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Discussion Starter · #1 ·
So i just got my hei distributor installed, and got the jeep started. I now have two questions. 1- when setting the timing, should the vacuum line be disconnected and plugged like a traditional distributor, or left connected? 2- on initial startup, everything was fine, and I shut it off via the ignition switch after 1-2 minutes. After cleaning some things up, i started it again, and let it run 10-15 minutes to warm up. When i went to shut it off, it wouldn't shut off with the ignition switch or even by disconnecting the positive battery cable. I wound up choking off the carb throat. Any reason this would happen, and what's the correct remedy? TIA.

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Did you install the HEI using a relay? I had to install a diode from Radio Shack in the alternator resistor wire because there was just enough back flow of current to trigger the relay and keep it open even though the ignition was off.


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Discussion Starter · #3 ·
I did install using a relay, but after reading a bunch, I'm wondering if I can just use the power supply that fed the ignition module previously. If I stay with the relay, who carries diodes, since i think Radio Shack is a thing of the past...?

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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I did not use the relay, never had a problem. Finishing the second one in the new Sahara today, we'll see how that goes. Here is the Instructions from summit on initial timing. You start with the vac advance capped. (Both ends).

Sorry, pics came out sideways, maybe L.M. can spin them.

Good Luck.
 

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I did install using a relay, but after reading a bunch, I'm wondering if I can just use the power supply that fed the ignition module previously. If I stay with the relay, who carries diodes, since i think Radio Shack is a thing of the past...?

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I must鈥檝e been lucky to have had one of the last existing RadioShacks in the town I lived in in Tennessee. Haha. I imagine you might just need to cross reference the model number of the diode from their website which is still up. I鈥檓 not home at the moment but if I think about it I鈥檒l see if I can find the packaging in my toolbox and reply back.

As far as going without the relay, I initially wired mine up with no relay and then changed it to include the relay. There are some that say it鈥檚 the 鈥減roper鈥 way to do it, but they鈥檙e really aren鈥檛 any noticeable performance or efficiency gains by using the relay, and whatever increase in voltage you get probably isn鈥檛 important since these aren鈥檛 exactly hot rods. If my OCD can overpower my laziness, I might get back into it and re-wire without the relay to reduce a little bit of engine clutter.

If you keep the relay, you鈥檒l probably need the diode.


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I had the same issue when I first installed my HEI.
You need to find a wire that's cold with the key off and hot in the start & run positions.
Use that wire to trigger the relay.

What's happening now, is the alternator is supplying current to the relay when the engine is running. If you turn the key off, the engine continues running because the alternator keep supplying current to the relay and thus, to the distributor.

Good Luck, L.M.
 
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This is the diode with the part number. If you can find a local store they should have it in stock. If not, surely Amazon or something will have one that will work.




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I had that problem once 20+ years ago with a demo derby car I had wired up... I had used a toggle switch for ign on and had the hei and alternator on the same circuit thus as mentioned above tbe alternator was powering the coil... the solution was to add a second toggle and a second circuit...
The manufacturers handled the problem w two circuits on the ign switch, ign and accy on older vehicles or ign 1 (or a) and ign 2 (or b) on newer ones...

Sooooo on your jeep you need to have the ign powered by a source that is separated from the alternator when turned off....

BTW... GM never used a relay to power the HEI....
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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You can use this orange (2.5 fuel pump) wire to power the HEI, Runs through the ignition switch (Key on) if you don't want to use a yellow. I used the yellow without the relay, without an issue on the Red Laredo.
 

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Discussion Starter · #10 ·
Thanks for the info. I wired the relay trigger to the yellow wire going to the original ignition module. When I tested it, it was dead with the key off, hot with the key on. I'm guessing my issue might be feedback from the alternator circuit. I know a diode could fix that, but I might give it a shot wiring the distributor direct. I'll decide when I get back in the shop. Certainly happy with the results so far, even if it doesn't shut off!

Got it at last- I had the instructions for setting the timing, but just completely overlooked them; I think I read them and immediately forgot! Thanks for the reminder!

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Discussion Starter · #11 ·
So I wound up disconnecting the relay power, and connected the yellow wire I had used to signal the relay directly to the distributor. Jeep shuts off with the key now! I guess the bleed back from the alternator is an issue. I was able to adjust the timing as well, have it set at 8掳 with the vacuum disconnected. Seems to be running fairly well. I'm going to start cleaning up/removing vacuum lines tomorrow, then hopefully I can get it out of the shop and road test it. Thanks again for all of the info/pointers so far!

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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I think the relay bypasses the resistor wire that already runs with the alternator wire to where the yellows all tie together in the center of the harness, Cant explain it, just happens.

When you start pulling out wiring, Make sure to identify the oil pressure switch, coolant sensor wire at the back of the manifold, choke wire, hood light, and A/C wiring if you have it. Everything else pretty much goes.
 

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Finished, mine up on the Sahara couple days ago, I kept a yellow lead off both sides of the harness for a "key on hot" for later accessory add on's, You'll have a few extra once you get onto the harness deeper.
 

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Discussion Starter · #14 ·
I'm not sure how much wiring I'm going to "remove" as opposed to cleaning up and tying back. I'll probably work piece by piece, getting everything running right first, then go back and clean up. Vacuum lines are going to get cleaned up though. I'm trying to work through that now. I'm going to need to do a valve cover gasket, so the less in the way, the better.

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There鈥檚 a pretty good amount of wiring that can go. No use in keeping it. For example, the diagnostic thingies on the passenger side are useless, and anything connected to the PCM is no longer functioning.


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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Not to mention all the plugs for all the valves and solenoids that have no home or use anymore
 
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I also had to use a relay,hooked up to the battery. It would run but at higher RPM's it would back fire and would not go faster.

I got my diode off of ebay. I plugged it into the alternator.




Did you install the HEI using a relay? I had to install a diode from Radio Shack in the alternator resistor wire because there was just enough back flow of current to trigger the relay and keep it open even though the ignition was off.
 

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I鈥檓 not sure. That鈥檚 a little more complicated than what you need. It鈥檚 just the tiny brown wife connecting the alternator to the main loom that needs the diode.


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ya know, I had this same issue, "engine run-on", while I was readin this thread brushin up on my new Summit HEI distributor swap tips and tricks, I read how jar06896 was now tryin to kill what he just brought back to life LOL. anyway, same thing happened to me. and like dsaylor said its that brown skinny, solid core "resistor" wire. i dont know about the diodes, i tried several on several different wires and..... nuthin! Then I read somewhere, not here, sorry dsaylor, about that "little brown wire" I had previously removed in my goal oriented pursuit of removing all the superfluous wiring from under my 87's hood. Proof of what Got it at last said. "one piece at a time and check for life,
Anyway, to make a long story, haha, a little longer. i put the brown wire back in, no resistor. and low and behold. She shut down and never an issue with run-on since. if any of yall know where I can get some if that resistor wire Id like to replace mine, I had to put heat shrink all up and down it cuz it had cracked so bad over the years. So i tolk some pics of my wiring but don't see where to upload them. Anyway, you have a yellow wire coming from your ignition to the ignition, and a yellow and a green wire from the ICM. I bundled thise three on one side of a 10-12ga connector, and put a green wire w/black strip (runs to the solenoid post (batt. side)); a yellow wire w/ red strip (runs to the coil) and the beautiful brown wire (which is goes into the plastic insert which plugs into the alternator), Evidently the diode way works, just not for me. (Limited funds, hate to stop working on it, and it worked before without the diode) I will post the pics if someone will tell me how
 

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