Msd problem

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Steve silver

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Marion nc
Got a strange one. 451 stroker normally aspirated. Msd 6al ignition. No spark from coil. If I take the distributor out of engine and manually turn spark. Has magnetic pickup. Reinstall distributor and no spark. Took distributor out and manually turn again, spark. Reinstall no spark. Blowing my mind.
 
Also make sure the cap button is touching the rotor. What coil are you running. We have had some issues with the high vibration coils failing. Check the instructions in the box for how to test the coil. Ohms check the coil wire.
 
Check pickup for continuity TO GROUND. It should be "open" IE infinity. Also did you check that the distributor is actually turning in the engine? How good is the battery? Is it fully charged? Spins the engine good? Then while cranking, measure voltage between "big red" and "big black" What is that voltage. Then measure again from the small red trigger wire to ground. Must have battery voltage there while cranking and while running
 
MSD Problem > here is the cure.

Screenshot_20210901-024240_Gallery.jpg



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67Dart273 said:
Check pickup for continuity TO GROUND. It should be "open" IE infinity. Also did you check that the distributor is actually turning in the engine? How good is the battery? Is it fully charged? Spins the engine good? Then while cranking, measure voltage between "big red" and "big black" What is that voltage. Then measure again from the small red trigger wire to ground. Must have battery voltage there while cranking and while running
Click to expand...
i am thinking DIST not grounded.....
 
The guys above solved it. Something is getting grounded that shouldn't be, when the distributor is in the block. Take it out, ground goes away, you get spark.
 
Is the 'in the block' testing being done by cranking the engine? If so, there will be a substantial voltage drop throughout the electrical system during cranking. If the MSD box is getting insufficient voltage during cranking, then no spark. Make sure the 6AL is wired correctly.
 
OK The pick up is not grounded however the HEI module has to be you cannot trust the dist clamp to do it alone.
 
Bewy said:
Is the 'in the block' testing being done by cranking the engine? If so, there will be a substantial voltage drop throughout the electrical system during cranking. If the MSD box is getting insufficient voltage during cranking, then no spark. Make sure the 6AL is wired correctly.
Click to expand...
Thought about this. Checked with distributor out and spinning manually while turning engine over. Sparked as it should
 
Scody21 said:
Also make sure the cap button is touching the rotor. What coil are you running. We have had some issues with the high vibration coils failing. Check the instructions in the box for how to test the coil. Ohms check the coil wire.
Click to expand...
Coil checks good. Actually tried another. The crazy thing is it fires when the distributor is not installed but will not fire when installed
 
67Dart273 said:
Check pickup for continuity TO GROUND. It should be "open" IE infinity. Also did you check that the distributor is actually turning in the engine? How good is the battery? Is it fully charged? Spins the engine good? Then while cranking, measure voltage between "big red" and "big black" What is that voltage. Then measure again from the small red trigger wire to ground. Must have battery voltage there while cranking and while running
Click to expand...
Thought about the voltage thing. When distributor un installed it will fire while turning engine over
 
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