Help With 1969 GTX 440 That Dies in Gear and Runs Rough Sometimes

dedline · Aug 30, 2020

Hello everyone. My dad and I are working on his 1969 Plymouth GTX. It has a 440 and a 727 transmission. The carburetor is an Edelbrock 1407 750CFM and the points have been upgraded to a Pertronix Ignitor 2. Here are the issues we have been having.

First, when you start it, it runs very rough and vibrates like hell. As soon as you give it a little throttle it goes away and runs nice and smooth. This only happens on startup. Here is a video of that problem:

Second problem, if you run the engine at about 2000 or 3000 rpm, the engine starts to surge up and down. You really feel it when you are cruising at about 30 MPH. But when you’re driving and giving the engine throttle, it runs great. No problem lighting up the tires.

And lastly, the most problematic, is that 90% of the time when you start the engine and you put it into any gear at IDLE, it instantly dies. If you mess with the timing either towards or away from TDC, the problem SEEMS to go away, but comes back almost instantly. We have tried adjusting the carbs mixture screws and distributor timing multiple times to no avail. We can’t figure out why its doing it. Any ideas?

Beekeeper · Aug 30, 2020

How long has the Pertronix distributor been in It?

dedline · Aug 30, 2020

Beekeeper said:
How long has the Pertronix distributor been in It?

We just installed them ourselves a month or two ago. We just bought the car in June, and immediately put the pertronix in. We bought the pertronix kit off of eBay.

Beekeeper · Aug 30, 2020

Have you ever ran it with the points distributor in it?

turbine68rt · Aug 30, 2020

When you say "adjusting" the timing, where exactly is it set? Find out how much mechanical advance you're getting at 2500 so you know how much initial you can have in order to get 34-36 all-in. If it needs more initial, you can get an fbo limiter plate to tailor the initial without having too much all-in. Is your choke functioning correctly? Have you taken a vacuum reading? When was the last time the carb was rebuilt? Any vacuum leaks?

PRND21 · Aug 30, 2020

Make sure your timing marks are correct, that the outer ring hasn’t slipped on your vibration dampener.

dedline · Aug 31, 2020

Beekeeper said:
Have you ever ran it with the points distributor in it?

Yes, when we bought it we drove onto the trailer with points. Seemed okay then.

turbine68rt said:
When you say "adjusting" the timing, where exactly is it set? Find out how much mechanical advance you're getting at 2500 so you know how much initial you can have in order to get 34-36 all-in. If it needs more initial, you can get an fbo limiter plate to tailor the initial without having too much all-in. Is your choke functioning correctly? Have you taken a vacuum reading? When was the last time the carb was rebuilt? Any vacuum leaks?

For the numbers, I will have to get back to my dad. We have a manual choke installed. Carb was installed by PO. Don’t know it’s status. We checked for vacuum leaks and couldn’t find any. And we have not taken a vacuum reading yet. I do have a meter though.

PRND21 said:
Make sure your timing marks are correct, that the outer ring hasn’t slipped on your vibration dampener.

Thank you. We will check this.

coloradodave · Aug 31, 2020

Dieseling refers to an engine that 'runs on' after you turn the key off. I would just call it running rough or missing... Sounds like the carburetor needs to be completely disassembled and cleaned out with carb cleaner and air pressure put through every orifice and passage. Did the car sit for a time with old fuel?

dedline · Aug 31, 2020

coloradodave said:
Dieseling refers to an engine that 'runs on' after you turn the key off. I would just call it running rough or missing... Sounds like the carburetor needs to be completely disassembled and cleaned out with carb cleaner and air pressure put through every orifice and passage. Did the car sit for a time with old fuel?

The car sat a least a few years when we got it. The PO’s husband had put the carb on it drove it a bit and I assume passed away, the it sat for a while. It ran okay the day we picked it up. Didn’t do any of the problems it has now. And that was with the old gas and points. We did have to prime the carb with fresh fuel for it to get going though.
And thank you for the comment on the word dieseling. I will modify my sentence to avoid confusion.

turbine68rt · Aug 31, 2020

Beekeeper said:
Have you ever ran it with the points distributor in it?

I prefer points myself......for the last 33 years.

toolmanmike · Aug 31, 2020

If it ran ok before and bad after you installed the new distributor that's where I would start. Clean and adjust the points at about .017 on the high point of the distributor cam. Install it again and set the initial timing at 10° or so. It should run fine. If it doesn't you can now look elsewhere. The carb could be nasty inside if it sat for a few years with old gas in it.

Beekeeper · Aug 31, 2020

dedline said:
Yes, when we bought it we drove onto the trailer with points. Seemed okay then.

I think I would stick the points distributor back in and see how she runs

Help With 1969 GTX 440 That Dies in Gear and Runs Rough Sometimes

dedline

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Beekeeper

It’s a disease without a cure!

dedline

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Beekeeper

It’s a disease without a cure!

turbine68rt

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PRND21

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dedline

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coloradodave

FBBO Gold Member

dedline

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turbine68rt

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toolmanmike

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Beekeeper

It’s a disease without a cure!

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