1968 GTO Resto-Mod

[1968 GTO Resto-Mod]

yesterday afternoon i ran the oil pump priming tool again for about 10 minutes, primed the fuel line, and started the engine.
writing this now, about 24 hours later, my heartbeat still hasn't completely stabilized.
when i turned the key the carb sputtered and burped for about 3 seconds before combustion took off.
i didn't even have my foot on the pedal but it ran up to about 4000 rpm in the following 3 seconds.
at that point i knew something was wrong so i turned the key off.
10 seconds into the operation the key was in the 'off' position but the engine was still running at around 4000 rpm.
i panicked.
the sound was powerful unlike anything i have ever heard in my entire life.
i switched the key back and forth a couple times with no effect, then i jumped out of the driver's seat and caught myself staring at the melting paint on the exhaust ports for about 2 seconds before disabling the ignition system.
when the engine finally stopped the shop was filled with smoke and i was on the verge of a full blown heart attack.

i do not know what happened.
i do know i have a lot to learn.

thanks for having a look at my thread.
danny

[fbrown540]

The key not turning the engine off actually happening fairly frequently back in the day when these cars were fairly new. The cause is generally a feedback loop that keeps powering the ignition. You can test for this by simply unplugging the wire to the alternator. If the engine stops with the key off and by unplugging the alternator wire, you have a feedback loop.

If you have a feedback loop, You could leave the alternator unplugged while you trouble shoot the high idle rpm.

Some causes are:

- lack of a resistor in the GEN light line.
- not properly converting the wiring when swapping from an external to internal regulator. This seemed to happen to many of my friends back in the early 70's.
- improper conversion from a points type distributor to a electronic one. Again this happened to many of my friends.

It been so long that I don't remember what was done to fix the problem, but the fix was very minor in all cases.

I don't know if this applies to your engine, but many GM engines of the 60's had a thin metal plate between the carb gasket and the manifold. Leave the metal plate out and the engine won't idle. I had seen many of my friends leave the metal plate out and couldn't get their engine to run very well.

Maybe someone with more recent experience will chime in.

[PBarkley]

Subscribing to this thread...and seeing your recent engine-related post has me on high alert for the same reason with my car, haha.

Glad to see another build staying Pontiac powered!

[1968 GTO Resto-Mod]

Originally Posted by fbrown540

The key not turning the engine off actually happening fairly frequently back in the day when these cars were fairly new. The cause is generally a feedback loop that keeps powering the ignition. You can test for this by simply unplugging the wire to the alternator. If the engine stops with the key off and by unplugging the alternator wire, you have a feedback loop.

If you have a feedback loop, You could leave the alternator unplugged while you trouble shoot the high idle rpm.

Some causes are:

- lack of a resistor in the GEN light line.
- not properly converting the wiring when swapping from an external to internal regulator. This seemed to happen to many of my friends back in the early 70's.
- improper conversion from a points type distributor to a electronic one. Again this happened to many of my friends.

It been so long that I don't remember what was done to fix the problem, but the fix was very minor in all cases.

I don't know if this applies to your engine, but many GM engines of the 60's had a thin metal plate between the carb gasket and the manifold. Leave the metal plate out and the engine won't idle. I had seen many of my friends leave the metal plate out and couldn't get their engine to run very well.

Maybe someone with more recent experience will chime in.

Originally Posted by PBarkley

Subscribing to this thread...and seeing your recent engine-related post has me on high alert for the same reason with my car, haha.

Glad to see another build staying Pontiac powered!

cheers guys- thanks for your input.
i really appreciate your comments!



the engine is running smooth tonight.
next time i should remember to verify correct throttle cable adjustment before start-up!
today i replaced the spark plugs and it started back up no problem.
still need to troubleshoot key not turning the ignition off.
also, there's a small coolant leak at the top of the water pump gasket and a small power steering fluid leak at the pump high pressure line out.



despite a few interesting unexpected challenges recently i've been making some good progress.
i'm happy to know the machine will run.
thank you for having a look at my project!
danny

[waynieZ]

Good to hear it's running good now. With the other posts you'll have some where to start looking for your run on problem.

[PBarkley]

I'd have to go back and look at your ignition setup, but I'm in the process of familiarizing myself with the MSD 6AL box I'll be installing (eventually) on my car and it mentions engine run on, similar to your situation when using the MSD box with a GM HEI distributor. Basically describes that there is some sort of signal that must be bypassed, otherwise the MSD box continues providing spark. Kinda leading me to just do my engine break in without the 6AL and wire it in afterwards.

Never know, but it might be a good place to start your gremlin hunt.

[1968 GTO Resto-Mod]

Originally Posted by waynieZ

Good to hear it's running good now. With the other posts you'll have some where to start looking for your run on problem.

thanks, wayne! it felt so good to see and hear that thing running smooth... for the first time in over 10 years!

