DISTRUBITOR!!

[chuck will]

Greetings from the Central Coast of CAlifornia. I am watching one of
God's miracles, a most beautiful sunset over the Central Coasts Pacific
Ocean. But with all the beauty comes much frustration with my GMC. I
must have a really bad distributor. I did all the test that the manual
and Emery told me to do and all indications are that both the main coil
and the pick up coil are shot. The two cost together about $ 70. or so
dollars. A newly rebuilt one at NAPA is 127.00 I know there is
somebody out there that does this type of work. Who is it? What is the
cost? and more important How long does it take? I would sincerely
appreciate any and all information on this subject. Yes it is on the
brand new engine. I knew something would go wrong. I can't believe I
got to New Mexico and back with only a ruptured CV boot. I honestly
believe I have a devil riding in this coach. Help is indeed
appreciated. Maybe some stories about your misfortunes with the GMC
would make me feel better too. I know some of you out there must of had
some really neat types of luck like me too~! Blessimgs Chuck

 

[dave markus]

[Admin note - "Bounced", non-member submission. Patrick]

>....I did all the test that the manual
>and Emery told me to do and all indications are that both the main coil
>and the pick up coil are shot.

It seems to me that it would be a bit unusual to have both coils fail at
the same time. How did you test them and what did you see?

>A newly rebuilt one at NAPA is 127.00

Is that one specifically for the GMC? If not, don't forget to change the
vacuum advance to a Delco 1973577 10 degree advance. I had pretty good
results using the 75 Toronado distributor (Cardone 1893) and a Delco
1973577 advance. The curves are very close.

>Yes it is on the
>brand new engine. I knew something would go wrong.

Given that you just overhauled your engine it is possible that something
did not get hooked up properly. I would check to be sure that the coil is
properly grounded. If not, the spark return will pass through the
pickup/module and will eventually cause a failure. Something else to check
is to be sure that you are using plugs gapped at .060 or less. The .080
plugs cause much higher voltages in the ignition system and will lead to
higher failure rates in the module, coil and rotor. Its also a good idea to
check for bad plug wires or corroded posts on the distributor cap or plugs.
Sometimes when this stuff is removed and re-installed a plug wire will
break or the connector in the wire will make poor contact at the plug or
distributor cap. The engine will still run OK because the HEI will
compensate by producing a higher voltage to jump the gap. But those higher
voltages are hard on the ignition system and will eventually result in a
failure.

>I honestly
>believe I have a devil riding in this coach.

I know the feeling. I have only been stranded a few times while on the
road. Two of those times where caused by GM HEI failures and the latest was
an ignition failure in my Jeep. I always carry a set of replacement parts
for the ignition (pickup, module, coil, cap and rotor) in my GMC.

>Maybe some stories about your misfortunes with the GMC
>would make me feel better too.

Well, my latest misfortunes with ignition systems was not in the GMC. It
was with my Jeep. After 130K miles I thought it would be a good idea to put
in a new distributor cap and rotor. I wasn't having any problems but I
thought it would be good preventative maintenance. About 5K later it
started intermittently running rough and missing. Eventually I could hardly
drive it at all. I finally narrowed it down to an intermittent ignition
coil. About 25K miles later it started doing the same thing. It was running
OK but it was missing under load. It was so intermittent that I couldn't
figure out where the problem was. I even thought that it could be the
transmission coming out of gear. I would loose power for a second and then
it would go back to full power with a hard jerk. As I was pulling out of
the driveway one night it just died. I towed it back to the house and found
that the coil was dead again. I thought that maybe it was that I had used a
cheap replacement coil so I went to the Chrysler dealer and got a new OEM
coil. That worked great for about a week and then it started missing again.
By now I started to think that something else was wrong and the coil
failure was a symptom rather than the cause. After looking things over I
found a bad plug wire. When I changed the cap and rotor the end of the wire
that attached to the distributor cap had broken. The spark jumping the gap
had corroded the connector on the wire and the post on the distributor cap.
This was causing very high voltages in the coil and probably lead to both
coil failures. I also noticed that the electrodes inside of the distributor
cap where coated with a thick layer of oxidized aluminum. I am sure that
this raised the voltage somewhat too. After replacing the wires and cap
things are working much better. I guess this is an example of a situation
where an attempt to prevent a failure actually caused a failure. The parts
I had used where after market parts (Standard brand) and where not the same
quality as the OEM parts. Its also an example of a situation where the
obvious failure was the symptom of the problem and not the real problem.

