Topic: ignition..need help
in Forum: C3 Electrical
I just installed a complete MSD System, Pro-billet tach drive distributor, 6AL box, blaster 2 coil, new super conductor 8.5 wires, new plugs. I used the R44TX ac delco. I am having a miss/hesitation on accelleration and it runs like crap at the top end. I have the bushing that allows for a total of 25 degrees of centrifical advance and the spring set up that allows full advance around 3500-4000 rpm. My idle is a little rough, but it starts ok. My initial advance is 12 degrees. What am I doing wrong? Also, can I install an adjustable vacume advance on this distributor?
Help please, anyone...
Your 68 has resistor wire that runs to the positive side of the coil. If your using this wire to supply voltage to the red 12volt switched wire on the ignition box then you will only have roughly 9 volts which is not enough to run an MSD system.
Their instructions are pretty clear about this. To by pass the resistor wire you must find the wire at the firewall where it enters the fuse panel and run a non resistor wire up to the box to get a full 12 volts. The other option is to run a 12volt wire off the bat terminal on the altenator to the 12v switch wire on the box. However you decide to do this the wire must have 12v before and after cranking.

marked Batt, Acc, IGN, I made sure they were switched on and off by the key switch, took a volt meter and checked for 12 volts when on and during cranking, when cranking volts will drop a little not much, its been a while and I can't remember if it was Batt or Ign,
ANYway I piggy backed off the the spade to a circuit breaker with a 12 ga. wire, out of the breaker with 12 ga to a hidden disconnect switch, out of the disconnect with 12 ga wire, through the firewall grommet, to the HEI, you can do the same with the MSD box with or without the disconnect switch I believe.