Originally Posted by PBarkley

I'd have to go back and look at your ignition setup, but I'm in the process of familiarizing myself with the MSD 6AL box I'll be installing (eventually) on my car and it mentions engine run on, similar to your situation when using the MSD box with a GM HEI distributor. Basically describes that there is some sort of signal that must be bypassed, otherwise the MSD box continues providing spark. Kinda leading me to just do my engine break in without the 6AL and wire it in afterwards.

Never know, but it might be a good place to start your gremlin hunt.

thanks, peter! i've installed msd's pro billet distributor for v8 pontiac application.

the last time i started the engine there was a real high pitched squealing sound for about 5 seconds then it stopped and everything sounded fine.
after i killed the iginition i crawled under the car and saw that the pinion gear had been stuck in the engaged position after the engine started and the ring gear completely shredded it- spun it right off the starter motor output shaft.



i pulled the starter off, boxed it up, and sent it back to robbmc.
those guys are great... they said it's a pretty common problem and that they would be happy to fix it- no problem.
they also said it usually results from a problem with the wiring.
since then i've been doing a little snooping around in the dash wiring and i happened to find a ground wire that i failed to tie into the master ground kit at the firewall.
my hunch is that it provides ground to the ignition switch.
i wonder if this array of problems could have been caused by an improperly grounded ignition switch?
anyway, i'm going back through the wiring starting at the switch and having another close look at the wiring diagrams as well.
my hope is to have the wiring thoroughly inspected and to get any issues resolved by the time the starter gets back to me.

later today i'm meeting with straatsma to talk about the paint job.
he's going to look at the car and hopefully offer some advice regarding fitment/gaps/etc.

always moving forward!
thanks for your interest in my project, and thanks for having a look at this thread!
danny

[PBarkley]

Sounds like you're onto something! Good luck with the hunt!

[1968 GTO Resto-Mod]

well, it seems like it's about time for another update as quite a bit has happened since my last post here.

robbmc replaced the pinion gear and returned the starter motor to me and didn't even charge me a penny.
i can't say enough good things about those guys: great people, great products, and great service!
the run-on issue was in fact being caused by a feedback loop making it's way from the alternator back to the ignition circuit thru the exciter wire.
the guys at msd steered me toward a solution by informing me that the issue is covered in the instruction manual they provided with their ignition system... r.t.f.m. right?
i spliced a diode into the alternator exciter wire (per the msd instructions) and the problem is solved.
the ignition now starts and stops perfectly with no other apparent issues at this time.
unfortunately, while in the process of troubleshooting that problem the 'small' coolant leak i first saw after initial start-up turned into a 'large' coolant leak.
ultimately i had to remove the timing cover and spiff up the gaskets.



of course i was less than thrilled with this situation especially since i had just finished putting the front clip together, but in the end the whole operation only took me about half a day of shop time.

in other news i've been learning a lot about what it's going to take to get the various moldings and trim pieces test fit and installed properly.
all the rusty metal in the front and rear glass channels was removed and replaced and none of the original trim studs remain so i ordered a bag of them from eastwood and i'll borrow a stud welder from straatsma to install them.
i also need to drill new holes for the rocker trim clips and wheel well molding screws before the car goes to paint.

also, i've still been doing a lot of detailing and painting of small parts, running wire for the front and rear lights, preparing the rear bumper for installation, troubleshooting various minor electrical bugs, and continuing to install insulation and vibration dampening.





thanks for checking in on my progress.
apologies for not posting more often. regardless, i am always moving forward... even if sometimes it's a case of 'one step forward then two steps back!'
i'm trying my best to stay on top of this project and to keep mindful of the fact that for me it's more about the journey than anything else.
i can see that every little step along the way is a special part of this experience (even if it is a step backward) and i've been trying to train myself to learn to appreciate it all.
and to be straight-up there's even a little part of me that doesn't want this project to ever end. it's been such a big part of my life recently and i frankly don't really want it to be over. i sometimes find myself just spaced out standing in front of the car marveling at what it has become...
haha, sorry to wax sentimental here guys. it's just all pretty huge for a guy like me. i've never really done anything like this and i never thought i could ever pull this off, especially after everyone i talked to about it told me not to try and do it!









thanks again for having a look at my project and thanks to lateral-g for hosting this thread.
i am very fortunate to be able to share this project with this community!
cheers guys!!!
danny

[1968 GTO Resto-Mod]

Originally Posted by PBarkley

Sounds like you're onto something! Good luck with the hunt!

Originally Posted by PBarkley

I'd have to go back and look at your ignition setup, but I'm in the process of familiarizing myself with the MSD 6AL box I'll be installing (eventually) on my car and it mentions engine run on, similar to your situation when using the MSD box with a GM HEI distributor. Basically describes that there is some sort of signal that must be bypassed, otherwise the MSD box continues providing spark. Kinda leading me to just do my engine break in without the 6AL and wire it in afterwards.

Never know, but it might be a good place to start your gremlin hunt.

thank you very much for your insights as well!
you were right on.
lesson learned: start by reading the manual!
cheers,
danny