[KGTO]

Close friends of mine have asked me to go through their GTO, its been in the family since new. Seems to have about 115k on it and to their knowledge the engine/trans has never been out. Plan is to keep things mild and keep the overall integrity of the car in tact, but some performance upgrades. I've built a lot of high performance Pontiacs in the past, so I may have to keep myself "reigned" in....

Would like some thoughts, suggestions. The car actually runs pretty well, has some leaks which is what led to this.

Engine: 400 YS factory A/C (works)

Pull pan and heads. Send out heads for rebuild, guides, hardened seats, seals and springs (based on cam) and a light port match. May upgrade to roller rockers, Inspect cylinders and assess.

Replace rear main, with BOP viton, though I've heard the Best graphite seal might be better in this application. BOP pan gasket, pull caps and inspect bottom end. Would like to pull rotating assembly, inspect rings and debur block. They may want a little bit of cam, I was thinking a RAIV grind and keep the 1.5 rockers. I've never used one of these but thought it might be appropriate. Replace timing chain and all that, I don't think they were expecting a full rebuild, but honestly at this point if it has those miles, it probably makes sense.



Tranny TH400:

Send out for rebuild, nothing crazy here. Probably replace the converter with one a little more performance orientated. There has been an issue with the feel of the shifter and the neutral safety switch sometimes prevents starting. I don't know yet where the problem is, I suppose it could be in the column or all the parts are just worn.

Rear diff:

Has 3:23 open carrier, they want more gear. Doesn't see highway use and they were asking for 4:10s which I said is too deep. I suggested 3:55 or 3:73. TruTrac posi and replace all the bearings, seals.

Carb:
I'd like to send the original Rochester out to be gone through. I thought there was a member here who specialized in them. These are one carb I know almost nothing about and I think we should keep it, same with the intake, probably light port match and might block the exhaust passage.

Exhaust:
Swap to the Ram Air manifolds from RA Restoration, full 2.5" exhaust and go back to splitters on the rear. The stock heat duct assembly to the dual snorkel air cleaner is still intact. Will the heat riser fitting for the log manifolds work with the RA manifolds? It looks like it should.

Ignition:
Convert to Pertronix, otherwise adjust curve once running.


That's basically it, going to spec out some billet Ralley IIs in 15" nice and wide in the rear, and something a little wider in the front. Replace the carpet, few little other things.

Anyhow, thoughts or suggestions? Thanks!

[25stevem]

Just to let you know and keep you on the rails here with this , in 1970 when you ordered the 400 RA IV package you where mandated to have 3.90 rear gears and you could not get AC in the car.

[Scott65]

An 068 cam with 1.65 rockers and keep the 3.23 gears probably would be better. If these folks need someone else to do the work, keeping a RAIV type engine in good tune could be an issue...

[jhein]

Originally Posted by Scott65

An 068 cam with 1.65 rockers and keep the 3.23 gears probably would be better. If these folks need someone else to do the work, keeping a RAIV type engine in good tune could be an issue...

Good points. So they are obviously looking for more performance. The question is how much more and what are they willing to put up with. If they want more power but do not want a fussier motor then maybe a stroker crank and milder cam? That would make it friendlier for the auto trans and AC. For such a mild build, a new cast stroker crank only adds about $400 to the project and would be perfectly fine for that power level.

[68WarDog]

The suspension components are 53 years old. The body and suspension bushings are worn out and shot, and should be replaced if the car is going to be driven on a regular basis ,or expect a very harsh driving experience. So replace the front and rear control arms and trailing arm bushings, understanding that the owners may not want to do a body off frame bushings replacement at this time. I replaced my 70 components with polyurethane and it made a world of difference in both handling and riding comfort. I'm assuming the car has front disc brakes already.

[KGTO]

Just to clarify, it's not a RAIV. It's the 350 HP 400 (YS). They wanted a bump in performance and the RAIV is "small" in my terms, sounds good, a favorite among Pontiac people and will give them an increase in power. Obviously other grinds exist that may work a little better. Something nostalgic about the grind.

There is the chance they will want to go through all the bushings/suspension but not yet. I think they are planning to do a repaint later. ...and let's face it, these things blow up. He has a 68 Camaro that was an older restoration, did an LS swap and then progressed into a $175k build. She doesn't want that kind of build haha.

[JLMounce]

Originally Posted by 68WarDog

The suspension components are 53 years old. The body and suspension bushings are worn out and shot, and should be replaced if the car is going to be driven on a regular basis ,or expect a very harsh driving experience. So replace the front and rear control arms and trailing arm bushings, understanding that the owners may not want to do a body off frame bushings replacement at this time. I replaced my 70 components with polyurethane and it made a world of difference in both handling and riding comfort. I'm assuming the car has front disc brakes already.

