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Thread: MSD 6AL cutting out at 3,700 rpm

  1. #1

    Default MSD 6AL cutting out at 3,700 rpm

    I am running a 6AL box with blaster SS coil and MSD pro billet distributor on a big block (RB) Chrysler. In car for 5 years with coil being about 3 years old. Recently had car on chassis dyno and ignition dropped off at 3,700 rpm on all 4 pulls. HP and Torque lines were steadily increasing until 3,700 when they dropped momentarily and then picked back up again and were steady through end of pulls at 5,500. I can't be sure if this is new, or has been that way since I put the motor in 5 years ago. It's a street car and I rarely have the pedal to the floor in this RPM range. I did on the way home that day and did notice a momentary blip at that rpm. Motor is 10.5:1 comp, iron heads, new plugs, rotor and cap just before dyno pulls. I would suspect the coil or a ground problem except that it happened at the exact same RPM on each pull. Would appreciate any advice from anyone having had a solved a similar problem. Thank you in advance.

  2. #2


    What we would look at like you said would be the ground, since if it was the box when something shorts in it, it would just quit, and as for the coil if it was in it, it would be more erratic and not just at the same RPM and just in one spot it would of started at the rpm and kept going till you stopped. So, where is the ground for your MSD box? Also, one other thing to look at would be if your heads and motor do not have a good ground, we would like to make sure if you have aluminum heads that both heads have a ground strap on them. And, to make sure the block has a good ground on it to the frame.

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