hemitheus
19? Plymouth Scampenstein
in converting to the gm HEI setup how do you know which is positive and which is negative on the coil? and also what is up with the 3rd connection?
HEI coil question
- Thread starter hemitheus
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hemitheus
19? Plymouth Scampenstein
heres a pic
BillGrissom
Well-Known Member
Sounds like you have just the coil shown below. I recommend getting your first parts at the junkyard. You would then have the factory cable shown from the 8-pin module to coil, plus the other connectors. Below shows the wiring. For more info, search the megasquirt site, which is where I found my info.
Re polarity of the Mopar pickup, you will have to try both to see which gives a more correct and steady timing. I haven't run the HEI setup on my slant yet, but will post when I figure it out. Twist the wires from the distributor to minimize cross-talk. Don't jury-rig spade lugs to the coil input, just snip the coil connector and wires from a GM distributor.
Re the 2nd Metripak connector, that is for optional computer control of timing. If you don't use it (unconnected) it runs with a fixed timing (limp home mode). GM mechanics routinely disconnect it during tune-ups. Holley's Commander 950 can connect to it. Of course, your Mopar distributor can control timing with its weights and vacuum module.
Re polarity of the Mopar pickup, you will have to try both to see which gives a more correct and steady timing. I haven't run the HEI setup on my slant yet, but will post when I figure it out. Twist the wires from the distributor to minimize cross-talk. Don't jury-rig spade lugs to the coil input, just snip the coil connector and wires from a GM distributor.
Re the 2nd Metripak connector, that is for optional computer control of timing. If you don't use it (unconnected) it runs with a fixed timing (limp home mode). GM mechanics routinely disconnect it during tune-ups. Holley's Commander 950 can connect to it. Of course, your Mopar distributor can control timing with its weights and vacuum module.
Bulldozer
free ice cream sandwiches
or...... you can check this out
http://www.forabodiesonly.com/mopar/showthread.php?t=203055
http://www.forabodiesonly.com/mopar/showthread.php?t=204177
http://www.forabodiesonly.com/mopar/showthread.php?t=203055
http://www.forabodiesonly.com/mopar/showthread.php?t=204177
hemitheus
19? Plymouth Scampenstein
i will need to post up a pic of what i already got at the scrapyard as it doesnt match the 8 pin and id rather build my own than buy a kit
Bulldozer
free ice cream sandwiches
that was more or less so you could see how the 8 pin is wired for reference in case you run into the parts .....
hemitheus
19? Plymouth Scampenstein
Oh, I see.
coil is out of a 98 GMC and has the coil to dis cap port then the weather-sealed 3 pin connection
but i have the older style 4 pin GM module
coil is out of a 98 GMC and has the coil to dis cap port then the weather-sealed 3 pin connection
but i have the older style 4 pin GM module
Here are the pin outs for the coil & module you have:
[ame="http://www.airtexve.com/custom_searches/showdiagram.php?file=ignition_coil_sheets/airtex/AT17.pdf"]Coil [/ame]
4 Pin GM ICM
.
[ame="http://www.airtexve.com/custom_searches/showdiagram.php?file=ignition_coil_sheets/airtex/AT17.pdf"]Coil [/ame]
4 Pin GM ICM
.
BillGrissom
Well-Known Member
I haven't seen the 98 coil before. I am guessing they didn't use the 4-pin module then.
To answer khaley71's question, the 8-pin module is found in GM V-8's w/ throttle body injection (TBI), which was maybe 1985 to 1995 in trucks and maybe 1993 in cars (Camaro, ...). Terms to search are "small cap distributor", "computer distributor", "external coil". The module was built into the distributor, as shown below. The green and white wires are the timing signal. Snip them close to the pickup to get the special connector. Also get the Metripak connectors and wires. I also grab the knock sensor and module since some after-market ECU's can use in spark timing (Holley Commander 950, Megasquirt), or you could have it just light a warning LED.
To answer khaley71's question, the 8-pin module is found in GM V-8's w/ throttle body injection (TBI), which was maybe 1985 to 1995 in trucks and maybe 1993 in cars (Camaro, ...). Terms to search are "small cap distributor", "computer distributor", "external coil". The module was built into the distributor, as shown below. The green and white wires are the timing signal. Snip them close to the pickup to get the special connector. Also get the Metripak connectors and wires. I also grab the knock sensor and module since some after-market ECU's can use in spark timing (Holley Commander 950, Megasquirt), or you could have it just light a warning LED.
hemitheus
19? Plymouth Scampenstein
bohica... thanks. that is good to have. I am looking to find out which of the 3 prongs go where. like on the diagram you showed. which is + which is - and what is the 3rd one?
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