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| MSD wiring question. https://slantsix.org/forum/viewtopic.php?t=47363 |
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| Author: | Sam Powell [ Sat Dec 24, 2011 5:18 am ] |
| Post subject: | MSD wiring question. |
Hi Guys, I wish to get the MSD ignition back in the picture with the current HEI module. I found diagrams for wiring an MSD ignition into a GM HEI 7 pin set up, but they show using the stock GM coil and harness. Since I am using the Blaster coil, I wish to know the more basic theory behind wiring this in. Can you tell me where to go for this info please? Does one of the wires between the ECU and HEI hook up to the white MSD. One of these wires is the signal from the HEI to the ECU and one is the timing bypass,(which is pretty obvious with its disconnect). The other must be the timing signal back from the ECU to the HEI. Will this fire the MSD box via the white MSD wire. Or does one of the wires going to the coil from the HEI trigger the MSD box. I assume the coil wires from MSD hook up to the coil as before? Thanks. Happy Holidays! Sam |
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| Author: | Rick Covalt [ Sat Dec 24, 2011 5:46 am ] |
| Post subject: | ?? |
Hey Sam, What is the purpose of running 2 ignition modules? Rick |
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| Author: | Sam Powell [ Sat Dec 24, 2011 7:00 am ] |
| Post subject: | |
The HEI converts the VR signal to square wave, and sends it to the ECU. The MSD is then triggered by the ECU to provide the spark for the hotter coil. This may seem convoluted, but this will allow me to put the MSD box in without reconfiguring the ECU wiring. If this improves things, I can rewire the ECU later. Sam |
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| Author: | Sam Powell [ Sun Dec 25, 2011 5:04 am ] |
| Post subject: | |
I got the answer from Peter. The white wire on the MSD is fired by contact C frpm the HEI. The coil is fired by the MSD as per normal MSD set up. The HEI must have a direct switched 12 vol to pin X, since this HEI set up gets its 12 volt feed from the coil harness, which I will replace with the Blaster coil. Merry Christmas to all. |
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