GM 8 pin HEI Conversion pics
A few weeks ago I decided I was going to end up with a high energy ignition system in my 73 Dart.
Took me a few weeks of planning in my time off here and there, and lots of investigation of schematics for different coil models and designs.
At first I was going to use the four pin module like most people that have done it, but an 8 pin module was suggested by (sorry, don't remember) but it was a fellow FABO member.
That got my curiosity up, so I chked into the 8 pin modules and what made them different or better than the four pins.
Come to find out that they are not really different aside from the computer controlable chip in them that allows the module to change the ignition timing when the engine needs it to adjust for elevation, change fuel mixtures and RPM changes, as well as engine load changes and the ability to hear and preignition knock and adjust the timing to correct it. (Some EFI packages such as the Mega Squirt use an 8 pin HEI module to help manage the fuel system)
Well, my car will never have a Mega Squirt EFI system so I don't really need the 8 pin module for a mostly stock 73 carbed 318 and the four pin would have been just fine.
Normally the computer in a newer car or truck controls the 8 pin module to handle the varying needs of the engine for ignition timing, but we dont have that computer in our old Mopars so what is the point of having the 8 pin module when the four would do the same job? Right?
I decided on the 8 pin so I would know how to set it up mostly because of this little peice of inginuity, http://www.rabidgator.com
Thier website is not functional yet, but the pdf document that desribes the product can be gotten here. [ame]http://www.letsgocomputers.com/docs/timingcomputer.pdf[/ame]
If you need Adobe's Acrobat Reader to view this document, it can be downloaded free here. http://www.adobe.com
This product looks like it would an invaluable addition to the HEI system.
It Looks like most any other guage, but these are some of it's fuctions.
1. Can set base timing, max timing, and even the advance curve all from the guage on the dash.
2. Has built in rev limiter as well as a shift light with user definable settings.
3. Has the ability to automatically retard the ignition when using boost, by sensing manifold vacuum and pressure.
It is able to do this only through the 8 pin module via the extra for pins that control timing.
This is why the 8 pin ended up being the module of choice even though I'll probably never use those functions, I wanted to know how to set it up, so I gathered the parts from a local Pick it yard and got busy.
More study and time spent thinking over the possible ways of doing it and I was ready to tear into it, so I took all this stuff out.
No more ballast resistor, or ECU or factory coil on my intake and inner fender.:cheers:
These are the replacements.
HEI E-coil, 8 pin HEI ECU and heatsink.
And a rotor with a .060 longer contact to keep arch burning down inside the distributor. (not shown)
The spade connector that is not connected is the tach lead.
The plug on the ECU without a connector in it is the port that the controller (guage) I mentioned above plugs into that gives all those added functions of settable base, total and advance curve from inside the vehicle with a lit readout of the settings that are saved to it.
I bolted the new E-coil at the same bolt location that the VR used, and mounted the new 8 pin module and heatsink over the ugly hole where the ballast used to be.
Removing the original coil, wiring, and bracket made it a lot easier to get at the distributor when needed.
Last step of the install was to change gap on the plugs to .045
The car fired right up, but I could tell something was off and I had to set the idle mixture screws a little leaner (1/4 turn) to get it back nice and smooth again. (apparently it didn't need as much fuel with a hotter larger spark?)
I also noticed on the test drives that the car seemed to react and respond better to everything from idle to WOT and seemed to require less throttle to move the car. (maybe my imagination, who knows) but that is the way it seems.
(I know a few people that will be real interested in this part.)
Not once today did the car pull it's hot start sputter sputter crap like some of the other Eddie carbed cars out there.
Have to wait and see if that problem is gone, as it's too early to know for sure.
I think I'm in love as it seems to have changed a few little things for the better and it's just that much more fun to drive now.
All said and done, I'm REALLY happy with it and surprised that it made as much difference as it did.
Looking forward to a gas mileage chk now.
This is the unit I may settle on to build and sell as a kit.
Thanks for the heads up on the VR guys, it's fixed now.
