Thread: ignition problems

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No harm / No foul... adding value?? Your participation is value enough!

As the kids used to say, Chill Out! It's all good..

Ditto what 34-40 said rspears, you add more than you miss!

hey guys its papajoe again. Put a new alternator in and have 14.5 volts going to the battery.took it for a run and it ran great ran it for about a half hour volt meter said 14.5 volts. Started it uo tonight and it fired right off. Went for a drive about 15 minutes into it slowly shut down started coughing and quit don't know where to go put a brand new module in yesterday...Take any help I can get. its a 350sb mild cam bare bones..DUI dist. New everything..Cant seem to get a handle on it!!!!!

Joe, in the other thread that you posted on MikeP went through his HEI, and the problem he described sounds exactly like what you're experiencing with yours.

Originally Posted by MikeP

I found what I figured I would, a broken wire between the pickup coil and the module plug. As the pickup coil is stationary and the module is attached to the breaker plate the wires flex as the breaker plate moves back and forth. In this case the flexing eventually caused the wire to break, at idle with the wire relaxed the 2 ends of the broken wire made contact, but when vacuum was applied and the breaker plate rotated the wire pulled apart.

Do you have a book on that distributor, so that you're confident pulling it apart and putting it back together? I'd say you're to that point, or else shopping for a replacement distributor for it. Then you can post mortem this one at your leisure, and have it as a shelf spare, or for the next build.

Do you have a electronic tach connected to the distributor? If so, disconnect the tach wire at the distributor and try it. A bad tach will cause all kinds of trouble with HEI.

You have a situation where the higher degree of spark is IONizing the air inside the dist cap-------was a common (well not too common) problem when the MSD 7 units came out and were run on engines up around 10000rpm. With the air ionized the spark just went all over causing some of what your discussing--------


On a race engine it was easy fix to just drill 8 1/2 inch holes between all the terminals however on a street engine this isn't a very good fix because of everyday street conditions----

Had a similar thing happen on several cars back in the 80's that had HEI. Would run great and then run crappy. I would take the cap and rotor off to look at the module or change the module. All would be great for a while then it repeated. Eventually every car that did this died. On one, I started looking at the rotor....under the contact for the center, there was a tiny hole eroded. There was some faint carbon tracking thru the hole that grounded the rotor to the distributor shaft thru this hole.....it seemed to be heat related to the conductivity... and related to me removing the rotor to change the module....I would destroy the carbon path and it took a drive to re-establish it. I also found that cheap crap rotors were the worst, real Delco rotors (the whitish ones) were the least susceptible to the problem. I talked to a couple of shops who admitted to making quite a profit by changing rotors but charging for a module. Also, look at the cap inside for tracking....it is really faint.
Mike in Tucson

An absolute must is a cap and rotor of high dielectric strength. For those of you who aren't familiar with that term it merely means components that are constructed of material that has a high opposition to current flow. MSD and other quality manufacturers, I assume, are you sort sort of bakelite material for their caps and rotors.
This will explain it much better than I can.
https://en.wikipedia.org/wiki/Bakelite

And I'll keep beating this old problem, make certain you have good grounds, engine to chassis, chassis to body, body to battery, battery to chassis, battery to engine. There is no such thing as too many grounds on a car or truck.

.

Roger that, Tech - I have a #6 directly from the negative post on the battery to a ground bar under the dash where I make all ground connections. This is in addition to a pair of straps between the body and frame, and two from engine to frame. Need to attach to bright shiney metal as well - paint (especially powder coat) is a great insulator.

By the way, ACCEL components are in the "worst" category for dielectric longevity. I am surprised that Accel stuff makes it home from the store before dying.

thanks for the input guys..i have tried all the suggestions, even made a list put a new summit mod in last night and it quit in about 15 min then would not start at all pulled it out and had it tested, it was bad this was mod 6 cant afford to keep throwing mods at it..uhave checked everything you guys have suggested, disconnected the tack today and will see what happens tonight ...again many thanks papajoe

Joe, what type of compound are you using between the module and the mounting surface on the distributor?

Have you contacted DUI products about this?

Have contacted DUI company about moduels...As you would expect they have never had any proplems with their distributors..go figure..