Thread: MSD Success
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PrimeMvr PrimeMvr is offline
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Join Date: Dec 2010
Location: Iowa
Posts: 370
MSD Success

First a little history that might help another newbie troubleshoot...

Since winter hibernation, I've been chasing issues with my 87 930. It wouldn't idle when cold, the throttle response below 2k was seriously pathetic, and there was an inconsistent hesitation at various RPMs on WOT.

Vacuum leaks-check. AAR-check. Fuel pressures-check. Injectors-check. Then a round of "what if I buy this..." LM-1..AFRs-check. Plugs/wire/cap/ improvement. Clean and grease every fuse and connector I can improvement.

Trolling the forums, it dawned on me to check the timing. Dumb to have overlooked it, but it's been a long time since I owned a car that has a dizzy. The idle timing was actually retarded 5* and didn't change with the lines on or off. Hmmm.

I pulled the dizzy and discovered the vacuum retard side of the pot was leaking (didn't discover that with my ether tests) and the whole mechanism was "creaky" and tight. Rather than replace it, I decided to delete the whole pot, lock the dizzy and get a 6AL-2 programmable MSD unit to handle the timing.

I installed the 6AL-2 with a 3 bar MAP and Blaster 3 high vibration coil. I switched to NGK R5671A-8 plugs gapped to .040 and a Napa EP407 rotor. I set the timing at 26* and then set the MSD to retard off 16* at idle and gradually let it back in by 2k. The boost retard is set to back off 12* by .5 bar.

Amazingly it started on the first crank and hit a nice high idle. I haven't done a respectable full blast run yet, but the throttle response is night and day from before and it is so much smoother through the midrange. I am sure there are some gains yet with more agressive mapping of the advance, but I want to spend more time with it first. All in all, very happy at the moment.

The unit and MAP both fit nicely where the old CDI was (for sale soon once I'm sure all is good for awhile).

I locked the stator (is that the right name?) by tapping in a screw with a dab of Loctite. I removed the weights, shimed up the mechanism so when the spindle screw under the felt is tightened, it actually locks the spindle from turning. I chose to lock the dizzy in full advance as a safeguard, if something comes loose it will go to retard instead of advancing.

Hope someone finds this helpful, it was a fun project.

87 930 - Black - 3.4L/964 cams/K29/Powerhaus IC/6AL-2/B&B dual exhaust/MTX-L/235-315 Toyo R888/18" Kinesis wheels/Big Red brakes/LSD
10 997.2 Cab - Speed Yellow
83 SC Cab - Guards Red [SOLD]
17 NSX - Nouvelle Blue
Old 05-24-2011, 10:21 PM
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