Nov 27, 2007)

here are some more pics


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## topfuel67 (Dec 23, 2008)

Check out the Edelbrock performer cam. It has .420/.442 lift and very mild duration. It sounds like a ram air cam. It provides better fuel economy and more hp than stock. I put that cam in my 65 Tempest with a 65 389 and it was a great combo. There was a great article on the cam in a Classic Pontiac magazine I read a few years ago. They put it in their 65 GTO and compared it to stock. The article also mentioned to beware of cheaper cams that copy the specs. There's a lot of performance in the quality of the grind.


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## jetstang (Nov 5, 2008)

Why does such a small lift cam work in the Pontiacs compared to the lift in other motors? I understand with the later heads, 6X, with the bigger valves, but why does it work on the smaller valve heads? Is it the runner size? A mild SBC is .480 lift plus. Had a 302 Ford with 5.44 lift, and streetable.


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## 66tempestGT (Nov 28, 2009)

you have to take into consideration how the cam was actually measured. there is advertised lift and lift at .050


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## Rukee (Feb 8, 2007)

jetstang said:


> Why does such a small lift cam work in the Pontiacs compared to the lift in other motors? I understand with the later heads, 6X, with the bigger valves, but why does it work on the smaller valve heads? Is it the runner size? A mild SBC is .480 lift plus. Had a 302 Ford with 5.44 lift, and streetable.


Cause Pontiacs are better.


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