HEI- Ignition conversion

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Holland Waggy
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HEI- Ignition conversion

Post by Holland Waggy »

Since I’ve bought the Wagoneer it has been running a bit rough, both in idle and at cruising speed. Cranking took a little longer then I liked as well. Now I was told that the Duraspark module is bomb-proof and hardly ever breaks down, but tuning the ignition and carb did’nt help much as well. The wiring harness looks like it has been attacked by a madman with an axe, so there’s a probable cause too. It’s about time to check all connectors and wires. My Waggy has a stock A/C unit, but surprisingly that never works and is probably empty as well. It has a retro-fitted for R-134 compressor mounted and my experience tells me that that 134 in an R12 system doesn’t work quite that well. Since all kinds of wiring hanging loose from the unit and it’s really in the way of reaching the underdash-cables I’ve decided to say goodbye to the complete AC-installation. It’s a bolt-on option, so let’s bolt it back off.

This was pretty easy and left me with lots of space under the hood and dashboard. After removing the dashboard cluster I’ve found all sorts of cables hanging out, some even with the clusterlights attached to them. Nothing seemed to work, I bought the car by daylight and I never thought of testing the lighting, so that ship has long sailed. Since I have a correct wiring diagram for a ’78 it would be a matter of following the correct lines an hold on the colors. So far I succeeded and most things were a matter of rewiring, or just re-attach a connector. I even got the cruise-command back to work by putting a standard 4-pin relay in the loom. Also the courtesy lights an dome lamps are doing their job now.

Under the hood there was a bigger problem. Someone had been tampering with the wiring and who knows for what cause. It seems like the auxiliary contact on the starter solenoid went bad and they made a shortcut to the starter-terminal to obtain full 12V during cranking. But for some reason they had to yank out the entire harness for that and cut it to pieces. So I’ve started by taking all out an take away all the wires I would’nt need in the future; The AC, the anti-diesel solenoid etc. Now I noticed that the car still had the original coil in it. It was all buckled and rusted but still seemed to produce a spark. All the connectors for the ignition where smashed, broken and filled with copper-grease or petrol-jelly. Cables had hardened over the years and where oxidized on the inside. So I decided to exchange the entire ignition for a HEI- ignition and ended up with a Mallory, which should give good value for money. I wired it directly to the IGN section on the fuse panel so I knew I had a clean powersource. Engine ran great and stabile. Even got some more torque when advancing the unit a bit more, mine runs on LPG so I can go pretty far with the static advance. But still, cranking took a few seconds. Probably, the HEI needs constant 12 V as bad as a Duraspark- unit. I now put a 5-pin relay between the IGN-source and a lead from the starter solenoid, so the ignition gets the full load at any time.

While I was at it, I decided to put in a cheap Central Door Locking system in. I scored one for around $20 and it works fine! I even have a spare channel left so I can add an extra function on the remote receiver. Remote starting sounds nice to have and is very good possible with a $5 timer relay, but that’s for future fun…
Gilbert Doggen

1978 Wagoneer, AMC360, TH400, Quadratrac, HEI Ignition, Headlight LED conversion,
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lkmarsh
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Re: HEI- Ignition conversion

Post by lkmarsh »

Wow. This sounds like Bill Murray describing the GhostBusters' ambulance. Also sounds like you know your way around wiring. Yes the HEI does want full-time 12V so no resistor wire is needed. Most of us have inherited a wiring nightmare from the previous owners. I gave up splicing and just replaced it all. Mine had no fuse block so that was the starting point. What headlights are you using?
Lyle
69 1414x Buick350/Th400/D20
PDB, HEI, relays, rallyes, rhino, rust...
73 Wagoneer parts donor
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Holland Waggy
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Re: HEI- Ignition conversion

Post by Holland Waggy »

.. It took a while for me to understand it myself but it happened :D I now know every wire in the entire car. I've ended up with a knock-off version of the JW Speaker 7". But I must say, they are a lot better than the stock beams! Wiring is also pretty straight forward so no complaints here.
Gilbert Doggen

1978 Wagoneer, AMC360, TH400, Quadratrac, HEI Ignition, Headlight LED conversion,
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Stuka
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Re: HEI- Ignition conversion

Post by Stuka »

When I do HEI conversion of duraspark equipped Jeeps, I use the main power feed going into the duraspark box as the 12V source for the HEI. Its a heavy gauge wire and is always 12V.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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Holland Waggy
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Re: HEI- Ignition conversion

Post by Holland Waggy »

Stuka wrote:When I do HEI conversion of duraspark equipped Jeeps, I use the main power feed going into the duraspark box as the 12V source for the HEI. Its a heavy gauge wire and is always 12V.
That's the same lead where the Anti Diesel Solenoid is spliced from. Mine gave only 9.2V on cranking
Gilbert Doggen

1978 Wagoneer, AMC360, TH400, Quadratrac, HEI Ignition, Headlight LED conversion,
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tgreese
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Re: HEI- Ignition conversion

Post by tgreese »

Which wiring diagram are you referring to? There is normally a circuit from the starter solenoid that bypasses the resistance wire to the coil during cranking. There would have been no need to add additional wiring.

Measure voltage at the battery while cranking and compare.

