MS2 - HEI7pin - MSD 6AL observation

krisr · Post by **krisr** » Mon Nov 07, 2005 4:41 pm

Hey guys,

Not a question/complain/whinge/query or anything, but a mere observation some might be curious to know. I've got my MS2 running ignition only for the time being. The carb mule is a 625 Carter AFB. Camshaft is 245 @ 0.050 in a 400 cube motor.

Out of curiosity, I decided to put my spare MSD 6AL box inline to drive the coil. I had recently changed coils to an e-core style coil rated at 75:1 turns and peak current of 300mA. Anyhow, my idle AFR's are about 13-14:1 due to cam size. After doing NOTHING else except for wiring the MSD unit on the coil, still being triggered by the HEI 7pin unit, I noticed my idle AFR's lean out to about 15-16:1 !!! with a higher idle speed (probably from a more efficient burn).

Tell me it's too good to be true!? Has anyone else done any experiments like this lately?

Kris

TimMoman · Post by **TimMoman** » Wed Nov 23, 2005 7:46 am

Yep, engines always run better when the fire is lit

I have experienced similar with cammed motors. Usually the larger the cam, the more the affect. The MSD will usually drive the coils much better than the HEI module.

ChevelleFan · Post by **ChevelleFan** » Wed Nov 23, 2005 8:57 am

How exactly do you have your ignition setup? I'm running MS-II in fuel-only mode and plan on switching to an 8-pin HEI this winter, but I'd like to keep my MSD 6AL in the system.

Do you have the ignition control wire from MS (pin #36?) hooking to the white MSD wire?

-Dave

krisr · Post by **krisr** » Mon Dec 19, 2005 7:38 pm

I had setup the "C" pin (coil) to goto the white wire on the MSD 6AL from the HEI module. At the moment i'm back experimenting with the VB921 driver to send the logic signal to the MSD (white wire).

I have managed to get the car running with the VB921, except I have a feeling I have my input capture around the wrong way. It is a MSD Probillet distributor and the IIC is setup for rising edge. From what i've seen through the archives is that VR sensors typically like falling edge capture. Basically I could get the car to idle with the proper amount of timing as entered into the ign map, but when driving the car has a nasty miss and pops out the exhaust so it's firing to late.

I ran out of daylight last night, that and the car is VERY noisy to fire up in the middle of the night so hopefully after work i'll be able to do a bit more testing.

Dave: In answer to your question yes. The white wire should goto Pin36 (S5 - RelayBoard). But you'd need the VB921 for this.

ChevelleFan · Post by **ChevelleFan** » Mon Dec 19, 2005 8:47 pm

Krisr, thanks for the update. Keep posting with what you find works best. I am interested in hearing your result, as I'm sure others will be too.

-Dave