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post #16 of 32 (permalink) Old 04-17-2019, 07:58 PM
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Re: New carb time...

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Originally Posted by DesertXL View Post
Hello My67Galaxie,

Your distributor is an aftermarket GM first generation HEI made to fit a Ford engine. The module is at the base of the distributor inside under the rotor. The hump in the cap is the ignition coil. I've never known a first gen General Motors HEI module to have intermittent problems, but there is always a first. Just make sure the carbon button on the inside of the cap is present and pressing down enough to touch the top conductive metal tang on the rotor. Whilst you're in there you might as well check to make sure the mechanical advance portion is free and not frozen due to rust or hardened grease.

A lot of folks like this GM ignition setup because it's compact and doesn't require the use of a resistance wire unlike the vast majority of Ford Duraspark electronic systems. The only exception are the mid to late 70's California emissions Ford Duraspark ignition module with the red sleeve (versus the common blue). That system requires no resistance wire with the correctly mated ignition coil.

Good luck.

Cheers
With all due respect...

Ahhh, but I have.

Those 1st gen GM HEI modules have a weakness.

The wires from the module that exit the dist housing, they flex inside the housing whenever the vac advance moves.

The actual wire strands break INSIDE the insulation and make intermittent contact.

The symptom of accelerating and having the engine die is because when you tip into the throttle,
the vac advance moves flexing the wires, and the wires lose connection.

Then by luck, or the moon and stars, the wires come back into contact and the engine fires up again..... until the next time...

Eventually they completely lose contact and of course... the engine won't run.

ANYTIME you have an intermittent running engine with a GM HEI...

CHECK THOSE WIRES.... very carefully, because the break is inside the insulation and the wire will "look fine"... but it's not.

I have run into this so many times over the years it's not even funny anymore.

Last edited by galaxiex; 04-17-2019 at 08:07 PM.
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post #17 of 32 (permalink) Old 04-18-2019, 07:00 AM Thread Starter
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Does this cause the raw fuel?
The hard starts and the simply shutting off when i come to a stop??

How do you check for broken wires if its inside the insulation??
Is there a replacement that i can simply unplug and buy new and just plug back in?
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post #18 of 32 (permalink) Old 04-18-2019, 08:38 AM
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Re: New carb time...

Quote:
Originally Posted by galaxiex View Post
With all due respect...

Ahhh, but I have.

Those 1st gen GM HEI modules have a weakness.

The wires from the module that exit the dist housing, they flex inside the housing whenever the vac advance moves.

The actual wire strands break INSIDE the insulation and make intermittent contact.

The symptom of accelerating and having the engine die is because when you tip into the throttle,
the vac advance moves flexing the wires, and the wires lose connection.

Then by luck, or the moon and stars, the wires come back into contact and the engine fires up again..... until the next time...

Eventually they completely lose contact and of course... the engine won't run.

ANYTIME you have an intermittent running engine with a GM HEI...

CHECK THOSE WIRES.... very carefully, because the break is inside the insulation and the wire will "look fine"... but it's not.

I have run into this so many times over the years it's not even funny anymore.
Hello galaxiex,

Thank you for posting that. I guess as the old cliche goes, your mileage will vary. None of my car chums who sported that style GM HEI never had problems nor I with a similar distributor that's been on my early 70's Caprice Classic for 20+ years now and still working just fine.

The wires in mine are a silicone high strand count and very flexible, similar to lab grade test leads. I wonder if certain OEM years or indeed certain aftermarket suppliers cut corners with the wiring at some point.

But I can definitely imagine intermittent problems if you're seeing breaks in the wiring.

Cheers
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post #19 of 32 (permalink) Old 04-18-2019, 09:09 AM
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Re: New carb time...

Quote:
Originally Posted by DesertXL View Post
Hello galaxiex,

Thank you for posting that. I guess as the old cliche goes, your mileage will vary. None of my car chums who sported that style GM HEI never had problems nor I with a similar distributor that's been on my early 70's Caprice Classic for 20+ years now and still working just fine.

