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  • May 23, 2022, 03:16:32 AM

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Author Topic: Switched 12V for HEI  (Read 1103 times)

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Offline atmafox

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Switched 12V for HEI
« on: July 30, 2021, 01:07:42 PM »
Where do I use to get this?  The I terminal on the starter solenoid only gives around 10-11V and that's what feeds the current coil.

Thanks!
-Atma
Mine:
- 1980 AMC Eagle 2dr Sedan
- 2009 BMW 335i xDrive Coupe

Ours:
- 1986 Toyota Pickup

Hers:
- 1988 Toyota Supra Turbo
- 1988 Toyota Celica All-Trac
- 1997 Toyota RAV4 2dr 4x4

His:
- 1985 Nissan 720 Pickup Deluxe King Cab 4x4

Offline amcfool1

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Re: Switched 12V for HEI
« Reply #1 on: July 30, 2021, 11:32:14 PM »
hi, that's the terminal  "I"  that I used, and it worked fine for 20+ years. check your connections.  good luck,  gz

Offline atmafox

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Re: Switched 12V for HEI
« Reply #2 on: July 31, 2021, 10:31:35 AM »
My Davis Unified Ignition coil pretty specifically calls for more voltage than that so I haven't wired anything in yet.  So no connections to check yet.
Mine:
- 1980 AMC Eagle 2dr Sedan
- 2009 BMW 335i xDrive Coupe

Ours:
- 1986 Toyota Pickup

Hers:
- 1988 Toyota Supra Turbo
- 1988 Toyota Celica All-Trac
- 1997 Toyota RAV4 2dr 4x4

His:
- 1985 Nissan 720 Pickup Deluxe King Cab 4x4

Offline amcfool1

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Re: Switched 12V for HEI
« Reply #3 on: July 31, 2021, 12:59:56 PM »
hi, I meant the existing wiring, corrosion, old age etc. there should be 12V there. Again, that's where I fed my DUI from, no problems. good luck, gz

Offline atmafox

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Re: Switched 12V for HEI
« Reply #4 on: July 31, 2021, 03:39:02 PM »
Ah, disconnecting the ECU was the trick.  With that unplugged we're getting enough voltage.

Unfortunately I'm not getting fire but do have some indications of spark from the timing light.  Hoping it's just my mechanical timing being way way off.  Going to debug it more when it's not threatening rain.
Mine:
- 1980 AMC Eagle 2dr Sedan
- 2009 BMW 335i xDrive Coupe

Ours:
- 1986 Toyota Pickup

Hers:
- 1988 Toyota Supra Turbo
- 1988 Toyota Celica All-Trac
- 1997 Toyota RAV4 2dr 4x4

His:
- 1985 Nissan 720 Pickup Deluxe King Cab 4x4

Offline Taylor

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Re: Switched 12V for HEI
« Reply #5 on: July 31, 2021, 09:43:34 PM »
I wired the power for mine from the keyed ignition. Through a relay with the power source directly from the battery.
I haven’t been able to find the actual instructions or the wiring diagram. When I find it I’ll post it.
I had also done the ECM ECM Test bypass years ago.
« Last Edit: August 01, 2021, 09:36:18 AM by Taylor »
2010 Toyota Rav4 Daily Driver (better mileage and family beater)
1985 AMC Eagle Limited Wagon 🖖🏼🦅 Eats Audi quatros for breakfast😎 Official Member of the Land Rover recovery team.
2005 Ford Excursion 4X4 wife's around town daily driver and family pack mule.
2020 Honda Africa Twin for whatever...

Offline atmafox

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Re: Switched 12V for HEI
« Reply #6 on: August 02, 2021, 04:07:20 PM »
Ok I'm putting a call out to anyone in the greater Denver metro that can help.  I'll offer a case of your favorite beer or whatever else is desired because the wife and I simply cannot get the motor to catch with this HEI.
Mine:
- 1980 AMC Eagle 2dr Sedan
- 2009 BMW 335i xDrive Coupe

Ours:
- 1986 Toyota Pickup

Hers:
- 1988 Toyota Supra Turbo
- 1988 Toyota Celica All-Trac
- 1997 Toyota RAV4 2dr 4x4

His:
- 1985 Nissan 720 Pickup Deluxe King Cab 4x4

Offline vangremlin

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Re: Switched 12V for HEI
« Reply #7 on: August 02, 2021, 07:44:57 PM »
Did you pull out the standard distributor to replace with the new HEI?  If so, if you reinstall the standard distributor, does it go back to working?

I have an HEI that I used to have in my Kammback, you're welcome to try plugging that one in and see if you get any different results.  I'm in Centennial CO.
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline Illeagle1984

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Re: Switched 12V for HEI
« Reply #8 on: August 02, 2021, 08:39:56 PM »
Good test vangremlin, to see if the old parts work.  That would make sure the rest of the car is sound.  I am more than 1,000 miles away but I will try to help as well.  There are some quick things to check.

1.  You said it it will blink a timing light.  You can check timing while cranking; if you put the clamp on #1 cylinder, it should be on the timing marks even at cranking speeds.  If it's way off, you may be off a tooth or two on the gear.  If you're many teeth off, it can either backfire and sputter while cranking or wheel over like it has no spark.  Even if it's right on, it could be so far off it's firing on exhaust instead of compression.  The rotor would need to be rotated 180 degrees in that scenario.

