[Diy_efi] GM HEI Coil

[Torbjörn Forsman]

Milosz Kardasinski wrote:

>Does anyone know the pinout of GM's External HEI coil. I talking about
>the one that is used with the small cap HEI distributors, that is
>mounted to the intake.
>
>There are two harness connectors on it with total of four leads.
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>
>  
>
This sort of ignition coil can have many different types of connectors. 
The most common, at least on european GM cars, is that it has four 6,35 
mm blade connectors in two groups. Each group of blade connectors is 
connected to one end of the primary winding, i. e. there is two blade 
connectors for each end.  A very small + sign is molded into the plastic 
near one of the connector groups.
There may also be a connector with three 4,8 mm blades, in this case two 
of them is + and the third - . Also in this case, the + is indicated 
near the connector.
If in doubt, it is easy to measure the resistance between the pins to 
see which ones are interconnected. Typically the primary winding has 
about 0,4 ohms, it is difficult to measure such small resistances with a 
cheap multimeter so it may be better to introduce some amps of current 
(12 V dc in series with a 21 W bulb for example)  and measure the 
voltage drop.

/Torbj?rn Forsman