MSD questions

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Longgone

Longgone

John/68 Barracuda & Dart
Joined
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Can somebody answer a couple questions for me about the MSD 6al? Is it necessary to drill holes in the distributor cap? If so ,where do you drill them and how large should they be? Can the ballast resistor be removed? What plug gap works best for street use with 10.5-1 compression? Thanks!
 
I never drilled the vent hole in the cap. Lots of replacement caps are vented at the top anyways.

No need for the ballast resistor, I remove the resistor from the back and solder a piece a wire in it to by pass it so it looks stock.

I usually run a 45 to 50 gap.
 
I'm going to run a Mallory box and the pricipals are pretty much the same. Drilling the hole in the cap is only to release the electically charged air from underneath the cap. I believe this is only necessary if your cap does not already have a vent. My cap does, so I'm not going to worry about it. According to the instructions that came with my box, you can remove the ballast resistor (correct me if I'm wrong here guys). As far as the gap Mallory recommended starting at the stock gap and adjusting it according to trial and error. But, I'm sure somebody on here has had enough experience with these systems that they have a gap figured out that works best.
 
I also have not drilled the cap, and I don't use the ballast resistor.
As for the gap, I am running a .045" like Adam. I figure with the better coil and the multiple spark .045" was a good place to start.
 
In a stock ignition the ballast is limiting current flow to the coil. When you install a capacitive discharge ignition like and MSD this wiring is no longer hooked to the coil. MSD's suggested installation instructions have you hooking this wire to wire that turns the unit on and off. This is a low power circuit and having the ballast resistor in the circuit does not impact the function, that's why they don't tell you to remove it. Since the ballast no longer serves a purpose and by leaving it in you create another potential point of failure I would jumper it out.
 
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