MSD wiring

thebigslide

Registered User
Does anyone have a wiring diagram for the 8981 timing computer? Or the MSD wiring book? I've lost my diagram somewhere and I don't know what to do.

I have 6 wires on this bad-boy: red, black, yellow, grey, white and violet.

I'm assuming the red and black are power (constant on)

No idea how to wire up the other four and I worry that if I do it wrong, I'll blow something up (like the computer).

Help!

Edit: Just to clarify, 2 of the remaining wires go to the ignition controller and the other 2 come from the pickup on the distributor.
 
Go to this webpage and click on Downloads. There are install instructions there for just about everything MSD sells. The instructions for the timer will be listed as part of the ignition box instructions.

http://www.msdignition.com/

What ignition box are you using it with ?

David
 
David Neibert said:
Go to this webpage and click on Downloads. There are install instructions there for just about everything MSD sells. The instructions for the timer will be listed as part of the ignition box instructions.

http://www.msdignition.com/

What ignition box are you using it with ?

David
David, I'm using it with a 6AL
MSD doesn't list the wiring diagram for the 8981 anymore. But I figured it out. White goes to ignition output, yellow to the MSD input, Grey and yellow are shorted for a high speed retard (using plugin chips and/or a window switch).

Here's what I'm using it for. I have a TFI distributor in my carb'd 302. The SEFI distributors use a hall effect pickup that uses a windowed iron rotor to trigger the sensor. The stock sensor has the #1 cylinder timed 10 degrees advanced over the other cylinders. (actually #1 is 28 degrees advanced and everything else is 18 degrees advanced) That's so that the EEC knows when #1 is firing so it fired the injectors in time with the firing order. (for anyone not familiar with

What I've done is ground down the wheel so that all the cylinders are 28 degrees advanced and then retarded the distributor 30 degrees. This gives me a very accurate (to 9400RPM so far) very consistent (no moving parts) magnetic pickup for about $15 from the wrecker. You have to stick the trigger wheel in a furnace to anneal it after you grind it as it will be slightly magnetized afterwards (good practice anyways).

The MSD timing computer is really nice; I have to wonder why they're discontinued. It allows setting the base timing by turning a screw on the control box. Then you can set the slope and initial RPM for the 'mechanical' advance. You have to use it with a spark amplifier. The one on the TFI distributor should work if you don't have an MSD ignition.

The only downside to this situation is that there's no vaccuum advance on the distributor. I'm working on a way to modify the base of the TFI distributor to accept a vaccuum advance where the octane rod used to go, but till then, I'll have to eat the 4MPG I've lost. Oh well, I picked up about 15HP over the crappy points distributor I was using before (by the butt method) :)
 
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