I second this. While some performance bump in power is fine, that does very little for the overall driving experience.

I would focus on the driving experience first. Rebuild the suspension and steering including things like brake boosters, power steering pumps etc. where applicable. Make the car, true and easy to drive from a mechanical standpoint.

If you're replacing the carpet, you're likely going to find the original sound treatment is basically non-existent. Take it down to the floor pan and get proper sound and heat insulation in there. Either new factory stuff, or aftermarket.

Make sure all the electrical works and the HVAC work as intended.

Then I would focus on those performance bumps. Until you can meaningfully drive the car, that added 30-50 hp doesn't mean a whole lot.

[Scott65]

Originally Posted by JLMounce

I second this. While some performance bump in power is fine, that does very little for the overall driving experience.

I would focus on the driving experience first. Rebuild the suspension and steering including things like brake boosters, power steering pumps etc. where applicable. Make the car, true and easy to drive from a mechanical standpoint.

If you're replacing the carpet, you're likely going to find the original sound treatment is basically non-existent. Take it down to the floor pan and get proper sound and heat insulation in there. Either new factory stuff, or aftermarket.

Make sure all the electrical works and the HVAC work as intended.

Then I would focus on those performance bumps. Until you can meaningfully drive the car, that added 30-50 hp doesn't mean a whole lot.

A lot of truth in this. I'm always amazed when I drive Dad's stock original 65 GTO what a fantastic driver it is. Just a great running car from right off idle to redline. It's had the ignition curve optimized, but otherwise stock 389, likely with an 067 cam(never had the engine apart to verify)and a 2 speed auto with 2.93 gears. It has the normal early a body handling deficiencies, but overall a great driving early musclecar. More isn't always better, especially for a driver.

[Charlie Brengun]

Don't do the pertronix conversion on the distributor, either leave it stock with a recurve or get a quality hei style replacement would be my 2 cents..

[KGTO]

All good points, which I agree with.

However, the entire reason this is being done is to address oil leaks. So the engine and trans are coming out and seems prudent to do what needs done at that point. There is no hesitation to address suspension and other components, it just may hold until the winter. The shocks and springs have been replaced in the past year, the car actually drives very well, sees little use and they want to use it this summer.

[25stevem]

Another thing to be prepared for is that I have found many times with motors that have over 80k miles on then that you may not just be able to seal the leaks and stuff a new cam in because the cam bearings are coming a part.

Changing them with the block in the car is a nightmare!

[KGTO]

Originally Posted by 25stevem

Another thing to be prepared for is that I have found many times with motors that have over 80k miles on then that you may not just be able to seal the leaks and stuff a new cam in because the cam bearings are coming a part.

Changing them with the block in the car is a nightmare!

Yes great point, I've already told them we are likely looking at a full rebuild.

[MatthewKlein]

Originally Posted by KGTO

Tranny TH400:

Send out for rebuild, nothing crazy here. Probably replace the converter with one a little more performance orientated. There has been an issue with the feel of the shifter and the neutral safety switch sometimes prevents starting. I don't know yet where the problem is, I suppose it could be in the column or all the parts are just worn.

Rear diff:

Has 3:23 open carrier, they want more gear. Doesn't see highway use and they were asking for 4:10s which I said is too deep. I suggested 3:55 or 3:73. TruTrac posi and replace all the bearings, seals.

I'd be tempted to swap in a 700r4. They have a deeper 1st gear ratio of 3.06 vs 2.48 in the 400 trans

3.23 x 2.48 = 8.01
2.23 x 3.06 = 9.88
9.88 ÷ 2.48 = 3.99

Effectively it will launch like the 4.10 they wanted but cruise down the highway with 25% less rpm

[VCho455]

I built a YS motor with 62 heads 30 years ago. RA VI cam, 1:6 roller tip rockers, Rhoads lifers, 3 tube headers, stock intake with 1" spacer under the Qjet and a set of TRW forged pistons set at a zero deck. Used the stock distributor with a Pertronix and a proper curve. I pocket ported the heads and matched the intake.

The car ran 12.90's at 3800 pounds for years. Somewhere I have a couple of shoe boxes of time slips from that set up. It was also my daily driver. Fast, simple and reliable. The car has over 300k miles on it and over 120k miles with that engine. Been driven from coast to coast and from North Idaho to Texas.

Now days the engine resides under the work bench in the shop as the need for the car to be quicker was strong and more cubic inches was the solution.