Re: TR - HEI wiring scematic
I'm suffering through a host server that after all this time, the tech guys say the server is too slow...
I couldn't tell you, I'm completely host literate.
They have been promising 'Two weeks...' for five months...
One problem, we got hacked two days after we got the T-1 line, and the Chinese hackers really did a number on the system.
We've had to pretty much start from scratch again.
As for the HEI...
Not my first choice, but here is the run down, please find your year vehicle...
If you are switching from a Motorcraft ignition ('78 to '90)
I think you are doing your self a disservice.
With just tune up parts you can kick the GM HEI's butt with the Motorcraft ignition, and not change anything but cap, rotor, wires and coil.
The feed wire in the '78 to '90 service is not large enough unless you strip back to the 10 Ga. fee wire.
You will start at the DuraSpark module Red wire, and strip back to the splice where it connects to a 10 Ga. wire.
Connect that 10 Ga. wire to your GM HEI, and your ignition should work pretty well to about 3,500 RPM, tach should work.
Behind this splice will give you a 10 Ga. source with no resistor in line.
Leave the other wires in the splice, and tape over the factory coil connections.
You will have to run a 10 Ga. wire from the 'I' terminal of the starter solenoid to the feed for the HEI (where you attach the connector for the HEI to the Splice is fine).
Disconnect the wire that is factory attached to the 'I' terminal, it's no longer needed.
(All stock GM HEI distributors become unstable around 3,500 RPM (or below), but a custom module and a remote coil will help with that)
I have nothing against the HEI for an upgrade from Prestolite. ('74 to '77)
I'd use a relay for the power wire, but if you strip the Prestolite module White wire back to the three way splice, and start from that wire, you should be fine, and your tach will work also.
If you have Delco points, ('73 & older) you will need to find the positive feed wire to the coil.
You will have to use a relay to feed the GM HEI.
If you have this points system, post back and I'll give you a diagram.
I assume you are installing in a 258 CID I-6.
If so, you might want to look into using the distributor cap and remote coil from a '76 Chevy 250 CID I-6.
Moving the coil from the cap is a BIG plus, and with the stock Chevy parts, it's only a two wire connector and a coil wire away.
Get it running and consider this later. It's just tune up parts, and it does make a difference.