[Greg Reid]

That's awesome. I switched to 3.55 gearing and it's a LOT more fun except on the interstate.
I still remember clearly my first drive after a 10 year restoration. I drove it 50 or 60 miles one way to the BOP show.
Somebody took this shot to commemorate it's debut. Most of the folks on this photo are PY forums members. I'm the one with the Band of Gypsies tee shirt.

Sent from my moto g stylus (2021) using Tapatalk

[locomotivebreath]

Now that’s a cool pic - I need a crew like that ! I work with some car guys but I’m definitely the Pontiac loner . I live in norther Kentucky by Cincinnati , lot of 50mph 2 lane country roads in the hills that those 3.90s seem pretty well suited for . I sure don’t down shift much ! I think those 28 inch tall tears tamed them down . Im only about 15 miles from edgwater drag strip - might take her for a run down 1/4 in the spring .

[Lemans64]

I also run 3.9 in my 64, mostly low speed country driving. But like you I run a tall tire in rear to help compensate for the 3.9.
I run a 255/70/15 during summer show season and during start or end of season I run a 245/60/15, you wanna play now, LOL.
Finds the RPM way faster with the 245's. 255's are 29 and 245's are 26.5 tall so it does change the ratio quite a bit.

[locomotivebreath]

I did some gear math and I think 3.55 with a 26 tire is about the same as 3.90 with the 28 . I could see a 3.55 swap as one of the few mods I’d do with this car . I’m pretty lazy to swap a diff these days though . I was going see what I liked & didn’t like when I got it back - like swapping gears , bigger sway bar , tubular control arms but it’s far exceeded my expectations . I have tubular rear control arms and frame reinforcements but that’s because the stock parts were pretty corroded . I added some creature comforts me & the wife like AC .

[PAUL K]

If the 3:90's don't bother you driving around I'd leave them in. Makes the driving experience much more fun!

With that said, ironically my best friend from HS brother has a Solar Red 68 GTO. He's owned it since the mid 70's and it was off the road when I met him (mid 80's). About ten years ago he got it back out and has been driving the heck out of it and racing a lot in a Pontiac racing series in Arizona. His car looks a lot like yours and has about the same stance and wheel and tire size combo. I remember him telling me about going back and fourth between the 3:90 and 3:55 gears back in the day. He said there wasn't much difference, the car just felt better going through first gear when he raced.

Great thread and glad you are excited about cruising the car around.... Enjoy!

[gtospieg]

Keep the 3.90's and put in a TKX 5 speed...you'll love the difference for highway driving.

[locomotivebreath]

The tkx is appealing , but I really like the old school parts for now . When I was 20 , I would’ve screwed up and had a performer intake , eddy carb , some black Jack headers and an a fireball cam ! I really appreciate the original parts on this car . Rear diff isn’t though , it’s an N unit , it had 3.55s - 2nd owner blew that rear . My chev buddies are everything has to b fuel injection , LS swaps . I don’t plan on selling this car , so upgrades are possible , im 45 so hopefully I get some time to care for it . This thing is a kick !

[Half-Inch Stud]

A 12-bolt posi rear could be such an upgrade. Save the N HSG rear for when your done driving it too hard.
But since you just go to driving the GTO, time to enjoy awhile, and address only the simple stuff:

Set Choke to work,
Tighten the Sun Visors and rear mirror set screws.
Get a Pontiac Vacuum Gauge

[Greg Reid]

I'd love to do an OD trans swap myself but it won't happen any time soon I'm afraid.

[locomotivebreath]

I can’t get this thing started for nothing ! I flooded it the other day and put fresh plugs in - still wouldn’t start . Then the battery ran down . Let it sit for a few days and put my jump pack on it - it coughed a few time but won’t catch . I didn’t pump it today , just set the choke . I was wondering if the Petronix went south already - it’s atleast 12 years old but has no real time on it .

[johnta1]

Is the carb getting gas? or flooding from stuck float?

[Greg Reid]

Put a timing light on one of the ignition wires to see if you're getting fire then go from there.

[1968GTO421]

In his posts Cliff Ruggles states that every Pertronix he has dealt with has gone bad. He recommends stock points system or HEI, I believe. FWIW

[locomotivebreath]

Yes he does , when I bought it , that was the go to recommended do- dad ! I’m charging the battery now and at work so I haven’t fooled with it . One thing though , when I would let go of the key it cough on a few cylinders - isn’t that the sign of a bad coil ? I might try to full with it tomorrow before work , atleast take some voltage readings .

[Bill Hanlon]

If it was a points system I'd check for 12v on the coil positive while cranking the engine. I don't know if that applies with Pertronics.

[Half-Inch Stud]

....got a spare tested HEI Dizzy (no cap and rotor) laying around.

[Greg Reid]

That trying to start when you release the key sounds like what happens when you have 12v in the ignition 'Run' position but have lost it in the ignition 'Start' position. Check the coil voltage while trying to start it. Then check it with the switch just in the on position.
Pertronix is a good suspect too. The only one I've had went bad after a year or so.

[locomotivebreath]

What would cause that - bad ignition switch ?

[Greg Reid]

It's possible that a switch could lose continuity in one position or a wire connection was lost to that part of the switch. It could also still be the Pertronix stuff. If you check the voltages in start and run you can verify or eliminate the possibility of that being the issue.

[locomotivebreath]

Ok , it has the harness in it without the resistor wire for the Petronix . I bought the Petronix around 2010 when I had the distributor rebuilt , it was well thought of then . I wasn’t afraid of running points , just getting quality points & condenser was becoming the issue . I have a barely used set & condenser that are about 45 years old ,- are they trust worthy ? Sun tuned said they held spark through 6500 rpm with the old coil .