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04-09-2009, 04:47 PM #1
OT(kinda) 350 chevy ignition wiring diag?
I was wondering if anyone had a basic ignition wiring diagram for a mid 80's 350 chevy motor w/HEI?
I have a old truck project and it died on me. Think the PO had the ignition wired wrong but I don't have enough knowledge myself to be sure. All I need first is to get it to start and stop. Replaced plugs, wires, cap, coil, etc but I don't think I am getting power to the. I really need to just start form zero and go through it. Any help is greatly appreciated!
I actually have been searching for this but it seems like most any question I have ever had (scramblers or not)- the knowledge base on here either has already covered it or knows the answer. Since I end up back here anyway I thought I woud ask ...
04-09-2009, 07:02 PM #2
All that a large-cap HEI needs to run is a power source. The connector terminal that it goes to is marked on top of the cap above the terminals. If it's a small-cap, then that's a different story.
04-09-2009, 07:29 PM #3
Yep, the HEI distributor needs only 1 power wire to run. But it's gotta be good, clean power. If you have power to the thick red wire marked B+ it should run. Those things sometimes lost the module under the rotor in the distributor- I used to carry a spare with me everywhere.
04-09-2009, 09:34 PM #4
So if I understand correctly...
- If I have 12v from the ignition when it is in the "on" position to the BAT+ side of the coil that should give me fire to keep it running.
- Do I need to find 12v from the ignition in the start position as well so it fires when turning over? Or can both be accomplished with one wire?
-The back of the ignition has a "IGN 1" and "IGN 2". Was not sure which or both of these to run from......
For a little history, when I got the truck the ign was wired up but hanging loose from the dash. He had 2 wires both spliced into another yellow one going to the coil but on the ( tach - ) terminal and nothing was on the "BAT" side. Truck is a 57 chevy and has no tach. It would start and run but seemed to only fire after the key was released from "start" and got in the "run" position. I also could not leave the battery connected because it would drain. Drove it around the block the other day and when I got back and turned it off it backfired and quit. Would not start again. Needed new plugs and all that anyway so I figured may as well do it all at once. When I was changing the cap I wsa reading the directions, noticed the one wire he had that seemed to go to the wrong place, so then I was really confused.
That is when I figured I better get a diagram and start with the min to get it to start and run. Of course since this truck is old and has a different motor is not the easiest thing to find. Plus I don't know much! I usually can follow directions though so that is how we got here.
And yes, if you like I will post pics of the truck. Pics are some type of requirement here if I remember correctly
really, thanks for the info. Especially since I am still (temporarily) scramblerless.....
04-09-2009, 10:21 PM #5
That originally came with a ballast resistor which dropped the voltage when the key is on but had another wire that supplied battery voltage during cranking. That's probably where your problem is. You need to find a good 12V when cranking and in the run position too. Also, don't feed anything else off of that wire like an electric choke. That can cause issues also.
04-11-2009, 07:48 AM #6
So either IGN 1 or IGN 2 should give me power when cranking and in RUN. ( I should be able to just test that w/a meter, right? I'll put one good wire from there and give her a shot.
04-11-2009, 11:07 AM #7
Good plan. Use the test light and run a dedicated wire to the B+ distributor terminal.
You mentioned in your previous post "He had 2 wires both spliced into another yellow one going to the coil but on the ( tach - ) terminal and nothing was on the "BAT" side" Is the coil separate from the distributor? We've been giving instructions for a GM large cap HEI, in which the coil is integrated into the distributor cap. And...I don't think there is any way a large cap HEI will run without power to the B+ terminal.
04-12-2009, 10:12 PM #8
You all have been right. Large cap HEI w/coil in it. I pulled out the ignition, rechecked the wiring on it. His 2 wires were supposed to be going from IGN 1 ( for run position) and IGN 2 ( for cranking?) and were then crimped to a single wire running to the coil. I made sure it was getting power during both, rechecked the plug gaps and wire positions, and ran it to BAT + on the coil. She fired right up and runs smooth. Idles a bit high but I need to check timing and get the carb adjusted probably too.
I went and bought some 10g wire and I am going to replace the power wire(s)to the coil. I think that ign switch may be going bad anyway, I can't seem to get power in the ACC position.
Thanks again for the help. I know it is probably simple stuff to most of you but there is no one here by me to bounce stuff off of. Throw in the ign wired up a little off and the coil wire not looking right and I started second guessing everything. Made my day yesterday to have that fire right up, it had been sitting for a couple weeks cause my time is pretty limited. Sometimes those small victories are great for making you feel like your getting somewhere!