MSD 6A, HEI 7/8, & MSII

masterchopchop · Post by **masterchopchop** » Tue Dec 27, 2005 2:54 pm

I'm putting MSII, v2.2, on a 91 camaro with a 383. I have read posts by people using MSD 6A and it seems the prefered method of wiring with MSII is to hook the white wire from the MSD to the C pin on the HEI 7/8-pin module rather than using a 4-pin HEI setup as shown in the manual http://www.megasquirt.info/ms2/msd6a.htm. Is there pros/cons of one wiring method over the other? Also, can a HEI 7/8 be used in place of the HEI 4?

Teranfirbt · Post by **Teranfirbt** » Tue Dec 27, 2005 8:57 pm

I'd also like to know some info about this.. I'll be using an MSD 6A on my 22RE (well, I already am..)
I understand how to set it up with MSnS, but I don't plan on doing spark control at first.. Would I just be connecting the tach output to the MS to give it an RPM signal?

goodyearsmokesignals · Tue Dec 27, 2005 9:26 pm

Masterchopshop, are you planning on controlling spark with MS2 or just fuel?

Teranfirbt yes if all you want to do is control fuel for now using the tach signal from the MSD would be a good signal for the MS

masterchopchop · Post by **masterchopchop** » Tue Dec 27, 2005 9:53 pm

I am going to use the msII for spark. This is how I think I would could use the HEI 7/8 in place of the HEI 4. I haven't tried it yet so any feedback would be appreciated. It just doesn't look quite right...
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goodyearsmokesignals · Tue Dec 27, 2005 10:58 pm

yep that looks right to me, make sure you bring the spark output out on pin 30 from the ECU and it shud be gud.

masterchopchop · Post by **masterchopchop** » Wed Dec 28, 2005 1:22 am

Here's a link to the drawing if it doesn't appear here. http://www.geocities.com/masterchopchop ... _blue.html

masterchopchop · Post by **masterchopchop** » Wed Dec 28, 2005 9:14 am

I just found this diagram from another post of a 7pin hei. See it at http://photos.yahoo.com/masterchopchop Looks like the B-pin and the relay going to the B-pin aren't needed. I'll try it this weekend and update.

ChevelleFan · Post by **ChevelleFan** » Wed Dec 28, 2005 9:22 am

Your link is not publicly viewable. Something about you need to enable public albums to share.

-Dave

masterchopchop · Post by **masterchopchop** » Wed Dec 28, 2005 9:35 am

woops. fixed.

krisr · Post by **krisr** » Wed Dec 28, 2005 4:41 pm

A couple things, I'm doing this setup myself and have been experimenting for a while with my MS2 v3.0...

Initially I wanted to use the VR Input & VB921 to trigger the coil/MSD, but I could never get it to function right. I either had a wiring or settings problem. I thought I had tried every possible combination possible. Anyhoo I had given up as HEI7 had worked flawlessly before. My main aim was to keep a friendly wiring space under my dashboard, hence trying teh VB921. The VB921 would have no reason to fail as it would only be sending a logic signal, not actually driving a coil.

You could wire up MSD off the HEI7 as below (i've done it before and know it works).

P&N - Pickup coil
E - Pin 36 (JS10 - IGN)
R - Pin 24 (Hall input)
B - Relay method, or jumper JS11 to SPR3, set the Knock Enable pin in Megatune to turn on if RPM > 300 - I've tested this too and works.

C - Wire to MSD white wire (points/hall trigger for MSD)
B - Switch 12V & Small red wire on MSD also.

I don't have a v2.2 so I can't comment on the pin assignments on the DB37 but yeah, I have tried that and it works on a v3.0