HEI ignition module

[stacey_65]

Hey guys, I have a 85 c10 with the H vin and a 305. I am building a 350 and purchased a billet HEI distributor. The billet distributor has a 4 pin module and the stock HEI has a 7 pin Module. Can I rewire so the 4 pin will work? What is the major difference in them? any help would be great Thanks.

[ray_mcavoy]

The 7-pin modules are used in applications where the ignition timing is controlled by an ECM. The distributors that use the 7-pin modules do not have any mechanical or vacuum advance mechanisms.

The 4-pin modules are used in distributors that do have mechanical (and usually vacuum) advance. The power feed wire (typically a 12ga pink wire) that plugs into the connector on the cap is the same and can be used to power the replacement distributor. Any remaining connectors (except for maybe a tachometer connection) that used to plug into the old distributor will be unused. And you can probably eliminate whatever ECM and wiring was associated with the old distributor.

[stacey_65]

Thanks for the info.