The wires in mine are a silicone high strand count and very flexible, similar to lab grade test leads. I wonder if certain OEM years or indeed certain aftermarket suppliers cut corners with the wiring at some point.

But I can definitely imagine intermittent problems if you're seeing breaks in the wiring.

Cheers
Yes, that is the key thing, good quality flexible wires.

The early oem modules had very coarse and stiff wires, and as you can imagine,
they are very troublesome.

GM did upgrade the modules with better quality wires later in production,
and AFAIK the aftermarket modules have decent wire as well,
tho these days with cheap MIC parts.. who knows what you will get.

As mentioned, I have seen this issue many times over the years, tho not lately...

Probably my first encounter was approx 1979 or so.

Customer vehicle we did auto trans overhaul, TH-350, (I am trans rebuilder going on 40+ years)
Got trans installed and didn't work right.
Problem was vacuum issue. Lotsa vacuum leaks. (auto trans requires good vacuum to modulator)
Got vacuum leaks fixed and now dist vacuum advance started working... annnnd...
Now engine won't run properly.
Dies when you tip in throttle and vac advance moves. Start and idle ok.

Before, with vacuum leaks, dist vac advance was not working.
We fix leaks... vac advance (and tranny) works but engine dies.

Go figure... ALL things are related, when trouble shooting engine (or any) problem,
all aspects of complete system must be considered.


Last edited by galaxiex; 04-18-2019 at 09:14 AM.
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post #20 of 32 (permalink) Old 04-18-2019, 09:23 AM
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Re: New carb time...

sounds good , but i think you are confused about how vacuum advance works. it's source of vacuum is independant of manifold vacuum, where you found leaks
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post #21 of 32 (permalink) Old 04-18-2019, 09:55 AM
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Re: New carb time...

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Originally Posted by extech View Post
sounds good , but i think you are confused about how vacuum advance works. it's source of vacuum is independant of manifold vacuum, where you found leaks
Not confused at all...

This car had multiple vacuum leaks and cracked hoses.

We fixed them all.

Yes.... I understand that many engines use ported vacuum (above the throttle plate) for the dist vac advance....
(BTW... it's not really "independent" vacuum, it still uses engine vacuum, just not until the throttle opens)

... but "some" use manifold vacuum to the dist vac.

The "tip-in throttle, engine die" problem is because dist vac was hooked to ported vac,
which is "0" vac at idle and gets vac when throttle is moved off idle.
Thus moving the module and wires, and breaking connection so... engine dies.

The trans, of course, uses manifold vac.

Last edited by galaxiex; 04-18-2019 at 09:59 AM.
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post #22 of 32 (permalink) Old 04-18-2019, 06:38 PM Thread Starter
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You guys are waaay ahead of me in knowledge.. ive not had to work on ANYTHING more mundane than oil changes and breaks... matbe a few trans line's in the past 25 years..

So anyway.. i get home tonight and thought id just look around at things till it got too dark to see..

I pull the cap.. and look at the rotor.. kinda looks like it's " burnt" a little.. and the inside of the cap where the rotor spins looks like it actually has groves where the current passes..
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post #23 of 32 (permalink) Old 04-18-2019, 06:39 PM Thread Starter
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So I take some sandpaper clean up the rotor and the contacts inside the distributor cap the best I could in the dark threw it back together fired it up and it idled beautifully drove it down the road shifts very crisp into 2nd and 3rd gear idles great take it to the gas station drove it around put probably 5 to 6 miles on it before I came home if performed flawlessly then I guess that's where I just get lost as I could do the same thing tomorrow and it would fall on its face
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post #24 of 32 (permalink) Old 04-18-2019, 06:40 PM Thread Starter
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That is the model number of the Holley carburetor if that helps anybody help me
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post #25 of 32 (permalink) Old 04-19-2019, 07:05 AM
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Quote:
Originally Posted by extech View Post
vacuum advance works...source of vacuum is independant of manifold vacuum, where you found leaks
Good call.

Putts drives a 1965 customized Galaxie. Rebuilt 390, 4100 electric choke on a Performer, MX, AC, PS, PB w Scarebird front discs on Cragar 17" S/S.
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post #26 of 32 (permalink) Old 04-19-2019, 07:58 AM
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Re: New carb time...

