Hi, i'm new to the site and to 3rd gens, I have a 85 z28 with a 1974 350 swapped in it, it has a yellow/red wired Accel HEI supercoil and my problem is it keeps frying modules, ive gone throught the stock one, two OEM, and now an Accel module. My timing is set to zero degress, the engine does have an aftermarket cam unfortunatly i do not know the duration but it is small. Can anybody give me any ideas of whats wrong?


Thanks,
Tom

 

well
A) set at 0 is not good for an aftermarket cam.. ussaly you advance them
B) check the 5v refrance signal form the comp(if it's a comp controlled HEI)
C) you knew when timing an HEI car or any car mater afact you have to rule out any advancing messures.
ex. 5v ref form computer, vac adv. pod, mechanical & springs, so you don't have any advance on your BASE timing, all these will play a factor after you BASE timing is set.

as for the igniton module. i wouldn't say that you've had bad luck with that cause you've tryed diffren't brands. if you have a high discharged coil it very well could be blowing you swiching transistor or over loading it. try getting a good after market one.

just my .o2

 

Check these all

 

thank you both for the replys! is the switching transistor the plastic cover over the timing advance?

 

this is a comp controlled HEI right.. your switching transistor is what is in your module. you 4 point module. it gets a digital signal form you signial converter. which gets it sginal form the a/c pick up. all this does is make and break the ground for the coil to disgrage. . when the a/c pick up is alighted with the other reluctores it creats a magnetic feild which enduces electricty into the nearest condctor and you p.u coil is the closest so it sends a signal that is a a/c signal to the signal converter which then translates it into a digital singal which the switching transistor reads and then will complete the circut groudning the coil to build it's magnetic charge.. but when the car goes into closed loop a 5v ref. is sent to the module and goes though a coil. when electricty goes though wire it creats a megnatic field. then that pulls down swicth 2 which connects the ECM with the switching transistor. and tells it when to fire. based on the CPS.



after that said... what is exactly happening and how do you know it's the module going bad

 

The distributor is actually non-computer controlled, for whats happening, when i installed the accel i got everything put back together and it started right up, I ran it for about 15 to 20 minutes the shut it of and the about an hour later i stated it back up drove it out of my driveway onto the street where it idled for about 5 minutes it then started sputtering and died I got it started again but it kept dying and then just didnt start anymore, so i removed the modual and tested it with a mulitmeter and compared the read out from the other modules I had before. Could it possible have something to do with running that coil with a factory cap and rotor? if so what else do i need to replace in the ignition to solve the problem? thanks again for the help!

 

ok a non-cc HEI cap... test the coil.. you might have it hooked up wrong... check all the wireing mayb abad ground make sure everything is hooked up right. sorry about the module agian. what were the readings on it.?? and what pins this well help make it alot easyer. find a pic of the module. then just show which ones tested bad. i'll and others will be able to tell you then i'm gonna go take a look at my HEI cap right now.

 

Heres a read out from my previous module, I didnt record the accel before i returned it, but the accel was the same or lower
I used a digital mulimeter set to 200k OHMs

W+ to B- 63.5
W+ to C- 128.3
G+ to B- 73.6
G+ to C- 141.6
W+ to G- 9.9
B+ to C- 43.0
B+ to W- 55.4
B+ to G- 58.0

 

Are you coating the bottom of the module with Dielectric Thermal grease before installation? If not then this can overheat the module and cause failure.

Also make sure that you have installed a low resistance button in the cap. Shouldn't burn out the module, but a stock graphite button will get hot enough to melt the cap around the button.

 

That was going to be my question. Not regular clear dielectric grease, but the white goop. (Wells part no. SL203)

 

So did this problem just start happening out of the blue or did you change something?Was the car running fine before with that timing?
Make sure your grounding strap still there,its a metal tang that goes from under the coil,up and into the area in the cap where the rest of the wires join up.ive heard people throw these out or forget to intall em and leads to greaf.
http://www.off-road.com/chevy/review...e/CoilInst.jpg

 

Good point about the grounding strap...that could also do it.

 

Well after taking the coil off and looking it over i saw the yellow and red wires were crossed underneith the cover so i may have been installing them backwards, could that burn up the modual? if i did install them backwards would it still run?

 

Certainly isn't going to help matters. Yes car will run. It might be your problem with module burning. Also, did you apply Thermal grease to the bottom of the module and install the grounding strap and Terminal?

 

Yes, I applyed the white grease to the modual, im not sure where the grounding strap is located or what it looks like so im going to say no it doesnt have one!

 

After looking at your previous post, i dont have a ground strap on that coil!

 

That can't be good....

 

do you know if the accels came with them? is there anyway to get one or rig somthing up?

 

well from my inderstanding it is just a pice or wire mounted the the metle part of the coil the grouned to the neg on the coil.. i'm proablly worng

 

You re-use your stock ground.

 

The only problem is I bought the car with this coil so i dont have a stock ground

 

Auto wreckers, GM Dealership or local parts jobber. But get one!! You can also order them here:

http://www.kendrick-auto.com/ignition.htm

Part number: 40750 cost $1.93

 

In addition to the ground strap there is a short black ground wire that comes out of the coil (not all coils have this wire). That has to be grounded to one of the 4 coil hold-down bolts.

Also, there is a condenser (a capacitor- round metal thing with 1 wire coming out of it) on the floor of the distributor. They're cheap and I always replace them any time I change out the module.

 

just make sure if you replace the condensor that... you DO NOT have your self grounded to anythign ... you will most lilky die.. form a huge *** shock.. the condesor stores engery and when grouned it will relase it all.. so plz be carefull

 

Uhhh,,,that's a little bit exagerated...actually, hugely exagerated. Condensers ( Capacitor's ) are rated in " Farad's....how much amperage and voltage can be discharged in how short of a time. Car condensors are measured in " MicroFarads" ( millionth of a Farad ) and that is a very, very small amount of energy.

Simply put....the condensor in your car Distributor is not big enough...nor is it high enough voltage, to give you more than a mild " nip". It is also dealing with only small Primary voltages, as a stock HEI ignition is still an induction ignition, not a "Capacitor Dischage " ignition such as a Crane Hi-6 or an MSD unit. Big difference there as well. These capacitors are MUCH, MUCH bigger....and these may very well have the capacity to kill. The Mosfets on a Capacitor Discharge are even more dangerous. These have been known to kill. Fortrunately these are all sealed inside the unit, safely out of curious hands reach ( for the most part ). But the tiny condensor in your Stock HEI certainly does not have enough capacity to do any harm.

A Capacitor in the High Voltage section of a TV, Monitor or other very high voltage system with BIG Freakin' " Caps" is another matter.....you don't want to go near those. Those can kill....period.

More info:

http://electronics.howstuffworks.com/capacitor2.htm


PS: Worked for almost 20 years in Dealership parts departments. Back in the days of points and condensors. Favorite trick to get back at " Nasty" mechanics, was to charge up a Points Condensor on the Spark Plug tester. Instead of 12volts...you now had 20,000 plus volts stored up in this little puppy. Mechanic would get a really nice " shock" !!! when he picked this up .

But there was never any danger, because the condensor was so small and the amperage was in mill-amps. Nobody ever died from this that I know of....well not directly... ( Death from wrath of said Mechanic does not count )....and if this was done once it must have been done ten thousand times by Partsman and Mechanics all over the world. An " Old " trick.

Edit: Smiley in wrong place!!

 

Thanks for everbodys help, I will get a ground strap, I want to upgrade the cap and rotor and replace plug wires, then if all goes well my ignition should be in working order again!!