 

[dave1]

>....I did all the test that the manual
>and Emery told me to do and all indications are that both the main coil
>and the pick up coil are shot.

It seems to me that it would be a bit unusual to have both coils fail at
the same time. How did you test them and what did you see?

>A newly rebuilt one at NAPA is 127.00

Is that one specifically for the GMC? If not, don't forget to change the
vacuum advance to a Delco 1973577 10 degree advance. I had pretty good
results using the 75 Toronado distributor (Cardone 1893) and a Delco
1973577 advance. The curves are very close.

>Yes it is on the
>brand new engine. I knew something would go wrong.

Given that you just overhauled your engine it is possible that something
did not get hooked up properly. I would check to be sure that the coil is
properly grounded. If not, the spark return will pass through the
pickup/module and will eventually cause a failure. Something else to check
is to be sure that you are using plugs gapped at .060 or less. The .080
plugs cause much higher voltages in the ignition system and will lead to
higher failure rates in the module, coil and rotor. Its also a good idea to
check for bad plug wires or corroded posts on the distributor cap or plugs.
Sometimes when this stuff is removed and re-installed a plug wire will
break or the connector in the wire will make poor contact at the plug or
distributor cap. The engine will still run OK because the HEI will
compensate by producing a higher voltage to jump the gap. But those higher
voltages are hard on the ignition system and will eventually result in a
failure.

>I honestly
>believe I have a devil riding in this coach.

I know the feeling. I have only been stranded a few times while on the
road. Two of those times where caused by GM HEI failures and the latest was
an ignition failure in my Jeep. I always carry a set of replacement parts
for the ignition (pickup, module, coil, cap and rotor) in my GMC.

>Maybe some stories about your misfortunes with the GMC
>would make me feel better too.

Well, my latest misfortunes with ignition systems was not in the GMC. It
was with my Jeep. After 130K miles I thought it would be a good idea to put
in a new distributor cap and rotor. I wasn't having any problems but I
thought it would be good preventative maintenance. About 5K later it
started intermittently running rough and missing. Eventually I could hardly
drive it at all. I finally narrowed it down to an intermittent ignition
coil. About 25K miles later it started doing the same thing. It was running
OK but it was missing under load. It was so intermittent that I couldn't
figure out where the problem was. I even thought that it could be the
transmission coming out of gear. I would loose power for a second and then
it would go back to full power with a hard jerk. As I was pulling out of
the driveway one night it just died. I towed it back to the house and found
that the coil was dead again. I thought that maybe it was that I had used a
cheap replacement coil so I went to the Chrysler dealer and got a new OEM
coil. That worked great for about a week and then it started missing again.
By now I started to think that something else was wrong and the coil
failure was a symptom rather than the cause. After looking things over I
found a bad plug wire. When I changed the cap and rotor the end of the wire
that attached to the distributor cap had broken. The spark jumping the gap
had corroded the connector on the wire and the post on the distributor cap.
This was causing very high voltages in the coil and probably lead to both
coil failures. I also noticed that the electrodes inside of the distributor
cap where coated with a thick layer of oxidized aluminum. I am sure that
this raised the voltage somewhat too. After replacing the wires and cap
things are working much better. I guess this is an example of a situation
where an attempt to prevent a failure actually caused a failure. The parts
I had used where after market parts (Standard brand) and where not the same
quality as the OEM parts. Its also an example of a situation where the
obvious failure was the symptom of the problem and not the real problem.