HEI Troubleshooting
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Joined: May 2007
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From: Cocoa Florida
HEI Troubleshooting
Please help me troubleshoot my new HEI unit that came with my ZZ4 crate motor. Upon installation, the motor initially ran but not very good. After checking the timing and plug wire order (again), it "tries" to fire but wont. I'm convinced the timing and plug wiring are correct, but even if it was off a tooth or wires crossed it should backfire and carry on. Not in this case. How do I troubleshoot the coil and modules? Does the spark plug gap need to be increased? Any help to relieve this frustration would be appreciated. Thanks
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Drifting
Joined: Dec 2002
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From: Long Beach CA
Check the power feeding the distributor. It should be battery voltage. And you should be using a 10 or 12 gauge wire to supply that voltage.
When you crank the engine, will it fire a timing light hooked to No. 1 plug wire? If so, you should have adequate voltage for the engine to start. Plug gap isn't critical to getting the engine running, but timing is. Check the timing with someone cranking the engine and see if it's near spec. Get a can of starting fluid and spray that down the carb. If it fires and tries to run, you don't have a spark issue.
When you crank the engine, will it fire a timing light hooked to No. 1 plug wire? If so, you should have adequate voltage for the engine to start. Plug gap isn't critical to getting the engine running, but timing is. Check the timing with someone cranking the engine and see if it's near spec. Get a can of starting fluid and spray that down the carb. If it fires and tries to run, you don't have a spark issue.
Pro
Joined: Apr 2008
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From: Pine Barrens New Jersey
You can troubleshoot the module with a spare or an MSD box if you had one. Sometimes the thingy under the coil for transferring coil output to the rotor gets screwed up (its a common blunder). Also check the rotor and cap for any cracks, bends, breaks or other problems. Incorrect distributer cap seating can also be the culprit. If its new I would guess its not the module (unless you somehow fried it).
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larry
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From: Cocoa Florida
HEI Troubleshooting
Yes, easy thing to mix up. The 12V wire to the HEI should come from the same source that is connected to the wire coming through the firewall from the ignition switch. This normally goes to the top of the register block. You don't want to use the wire from the other side of the register block.
larry
larry
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From: Cocoa Florida
HEI Troubleshooting
The wire going to the "BAT" terminal of the distributor is the ignition switched pink 10 g wire and it reads battery voltage (14 v) with the ignition on. The ballast resistor is removed. Between the firewall and distributor, I have spliced into this wire to go to the starter. Is this where I screwed up? Do I need to instead run another wire to the starter. To me this just relocates the point of the splice.
Today I put a brand new distributor in and it does the same. It will not start. I'm convinced the timing is correct. The coil from yesterday's distributor is toast (my fault probably).
Today I put a brand new distributor in and it does the same. It will not start. I'm convinced the timing is correct. The coil from yesterday's distributor is toast (my fault probably).
Melting Slicks
Joined: Feb 2006
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From: Sunrise FL
get somebody else to check all the plug wires etc. Getting ANY spark? got the batt term in the right spot?
VERIFY TDC...crank engine (or turn w/ breaker bar) with your finger in plug #1 hole...feel for compression and line up timing pointer. The rotor should be pointing to #1 cyl wire. It is VERY easy to be 180 off!!!!
VERIFY TDC...crank engine (or turn w/ breaker bar) with your finger in plug #1 hole...feel for compression and line up timing pointer. The rotor should be pointing to #1 cyl wire. It is VERY easy to be 180 off!!!!
Advanced
Joined: Oct 2004
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From: Northeast Ohio
Once you remove the ballast resistor, that power lead should feed the
coil on the HEI distributor. Do not hook the wire from the solenoid to
the distributor as it was in the breaker point igintion. This was originally
used to provide current upon starting. You only need the large positive
lead on the solenoid and the purple wire which activates the starter
from the ignition switch. I hooked up a buddy's Chevelle last week and
he was having the same problem. Plus he had the distributor 180 degrees out. Do a google search and you should find pics too.
coil on the HEI distributor. Do not hook the wire from the solenoid to
the distributor as it was in the breaker point igintion. This was originally
used to provide current upon starting. You only need the large positive
lead on the solenoid and the purple wire which activates the starter
from the ignition switch. I hooked up a buddy's Chevelle last week and
he was having the same problem. Plus he had the distributor 180 degrees out. Do a google search and you should find pics too.
Drifting
Joined: Dec 2002
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From: Long Beach CA
Don't have a wiring diagram here, so I don't know the wire colors -- but check that pink wire. It has battery voltage with the ignition switch in ON, but does it still have voltage with the switch in START? If it's losing voltage when cranking, the engine will never get spark and fire.
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From: Cocoa Florida
HEI Troubleshooting
The pink wire going to BAT connection on the HEI has battery voltage in the switch ON position. In the RUN position it is in the 9-10 volt range.
Rough week! To summarize, the car was running (but not consistently)with original style points distributor. Decided to change it out with new ZZ4 HEI that came with motor. Ran initially, but rough. Thinking I may be off a tooth, moved the timing. The car has not started since - not even close. Resistance checks showed the ZZ4 HEI coil to be bad. I checked the wiring, timing, plug wire sequence, thoroughly (again). Thinking the ZZ4 coil could have been bad when I first got it, I installed a brand new HEI distributor. Still no start, and I think it is now fried. That's what I get for thinking.
So, trying to return to where I started, I reinstalled the points style distributor. Now with spark the engine still will not start -won't even fire. A very experienced mechanic friend has been helping. Hard to believe and you must think I'm nuts. Thanks for all the help
Rough week! To summarize, the car was running (but not consistently)with original style points distributor. Decided to change it out with new ZZ4 HEI that came with motor. Ran initially, but rough. Thinking I may be off a tooth, moved the timing. The car has not started since - not even close. Resistance checks showed the ZZ4 HEI coil to be bad. I checked the wiring, timing, plug wire sequence, thoroughly (again). Thinking the ZZ4 coil could have been bad when I first got it, I installed a brand new HEI distributor. Still no start, and I think it is now fried. That's what I get for thinking.
So, trying to return to where I started, I reinstalled the points style distributor. Now with spark the engine still will not start -won't even fire. A very experienced mechanic friend has been helping. Hard to believe and you must think I'm nuts. Thanks for all the help
Le Mans Master
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From: MA
1982, bat, connected, corvette, distributor, hei, module, no1, plug, position, recommendation, shoot, trouble, troubleshoot, troubleshooting, wire, zz4
