Hi guys, I have a 1970 GS455 that I recently did a motor swap in. I pulled the original 455 and put in a rebuilt one I found on CL. I couldn't resist the price, and this will let me enjoy the car while I start the rebuild. Anyway, when I start the car, it acts like the coil isn't getting power during cranking. I can still start it by turning it over a bit, but it hardly ever fires up until the instant I release the key... then she sputters to life. The motor runs great once fired. The reason I mentioned the motor swap above is, I believe the car was doing the same thing with the original motor (albeit with more smoke and less oil pressure!) hehe. So, the issue has to be in the car, not the motor or HEI (I guess). Where should I start? Does it sound as basic as a bad ignition switch? Something with the way the starter solenoid is wired? Electrical short? Advice always welcome! Thank you!
So the engine in the car currently has HEI? With the original points set up, the harness has a resistance wire going to the external coil. It cut the voltage down in the "RUN" position to 5 volts so not to burn up the contact set. The HEI on the other hand needs a straight 12v wire going to it. The first thing I would check is to make sure you have 12 volts going to your HEI when the key is in the "RUN" position. Sounds like you may only have 12 volts in the "CRANK" position. Trace the wire back that feeds the distributor and find out where they got power from. In other words, where did they splice that wire into the harness?
There's a Yellow wire coming from the starter solenoid that supplies 12V in the crank position ONLY. This was to supply a full 12v to the ignition coil ONLY in the crank position for easier cold starts. I didn't hurt the points because it was for a very short duration of time. It was hooked to the coil + side along with the resistor wire. The reason there are TWO wires attached to the + side of the ignition coil. Almost willing to bet somewhere along the line the Yellow wire was taken out of the loop. I have run HEI's for yrs. with the resistor wire in place used to trigger a relay to supply 12 v to the HEI. NO re-wiring nec. Tom T.
Looks like I might of. Must of misread his post in my pre-morning coffee fog. Either way, he needs to check the wire powering his distributor in both crank and run and report back to us
Ok, so nothing really to report. I dropped the starter, checked the wires, and while in the process noticed the + wire to the coil was dry cracked. Taped it up and she fired like a Buick should. I guess that was all it was? It doesn’t really explain the symptoms... On the solenoid, I don’t know how to tell which wire is which. One of the wires has long since been rewrapped with electrical tape. I guess a new engine harness wouldn’t kill me. Just out of curiosity, what would happen if the R and S leads were switched on the solenoid? Wouldn’t the starter engage when the car key is in run?
If there's an open in the wire that you sort-of healed by taping it, it exactly explains the symptoms. The issue will be "how long does it last" because you haven't really FIXED the broken wire. The solenoid is marked "S" and "R". The original wire that would go to the "S" terminal is larger-gauge than the original wire that goes to the "R" terminal. "S" terminal wire is purple (often fades to pink-ish.) In "Run" the "S" terminal would be back-fed reduced voltage via the ballast resistor (resistor wire) and the wire that would normally go to the "R" terminal. There wouldn't be enough power to engage the starter solenoid, but it would reduce the power that should be going to the coil and points. The engine wouldn't crank and therefore couldn't run. Over time, it would kill the battery and heat the windings in the solenoid. If the points were closed, it'd heat the ignition coil, too. If the points were open, it wouldn't heat the coil. In "Crank", the purple wire would supply power to the "R" terminal, any power supplied by the purple wire would end at the R terminal because it doesn't make electrical contact until the solenoid engages.