2.  Open the choke and move the throttle to wide open while looking down the carb with a light.  You should see the accelerator pump squirt a jet of gas into the bore.  If not, your carb and fuel lines could be dry.  I don't know how long the job took, but both my Eagles take forever to get fuel back to the carb after sitting more than a few weeks.  If there's no fuel, a quick shot of starting fluid should light it up long enough to confirm it will run.  Use caution and do not attempt if it backfires or doesn't sound good while cranking.

3.  Make double sure the firing order is good.  Also make sure that rotor can't be installed backwards.  Always gotta double check the basic things when you put new parts in and they seem not to work.  With engine turned to TDC on compression the rotor should be pointing near the #1 wire on the cap.  Also what's your key-on power wire situation?  If the red/green resistance wire for the stock coil is anywhere in your power wire, it may mess with your new setup.

4.  Check for actual spark.  I use a $10 spark tester, get the one with a real gap instead of the test light style with a bulb.  Though I know that depending on where you live in CO, you can't just run down to the parts store quick.  So you can put any old spark plug on the end of one of the wires and lay it near the shock tower or somewhere else metal where it won't fall while cranking.  Crank while you watch and listen for spark.  If you used a plug out of your engine, watch for compressed fuel spray.  It should easily jump the plug gap and the gap from the plug to the car and make a crisp little snap.  HEIs can usually jump an inch gap with no problem.

If none of that reveals a problem, there's lots more we can check.  I'm just in it for the reward beers.  ;)
It's getting crowded down here:
1973 Ford Mustang "Rustang"
1984 AMC Eagle Sedan "IllEagle" 183k
1984 AMC Eagle Wagon
1996 Cadillac Eldorado 178k
1998 Oldsmobile Eighty-Eight 239k
2002 Cadillac Eldorado Doral Edition
2005 Chevrolet Silverado 1500

Offline Taylor

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Re: Switched 12V for HEI
« Reply #9 on: August 02, 2021, 09:30:45 PM »
This is how I wired mine. I bought a redline GM style HEI from Clifford Performance. The one thing not shown in the wiring diagram is the coil. It is built into the cap and is also replaceable.
I wired exactly as shown.
I did add a diode to the alternator. Helps prevent run on. Bought 2 on eBay for about $10.00
Check your hounds too. The one from my distributor to ground wasn’t good. Took a bit of time to figure that one out.
My internet connection is sub par. I’ll try and post the wiring diagram tomorrow.
« Last Edit: August 03, 2021, 10:18:48 PM by Taylor »
2010 Toyota Rav4 Daily Driver (better mileage and family beater)
1985 AMC Eagle Limited Wagon 🖖🏼🦅 Eats Audi quatros for breakfast😎 Official Member of the Land Rover recovery team.
2005 Ford Excursion 4X4 wife's around town daily driver and family pack mule.
2020 Honda Africa Twin for whatever...

Offline atmafox

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Re: Switched 12V for HEI
« Reply #10 on: August 02, 2021, 11:02:16 PM »
Thanks folks.  Do need to get a spark tester, plan to go by harbor freight tomorrow to get one.

Grounds are fresh - nice big tough wire the wife put together.  Haven't been able to find the timing marks with the timing light so may actually be 180° off, unsure there.  Hard to lock in when it's compression not exhaust without taking the valve cover off unless I'm missing some trick.

Carb is not dry, had just run her before taking the old dizzy out to make sure everything was working as expected before we did and work.
Mine:
- 1980 AMC Eagle 2dr Sedan
- 2009 BMW 335i xDrive Coupe

Ours:
- 1986 Toyota Pickup

Hers:
- 1988 Toyota Supra Turbo
- 1988 Toyota Celica All-Trac
- 1997 Toyota RAV4 2dr 4x4

His:
- 1985 Nissan 720 Pickup Deluxe King Cab 4x4

Offline atmafox

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  • Posts: 102
  • Thumbs Up 6
Re: Switched 12V for HEI
« Reply #11 on: August 04, 2021, 09:04:02 AM »
Yup, it was the timing.  Finally got her to fire yesterday after repeated attempts to get the timing lined up, then from there was able to dial it into where it needed to be.

I must say, this Davis Unified Ignition setup already has her sounding happier in the midrange revs even without opening up the spark plug gap.  I'll open them up to 40 or 45 thous and see how that goes, not sure yet.

First actual upgrade to my Eagle!  All the rest has been chasing repairs, so it's nice to actually be improving things beyond where factory would have been.  If anyone needs a full ignition set including ECU I'll be happy to sell my old one with fresh dizzy, coil, and plugs for a reasonable amount as soon as I'm all done verifying the upgrade performs in all conditions.  (I'm a little concerned she might break up under heavy load right now due to relatively low voltage still on that switched 12V off the ignition solenoid.)

Thanks for the help, everyone!
-Atma
« Last Edit: August 04, 2021, 09:04:48 AM by atmafox »
Mine:
- 1980 AMC Eagle 2dr Sedan
- 2009 BMW 335i xDrive Coupe

Ours:
- 1986 Toyota Pickup

Hers:
- 1988 Toyota Supra Turbo
- 1988 Toyota Celica All-Trac
- 1997 Toyota RAV4 2dr 4x4

His:
- 1985 Nissan 720 Pickup Deluxe King Cab 4x4

Offline vangremlin

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Re: Switched 12V for HEI
« Reply #12 on: August 05, 2021, 11:13:48 AM »
Glad to hear that you got that worked out.  That is a nice upgrade from the standard setup with the little tiny distributor cap lol.  Happy motoring!
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

 

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