The red wire with a trace (stripe) at the module (13F) also goes to the carburetor solenoid. If the battery voltage during cranking is higher than at the module connection, trace back until you find where the voltage drops. It's a direct connection to the battery through the ignition switch. Do not mix up the resistance wire 13B with 13A or 13F.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
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Stuka
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Re: HEI- Ignition conversion

Post by Stuka »

Holland Waggy wrote:
Stuka wrote:When I do HEI conversion of duraspark equipped Jeeps, I use the main power feed going into the duraspark box as the 12V source for the HEI. Its a heavy gauge wire and is always 12V.
That's the same lead where the Anti Diesel Solenoid is spliced from. Mine gave only 9.2V on cranking
Different wire. The main feed for the duraspark module is not behind the resistance wire, its a full 12V and comes from the ignition switch.

What tgreese says above is spot on.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

MischenFSJ
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Re: HEI- Ignition conversion

Post by MischenFSJ »

I will be installing an HEI distributor soon. My ICM gave out on me the other day. Since the Jeep needs. New coil, cap, rotor, etc... I'm just upgrading at the same time. I can post the details when I'm done with it if you like.
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Holland Waggy
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Re: HEI- Ignition conversion

Post by Holland Waggy »

Please do!
tgreese wrote:Which wiring diagram are you referring to? There is normally a circuit from the starter solenoid that bypasses the resistance wire to the coil during cranking. There would have been no need to add additional wiring.

Measure voltage at the battery while cranking and compare.

The red wire with a trace (stripe) at the module (13F) also goes to the carburetor solenoid. If the battery voltage during cranking is higher than at the module connection, trace back until you find where the voltage drops. It's a direct connection to the battery through the ignition switch. Do not mix up the resistance wire 13B with 13A or 13F.
I'm not referring to the resistance wire. It's the R w/TR that is spliced into the feed for the ADS and the duraspark unit. Battery delivers enough, but measuring at this wire gave me 9.2 V during cranking at least. That's why I pulled some extra wires. But as I understand it should be 12 V under any circumstance. Perhaps there's a problem with the connection at the panel or maybe the ignition switch itself.. Another reason for some deeper inpection!!
Gilbert Doggen

1978 Wagoneer, AMC360, TH400, Quadratrac, HEI Ignition, Headlight LED conversion,
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Stuka
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Re: HEI- Ignition conversion

Post by Stuka »

Holland Waggy wrote:Please do!
It looks like you went to respond to tgreese, but instead hit the report button. I added that text to your post above.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

MischenFSJ
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Re: HEI- Ignition conversion

Post by MischenFSJ »

I just got the Jeep back up and running. New HEI Summit brand distributor, new plug wires, new spark plugs, and a couple hours was all it took.

The ICM was melted all over my inner fender, pretty clear indicator that it was done. All I has to do was change the connector from the coil to be a female spade terminal, which was what the new HEI distributor has. I was fortunate in the fact that I was able to use the + feed that used to go to the coil. I checked with my multimeter and I have 12v at crank and run. After some research, it seems the prestolite distributors got 12v to the coil at all times.

I will try to get pictures soon.
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Holland Waggy
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Re: HEI- Ignition conversion

Post by Holland Waggy »

What year is your Waggy? Perhaps there's a difference in wiring. The '78 coil is fed through a resistance wire. So never 12V here..
Gilbert Doggen

1978 Wagoneer, AMC360, TH400, Quadratrac, HEI Ignition, Headlight LED conversion,

MischenFSJ
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Re: HEI- Ignition conversion

Post by MischenFSJ »

Mine is a '77 Cherokee with 360. I can't find much but it does seem there was a change from prestolite in 77 and that 78 and later got 9 volts to the coil.
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tgreese
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Re: HEI- Ignition conversion

Post by tgreese »

1978 was the first year for the Motorcraft Duraspark ignition system. A '77 came with the Prestolite BID system which uses no resistance wire.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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vajeepj20
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Re: HEI- Ignition conversion

Post by vajeepj20 »

For what it's worth, aside from electrical issues with it, if you start having timing problems or the engine starts running rough, bad, or not at all, check out the distributor drive gear on the camshaft. I did a HEI swap a while back on my J20, everything seemed fine at first, shortly after it started running like crap, then not at all. Before doing the swap I had read that the factory gears were made of softer metal than what is common on newer distributors and that the new distributor gear CAN eat up the cam gear. Even after reading that I went ahead and took the chance without addressing the cam gear. Looking down inside the distributor hole, from what I could see, the gear looked okay. When I would crank the engine the distributor rotor seemed to spin normal. I finally tore everything down to find that the hardened HEI gear had wore the cam gear down in a pretty severe concave pattern. It definitely had me stumped until I tore it apart. While I was in there I changed the timing chain as well, it was stretched pretty good.

If you or anyone else needs a matched gear set for the Jeep/AMC V8, Crown makes a set that is reasonably priced, Crown part # 4486635K. You can get them at Team Grand Wagoneer.

https://www.teamgrandwagoneer.com/distr ... 1974-1991/

I've actually seen HEI distributors with spark plug wire sets for the Jeep/AMC V8 on Ebay that says they already have a compatible gear on them. That would be great for anyone who wants to switch to HEI but doesn't want to tear apart the front of their engine.

https://www.ebay.com/itm/AMC-JEEP-V8-29 ... :rk:2:pf:0

https://www.ebay.com/itm/AMC-JEEP-1967- ... :rk:8:pf:0
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