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SBC Msd ignition issue


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Ok so I have a 1976 Datsun with a SBC in it. The ignition setup is a MSD Digital 6 Plus, MSD Blaster SS coil and MSD pro billet distributor. My issue is that I am getting spark to the cap but nothing is coming out, if i manually trigger the coil via jumping out the trigger wire while the rotor is pointing to cylinder one post the plug will fire but when I crank with everything connected I get nothing at any cylinders. I called msd and they told me the spark is grounding out inside the cap but i find that hard to believe. Have tried a new coil with no luck. When I put a plug directly to the coil wire it fires rapidly like it should so spark is going in but not coming out. Any ideas? or has this happen to anyone else? Thanks David

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Also...

 

1: Check the center button on the distributor cap. Make sure it has not eroded away.  Look for carbon tracking inside cap. Hairline :traces of carbon leading from plug terminals. Can look like hairline cracks. If you find either condition the cap is hooped. Replace it.

 

2: Check your rotor phasing. MSD has Tech articles on it. Can especially be a problem with a  locked out Dizzy ( Mechanical advance locked out ) and Dizzy's that are used with Ignition Boxes or ECU's that have programmable timing curves.

 

Just want to be clear on one point. If you pull the coil wire from the dizzy end, place it near the engien or chassis and crank engine over.... you get a good strong spark? Is that correct?

Edited by Chickenman
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Regarding the rotor. Pull it off and check the bottom side in the Center. If you find burn marks, carbon tracking, or a lot of rust particles... that is a sign that the spark energy is arcing through the rotor. Rotor is toast. replace it.

 

Common causes of rotor arc through or Cap center button erosion are:

 

1: Poor quality ignition leads or leads with too high of resistance. MSD spiral core leads are good. Taylor and Accel seem to be crappola. Check the resistance of each lead with a Ohm meter. One bad lead will eventually cause the rotor to burn through.

 

2: Do not run too big of a Spark gap. Yes an MSD can fire a .050" to .060" Spark gap. That also places a lot of strain on other components such as Caps, Rotors and HT Leads as the spark energy level rises to the plug " Arc over " point. Keep the spark gap below .045". .040" is a nice range on Normally Aspirated Chebies.

 

Turbo cars are another matter. Please advise if you car is Forced Induction.

Edited by Chickenman
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Cap and rotor are both new and no burn marks on old one. The only thing g a little bit rusty is the pickup. The car is n/a.

Regarding the rotor. Pull it off and check the bottom side in the Center. If you find burn marks, carbon tracking, or a lot of rust particles... that is a sign that the spark energy is arcing through the rotor. Rotor is toast. replace it.

 

Common causes of rotor arc through or Cap center button erosion are:

 

1: Poor quality ignition leads or leads with too high of resistance. MSD spiral core leads are good. Taylor and Accel seem to be crappola. Check the resistance of each lead with a Ohm meter. One bad lead will eventually cause the rotor to burn through.

 

2: Do not run too big of a Spark gap. Yes an MSD can fire a .050" to .060" Spark gap. That also places a lot of strain on other components such as Caps, Rotors and HT Leads as the spark energy level rises to the plug " Arc over " point. Keep the spark gap below .045". .040" is a nice range on Normally Aspirated Chebies.

 

Turbo cars are another matter. Please advise if you car is Forced Induction.

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You didn't answer this which we need to know.

Just want to be clear on one point. If you pull the coil wire from the dizzy end, place it near the engine or chassis and crank engine over.... you get a good strong spark? Is that correct?

 

 

You mentioned that you can get a spark from coil wire when manually grounding Trigger wire... but do you get a good strong spark from the coil wire when cranking the engine on the starter. Yes or no?

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