So I rebuilt a T Bucket, running car. Put it back together and the ignition is acting up. Dist is in right, plug wires are correct, tried two separate coils and distributors. New battery and voltage when cranking at batt terminal to dist is 9.45 volts. It tries to start but won’t, when you stop cranking it backfires out both pipes. Battery is grounded straight to engine via a trans bolt. Havent run a chassis ground due to not having hooked lights up yet. Any suggestions?? Sent from my iPhone using The H.A.M.B. mobile app
Inside is there a black two wire connector that goes from the module to the pickup coil under the rotor? IIRC one wire is green and the other is white. Take the plug off the module, take an ohmeter and probe both terminals in the connector. Now wiggle and move that little harness and watch the meter. If it goes open circuit you have a wire breaking contact to the coil. Replace coil, problem solved. While not a common problem it is a problem that can be found with HEI's.
I'd have to figure out why you are loosing so much voltage to the distributor when you are cranking. Do you get a full 12.5 volts when it isn't cranking? In my photobucket album I have the pages of a Napa HEI troubleshooting bulletin that I copied a few years ago. The Napa rep gave me the Bulletin years ago when he gave a workshop for my students. You may have to save it to your laptop and expand it to be able to read it but it is there for any and all to use. It pretty well walks you through troubleshooting pre computer HEI distributors. http://s173.photobucket.com/user/mr48chev/library/Napa HEI service info bulletin?sort=3&page=1 I printed a copy out for a friend years ago and he used it to troubleshoot his motor home distributor on the side of the road on vacation. Rode his bicycle to the next town and bought the part and rode back and got the motorhome going. I am not positive the pages are in the exact order that they should be.. It may skip around a bit until you figure out the order of it.
One thing I have found out the hard way was that a regular female slide terminal out of your wiring terminal box can loosen up just enough to not make good contact with the terminal on the cap and cause issues. My OT truck left me stranded all too many times usually when it was raining like a cow peeing on a flat rock on the way to work at 3:30 am
I am totally no expert, but did get caught myself a couple of years back trying to run thr wrong external coil on my HEI dizzy. So if your coil is an external stand alone type then be sure it is the right coil for HEI purposes. Other than that I don't know, but wish you luck in finding the problem soon...
I think you have the distributor timed wrong. Double check that you are on Tdc #1 on the compression stroke. Bump it over with a compression gauge in #1 to easily check.
If your having the same problem with 2 distributors its your wiring. The backfire is telling you something . Do you have the electric fans or other device wired into the same line as distributor?
What you can try is this. Disconnect the BAT and TACH wires from the cap. Run a wire from positive side of battery to Bat in the cap. See if that fixes your problem. IF it does while running reconnect the tach wire to make sure that wasnt the problem.
If you have the usual coil-in-cap HEI, take off the coil cover and check the wire colors. If you have the "white wire coil", pull it out and buy the "yellow wire coil". The yellow wire coil has a higher transformer step-up and works much better when you have a large voltage drop during cranking. I did that when putting in a huge Caddy engine, and it cured a hard-start problem years ago. No more hard start problems. If that doesn't do it, chase down the cause of the big voltage drop (bigger cables, etc). HEIs like full voltage, and dislike low voltage. That's one of the reasons why it's still worth running an alternator on a drag car. WHY BE ORDINARY ?
It's been said already, but by pass all wiring from car and hook distributor directly to battery terminal with 12 gauge wire and solid clamps. HEI needs full battery power to run correctly. If it runs, check all connections from switch out, if it doesn't, then check internals of distributor, and be sure you are at TDC on #1 cylinders compression stroke when setting distributor in place. 99% of the time, HEI modules work correctly till they don't, you rarely will ever find on half ass working. The small wires from the pickup coil go bad from rotation from the vacuum advance. Here is a very good HEI guide, index.php .
Nothing else wired, just purple to starter, red to Batt of ign sw and pink to HEI. I even separated out the pink and put it on a separate switch. Battery is new and cranks over great. Sent from my iPhone using The H.A.M.B. mobile app
Ive never run an HEI dist. but seems to me I read that you need the full 12 volts with the resistor or carbon core wire(as the case may be)bypassed or removed, as that 9.45 volts you posted ain't gonna get it.
I have run quite a few HEI , some of them would shutdown at 9 volts I have had others that would run on 8 volts.If it was me I would be checking on that 9.45 volts .May very well be that module is not firing at that voltage,no reason you shouldn't be seeing 12 volts there,,,jumper 12 volts like suggested previously,,
Backfire after stopping cranking says to me the distributor is not getting spark in the start position but is getting spark in the run position. Is the ignition switch wired correctly? If you hot wire it as recommended above, it will start even if the ignition switch is not correct. The 9.45 volts bothers me, too.
Some ignition switches are designed so that you have to have a resistor bypass wire in place to have voltage to the distributor to fire/start when you are cranking the engine with the key. Just thinking, you didn't by chance leave a resistor wire or ballast resistor in the line to the distributor that was left over from a point type ignition by chance?
No and I also went straight from Batt on ign sw to a separate switch. Sent from my iPhone using The H.A.M.B. mobile app
You may be wire directly from battery to ignition switch, then to distributor, BUT if the switch is not internally wired for IGN power in START mode, it will never start. Some switch supply power to IGN in START & IGN, some don't. Those that don't, have IGN wire coming from starter solenoid to distributor, so in START the distributor is feed full battery power right off starter solenoid.
Your clue is,it backfires when you release the ignition switch. Your HEI is not getting enough voltage. When you release the switch for a split second it’s getting the voltage it needs and fires, hence the back fire or an attempt to start. Make sure your HEI has proper voltage and your car will run. Bones
Yes, it will fire no problem on 9.45 volts. There was a combination of a bad coil in one distributor and module in another. Runs great! Sent from my iPhone using H.A.M.B.
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