I also finished pulling the ECU.
A few weeks ago I decided I was going to end up with a high energy ignition system in my 73 Dart.
Took me a few weeks of planning in my time off here and there, and lots of investigation of schematics for different coil models and designs.
At first I was going to use the four pin module like most people that have done it, but an 8 pin module was suggested by (sorry, don't remember) but it was a fellow FABO member.
That got my curiosity up, so I chked into the 8 pin modules and what made them different or better than the four pins.
Come to find out that they are not really different aside from the computer controlable chip in them that allows the module to change the ignition timing when the engine needs it to adjust for elevation, change fuel mixtures and RPM changes, as well as engine load changes and the ability to hear and preignition knock and adjust the timing to correct it. (Some EFI packages such as the Mega Squirt use an 8 pin HEI module to help manage the fuel system)
Well, my car will never have a Mega Squirt EFI system so I don't really need the 8 pin module for a mostly stock 73 carbed 318 and the four pin would have been just fine.
Normally the computer in a newer car or truck controls the 8 pin module to handle the varying needs of the engine for ignition timing, but we dont have that computer in our old Mopars so what is the point of having the 8 pin module when the four would do the same job? Right?
I decided on the 8 pin so I would know how to set it up mostly because of this little peice of inginuity, http://www.rabidgator.com
Thier website is not functional yet, but the pdf document that desribes the product can be gotten here. [ame]http://www.letsgocomputers.com/docs/timingcomputer.pdf[/ame]
If you need Adobe's Acrobat Reader to view this document, it can be downloaded free here. http://www.adobe.com
This product looks like it would an invaluable addition to the HEI system.
It Looks like most any other guage, but these are some of it's fuctions.
1. Can set base timing, max timing, and even the advance curve all from the guage on the dash.
2. Has built in rev limiter as well as a shift light with user definable settings.
3. Has the ability to automatically retard the ignition when using boost, by sensing manifold vacuum and pressure.
It is able to do this only through the 8 pin module via the extra for pins that control timing.
This is why the 8 pin ended up being the module of choice even though I'll probably never use those functions, I wanted to know how to set it up, so I gathered the parts from a local Pick it yard and got busy.
More study and time spent thinking over the possible ways of doing it and I was ready to tear into it, so I took all this stuff out.
No more ballast resistor, or ECU or factory coil on my intake and inner fender.:cheers:
These are the replacements.
HEI E-coil, 8 pin HEI ECU and heatsink.
And a rotor with a .060 longer contact to keep arch burning down inside the distributor. (not shown)
The spade connector that is not connected is the tach lead.
The plug on the ECU without a connector in it is the port that the controller (guage) I mentioned above plugs into that gives all those added functions of settable base, total and advance curve from inside the vehicle with a lit readout of the settings that are saved to it.
I bolted the new E-coil at the same bolt location that the VR used, and mounted the new 8 pin module and heatsink over the ugly hole where the ballast used to be.
Removing the original coil, wiring, and bracket made it a lot easier to get at the distributor when needed.
Last step of the install was to change gap on the plugs to .045
The car fired right up, but I could tell something was off and I had to set the idle mixture screws a little leaner (1/4 turn) to get it back nice and smooth again. (apparently it didn't need as much fuel with a hotter larger spark?)
I also noticed on the test drives that the car seemed to react and respond better to everything from idle to WOT and seemed to require less throttle to move the car. (maybe my imagination, who knows) but that is the way it seems.
(I know a few people that will be real interested in this part.)
Not once today did the car pull it's hot start sputter sputter crap like some of the other Eddie carbed cars out there.
Have to wait and see if that problem is gone, as it's too early to know for sure.
I think I'm in love as it seems to have changed a few little things for the better and it's just that much more fun to drive now.
All said and done, I'm REALLY happy with it and surprised that it made as much difference as it did.
Looking forward to a gas mileage chk now.
This is the unit I may settle on to build and sell as a kit.
Thanks for the heads up on the VR guys, it's fixed now.
I also finished pulling the ECU.