Quote:
Originally Posted by My67Galaxie View Post
So I take some sandpaper clean up the rotor and the contacts inside the distributor cap the best I could in the dark threw it back together fired it up and it idled beautifully drove it down the road shifts very crisp into 2nd and 3rd gear idles great take it to the gas station drove it around put probably 5 to 6 miles on it before I came home if performed flawlessly then I guess that's where I just get lost as I could do the same thing tomorrow and it would fall on its face
Hello My67Galaxie,

You did well in just cleaning up the contacts, although from the pictures it didn't look that bad and just normal wear. The big thing would be wiping down the interior of the distributor cap especially between the spark terminals as you can get carbon tracking and spark jumping to adjacent cylinders prematurely causing problems.

You asked earlier about which wires could break, those would be the wires off the magnetic pulse generator (ie trigger coil) under the centre portion of the mechanical advance weights. Speaking of those weights they look like they could use some cleaning on the pivot points and a light application of synthetic grease to keep them from binding and corrosion setting back in.

The hardest part with intermittent problems is finding the root of the problem especially when it's running fine. Those kinds of intermittent problems are usually confined to either fuel system or ignition system. The only thing I can say is you'll have to wait till it acts up again or blast the car with the parts cannon ($$) in hopes you replace the intermittent part.

The next time it acts up whilst it's home you can always put the timing light on #1 cylinder and observe the lamp flashes against the timing mark on the harmonic balancer. If the lamp pulses are erratic or jumping around timing wise you know at least A problem resides in the ignition system. If the timing is consistent and stable and the engine is running poorly then you can focus on the fuel system.

Otherwise you are just guessing. And I don't recommend loading the parts cannon up and firing it at the car. As they say, work the problem, don't make it worse by guessing.

Feel free to report in with any findings.

Cheers
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post #27 of 32 (permalink) Old 04-19-2019, 11:29 AM Thread Starter
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XL thanks,,
I'LL get into that tommorw as its my only day off..

So just how do you go about cleaning them up ?
Do you actually take the small springs off??
Im gonna go ahead and grab a new cap and rotor tommorw too..
Would it be wise to get a new ignition module while im in there??

And do i tell them at the parts counter its just a standard GM hei distributor?
Thx again for the advice guys. Its much appreciated.
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post #28 of 32 (permalink) Old 04-19-2019, 11:00 PM
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Re: New carb time...

Quote:
Originally Posted by My67Galaxie View Post
XL thanks,,
I'LL get into that tommorw as its my only day off..

So just how do you go about cleaning them up ?
Do you actually take the small springs off??
Im gonna go ahead and grab a new cap and rotor tommorw too..
Would it be wise to get a new ignition module while im in there??

And do i tell them at the parts counter its just a standard GM hei distributor?
Thx again for the advice guys. Its much appreciated.
Hello My67Galaxie,

Yuppers you simply remove the springs and then remove the flyweights. I'd take a brass or light stainless steel brush and clean off the pivot points, then apply some synthetic grease. You already have a good picture for reference upon reassembly.

It wouldn't hurt to have another module that you can keep in the trunk as a spare, but if it's working I'd say it isn't imperative at the moment.

You can try your luck and ask for a 4 pin GM HEI but chances are most folks working behind the counter now-a-days wouldn't know where to go with that. You're better off asking for an ignition module for a 1975 Impala with a 350. I mean you can use your imagination as just about every GM mid year '74 and on came with it.

Cheers
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post #29 of 32 (permalink) Old 04-20-2019, 12:49 AM Thread Starter
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Thanks again everyone. Ill post more on the results.
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post #30 of 32 (permalink) Old 04-20-2019, 04:12 AM
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Is this the HEI you all are talking about?
https://www.amazon.com/dp/B071HMQFFC...v_ov_lig_dp_it

Putts drives a 1965 customized Galaxie. Rebuilt 390, 4100 electric choke on a Performer, MX, AC, PS, PB w Scarebird front discs on Cragar 17" S/S.
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