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By 62bigwindow - 9 Years Ago
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Has anyone had any experience with the MSD y block dizzys? I'm getting weak and sporadic fire at the plugs. My car sounds like it's only hitting on four cylinders. It's puzzling as last weekend we had it running and it sounded good but had to have a battery charger hooked up. As soon as it was removed it would start misfiring again. I thought I had a flooding problem because it smelled very rich but I now think it just wasn't burning all the fuel. When I put everything together I put all the wires to coil exactly back the way it was with the 6 cyl. Should I have ran a new wire to coil to produce a full 12 volts? If so where on the car can this wire run from?
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By Ted - 9 Years Ago
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The MSD three wire distributors (Ready to Run series) requires a full 12 volts to the red wire. Hooking that up to a resisted voltage source will damage the electronics after a given amount of time. Make sure the engine is well grounded to the frame if using an engine ground for the distributor.
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By Ted - 9 Years Ago
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Here’s the MSD wiring diagram for the 8383 Y-Block distributor.
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By 57RancheroJim - 9 Years Ago
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If you still have the original ballast resister on the wiring going to the coil it needs to be removed..
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By 62bigwindow - 9 Years Ago
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Thanks Ted. I checked all the grounds. I have a ground from the firewall to the engine,engine to the frame,and battery ground to the block. The dizzy ground is on the block behind the intake. I think I'll try to find a keyed 12 volt source on the car and run it to the coil like the diagram. Is there a source on a 56 car that will supply 12 full volts at all times? I assume there is one on the fuse box? I'm no electrical guru by any stretch so I'll need a little help on this.
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By ian57tbird - 9 Years Ago
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Your standard ignition wire should be fine on a 56 as the resister was not part of the wiring back then but a separate unit. To test, disconnect wires to distributor and ground your coil on the negative side. With the positive still connected to you ignition put a voltmeter on the positive of your coil and to a good ground. Turn on your ignition and you should get 12 volts. If you disconnect the ground wire on the coil then the voltage should rise slightly, maybe 1/2 volt, that is showing you the volt drop in you wiring and ignition switch (there will always be some). You need to have the coil grounded like I mentioned to give a load to get true voltage reading.
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By 62bigwindow - 9 Years Ago
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Thanks for the help. My plan is to remove the ballast resistory and run a new wire from the "i" terminal on the solenoid to the "+" side of the coil. Is this a constant 12 volt source? I couldn't really find to much info about the subject.
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By Ted - 9 Years Ago
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62bigwindow (5/1/2016)
Thanks for the help. My plan is to remove the ballast resistory and run a new wire from the "i" terminal on the solenoid to the "+" side of the coil. Is this a constant 12 volt source? I couldn't really find to much info about the subject.
If memory serves me correctly, the 12 volts off of the “I” terminal at the solenoid is only active in the key start position. You’ll need the 12 volt source that comes off of the ignition switch that originally went to the resistor that was mounted on the intake. Someone else feel free to correct me on this if I’m wrong.
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By 57RancheroJim - 9 Years Ago
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Ted is correct, the "I" terminal provides 12v to the coil when the key is in the start position. When the key is returned to the run position the power goes from the ignition switch to the coil. A ballast resistor is in line on that wire. You can remove that resistor and connect the two wires that are attached to it together to eliminate it, easier then running a new wire.
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By 62bigwindow - 9 Years Ago
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Thanks guys. Someone recommended the I terminal. While I have your attention I'd like to bend you ear one more time. Where is a good spot to hook up an electric choke?
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By 57RancheroJim - 9 Years Ago
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The I terminal is only energized when the starter is cranking.. I have the electric choke on my Holley connected to the + terminal on the coil.
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By oldcarmark - 9 Years Ago
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I wired mine from the Ignition Switch Terminal which is active when the Engine is running. Ad an Inline Fuse Holder to avoid a Fire in case of choke Malfunction. You must use a switched source otherwise the coil in the Choke will never cool and activate as it is supposed to.
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By DryLakesRacer - 9 Years Ago
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The use of the"I" terminal is what called the "hot start" so 12volts goes to the ignition during startup and drops to 9+ back on the ignition switch going thru the ballast resister. GM's use a 4th wire on their solenoid and a small brass clip that hits the copper disc when their solenoid is energized.
I would only use the positive wire on the coil for the electric choke if your system is not using the ballast resistor. If using the resistor use the lead wire from the ignition. I definately agree with a fuse in the el choke wire. Good luck.
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By Ted - 9 Years Ago
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62bigwindow (5/2/2016)
...While I have your attention I'd like to bend you ear one more time. Where is a good spot to hook up an electric choke?
If running the MSD distributor, then I’ll suggest hooking the electric choke to a 12 volt source that’s closer to the battery or ignition switch. Hooking the electric choke to the positive side of the coil will have the voltage to the MSD distributor resisted down and that is not desirable.
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By 62bigwindow - 9 Years Ago
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Should I find a new source of power for the overdrive then? The power wire for it runs off the + side of the coil also.
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By 57RancheroJim - 9 Years Ago
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62bigwindow (5/2/2016)
Should I find a new source of power for the overdrive then? The power wire for it runs off the + side of the coil also. I don't think you can change that. The overdrive shifting works by momentarily shorting the coil so the engine RPM drops momentarily.
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By petew - 9 Years Ago
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The only overdrive related wire at the coil should come from the kick down switch, and that is to interrupt (shut off) the motor so the trans can come out of OD when the kick down is activated . Power for the overdrive relay should come from the ignition switch.
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By 57RancheroJim - 9 Years Ago
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Ted (5/2/2016)
62bigwindow (5/2/2016)
...While I have your attention I'd like to bend you ear one more time. Where is a good spot to hook up an electric choke?If running the MSD distributor, then I’ll suggest hooking the electric choke to a 12 volt source that’s closer to the battery or ignition switch. Hooking the electric choke to the positive side of the coil will have the voltage to the MSD distributor resisted down and that is not desirable. Sorry didn't realize it would effect the MSD, my bad. I have a Pertronix II and it doesn't effect it.
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By 62bigwindow - 9 Years Ago
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Thanks to everyone for all the help. Got my wagon running tonight and it runs great. Got some fine tuning to do on the carb but,after 9 months of spending all my free time on it, getting to drive it was great!
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