GM 4 pin HEI to 8 Pin Hei conversion possible

lani16 · Post by **lani16** » Thu May 25, 2006 6:03 pm

Hello everyone i guess i'm the newest member of the magasquirt comunity so here we go: I'm using MS-II 2.6/V3 Main Board. My proyect is a 427ci SBC I'm usinga MSD Por Billet HEI Coil in Cap distribuitor with mechanical/vacum advance and as far as i know it has a 4 pin module on it. Is it possible to put a 7 or 8 pin module on itso i can control my timing with MS II or any way i can control timing using this distribuitor i know i have to lock out the vac/mec advance mechanism on it but i don't know if i can just trow a 7 pin module on it and call it good. the point is to try to salvage my distribuitor is imperative that i have full control over my timing cuz because i'm going to the dark side with two hair dryers thanx a lot for any help

MegaScott · Post by **MegaScott** » Thu May 25, 2006 6:22 pm

lani16,

Welcome to Megasquirt.

Yes, going to the "Dark Side" can be very formidable, and require you to use Megasquirt for spark control.

Take a look at the Megamanual, there are basic instructions for the 7pin (or 8pin) module MS2 and hookup to a stock distributer, which is very similar to the MSD dizzy.

http://www.megamanual.com/v22manual/mtabcon.htm

There is MS2 specific info in there Click on "GM HEI"

Cheers!!, and Good luck.

Bernard Fife · Post by **Bernard Fife** » Thu May 25, 2006 6:30 pm

lani16,

In addition to Scott's advice, a few notes:

- the 4 pin, 8-pin and 7-pin modules have slightly different mounting patterns, which would require some drilling and tapping in your distributor,

- the 8-pin module isn't the best choice for a 4-pin distributor, it has a completely different case design that is partially inside and partially outside the distributor cap,

- the 7-pin module is the closest fit for the 4-pin distributor. The VR sensor plug fits, but may have to be turned upside down (some 4-pin distributors use the oppposite VR sense compared to 7-pin modules),

- you can use small female spade connectors for the 7-pin module (rather than the specialized connectors in the 8-pin module).

Lance.

lani16 · Post by **lani16** » Thu May 25, 2006 6:55 pm

So you're telling me that i can just swap modules and be able to control my spark with MS II. Mounting the module is no problem i don't care if it goes outside of the distribuitor. and how would the wiring go if any of you know and any other mods that i might have to make thanx

rs2000 · Post by **rs2000** » Thu May 25, 2006 7:10 pm

Wouldn't it be simpler to use direct coil control with the VB921 and no module? Or is the 7/8 pin more robust?

andrew

lani16 · Post by **lani16** » Thu May 25, 2006 7:15 pm

would i be able to control timing with direct coil control and can i control the coil on the HEI like that. and how would the wiring in the dist go?

lani16 · Post by **lani16** » Thu May 25, 2006 7:26 pm

i was doing some research and foun this http://www.mez.co.uk/ms9.html from eliot i don't know if that's what i need to do but i can't get much out of that page like if the vr is added on or is just the magnetic pickup like the one i have already?any info on this?

Bernard Fife · Post by **Bernard Fife** » Thu May 25, 2006 7:38 pm

lani16,

See this: http://www.megamanual.com/ms2/GM_7pinHEI.htm

Lance.

lani16 · Post by **lani16** » Thu May 25, 2006 7:41 pm

i sein that manual about the GM HEI modules but my question is how if possible to convert my 4 pin distribuitor to a 7 pin so i can control timing cuz with the 4 pin u can't according to that page

Bernard Fife · Post by **Bernard Fife** » Thu May 25, 2006 8:12 pm

lani16,

You need to:

- lock the advance mechanisms (mechanical and vacuum) in your distributor,

- remove the 4-pin module,

- fit the 7-pin module by drilling new mounting holes,

- hook up the 7-pin module as shown here: http://www.megamanual.com/ms2/GM_7pinHEI.htm

Or buy a 7-pin distributor from eBay, etc.

Lance.