Leanburn to HEI conversion question

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gliderider06

gliderider06

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I did the HEI conversion on my 318, 87 Ramcharger today. I used an electronic distributor, A design2drive.com adaptor plate, Pertronix flamethrower coil that was listed to use, and a Standard Ignition Products HEI module. I recurved the dist to one of the MP light springs, and a light blue spring. The mechanical advance plate is a 17r (giving me 34* mechanical advance) and I did no modifications to it.
I set the timing to 16* and total mechanical timing is 45*. I DO NOT have vacuum advance hooked up B/C the factory leanburn 2bbl carb does not have a ported vacuum. I did also drill the idle mixture plugs out of the carb to adjust the idle mixture.
The issue i'm having is when its in park, it revs quicklyand runs really smoothly. When I drive it, it's a completely different story. Off idle it really sputters and hesitates to about (a guess 15-1800rpm) then picks up and runs fine. There is no spark knocking or valve pinging. It did not do this with the leanburn, just when I put the HEI on it today.
I am thinking/wondering that could it be advancing too quickly and/or is the total advance too much for it? I do also have another mechanical advance plate that is marked 15r (which would give me 30* mechanical advance). Should I put the 15r plate on and a heavier spring in place of the MP light spring? Could my problem be elsewhere?
 
I would guess "elsewhere" EXCEPT

Are you familiar with "rotor phasing? (Google it) You must have the HEI hooked up correctly (polarity) to the Mopar distributor.

This is "accepted".........

Referring to the factory distributor connector (not the color) the small lug on the HEI goes to the insulated terminal on the distributor, IE the "bare" terminal on the mating connector on the HEI end.
 
Here's the deal.
If the two wires connected to the HEI module that come from the distributor are reversed it will cause rotor a phasing issue like Del mentioned.
Easy to check by swapping the two wires and see if it runs better or maybe doesn't even start.
If it doesn't even fire up, then swap the wires back and now you know that is not the problem and you can continue the search.

There are two things that are critical with the HEI swaps and those are a good strong power source for the module and coil to run off of and a good ground for the module itself (even if you have to add a wire from one of the screw holes to a firewall or block ground.)

A relay can help here if needed to power the HEI and still function the exact same at the ignition switch, but it reroutes the voltage and amps using the relay instead of the power flowing into and out of the dash and switch, and then to your HEI.
This is usually only required if there is a problem getting a full voltage to the HEI and coil.
1. Make sure the pickup in the distributor is adjusted correctly. (if it wasn't test run)
2. Swap the distr to module wires and test fire it to see how it acts. ( is it better?)
3. If not then be damn sure of your power supply and ground for the module

All this checked and the problem not solved, then you might have a bad module or coil.
 
Thank you! I marked the rotor when I took it off and it is a good known distributor. I was very careful to go slowly and followed the directions when I soldered all the wires and terminal ends. I sure hope the coil is not bad, it was pretty expensive. The modules are cheap enough, and I could put another on and see if it still does it. I will recheck my wiring just to be certain. I used a .008 brass feeler gauge to set the air gap between the rotor and pick-up.
Could it be advancing too quickly/too much, thus causing the sputter? When I pull the distributor again to check the wires, I want to change the advance if that could also be part of the culprit.
 
I doubt it. Did you check reluctor gap? .008" (inches) with a brass feeler. Last I got some were at O'Reallys
 
gliderider06 said:
Thank you! I marked the rotor when I took it off and it is a good known distributor. I was very careful to go slowly and followed the directions when I soldered all the wires and terminal ends. I sure hope the coil is not bad, it was pretty expensive. The modules are cheap enough, and I could put another on and see if it still does it. I will recheck my wiring just to be certain. I used a .008 brass feeler gauge to set the air gap between the rotor and pick-up.
Could it be advancing too quickly/too much, thus causing the sputter? When I pull the distributor again to check the wires, I want to change the advance if that could also be part of the culprit.
Click to expand...

The advance would be easy enough to diagnose just by turning the distributor back and see if the problem at light throttle gets better, or goes away.
2 min to check and eliminate or verify.
 
I know this may be redundant, but did you get rid of the ballast resistor, and connect the wires back together without it? It jay be getting just enough spark for idle but not so much under load. HEI requires a full 12V the ballast drops that to 6V. Thats no bueno.

Typically the wire connections are green to black, orange to white if making an HEI to mopar adaptor, or soldering the GM plug to the mopar dist pickup.

Hope this helps
Matt
 
moparmat2000 said:
I know this may be redundant, but did you get rid of the ballast resistor, and connect the wires back together without it? It jay be getting just enough spark for idle but not so much under load. HEI requires a full 12V the ballast drops that to 6V. Thats no bueno.

Typically the wire connections are green to black, orange to white if making an HEI to mopar adaptor, or soldering the GM plug to the mopar dist pickup.

Hope this helps
Matt
Click to expand...

You do know there are different wire colors that the mopar distributor pickups come with, right? :D
I have plugs with three different color combinations here right now.
That's why we have to mention swapping how they are connected, because it's so easy to make sure they are right that way instead of by color.

You can usually be reasonably sure it's connected right if you use the exposed male bullet as the positive on the distributor side of the plug.
 
TrailBeast said:
You do know there are different wire colors that the mopar distributor pickups come with, right? :D
I have plugs with three different color combinations here right now.
That's why we have to mention swapping how they are connected, because it's so easy to make sure they are right that way instead of by color.
Click to expand...

I did not know this. In all my years of messing with mopar electronic pickups on vac advance dizzys everything i have ever seen was black and orange, however a simple ohm check on tge mopar pickup will find the ground, and terminal G on the hei 4 pin is the ground on that end.
 
moparmat2000 said:
I did not know this. In all my years of messing with mopar electronic pickups on vac advance dizzys everything i have ever seen was black and orange, however a simple ohm check on tge mopar pickup will find the ground, and terminal G on the hei 4 pin is the ground on that end.
Click to expand...

Check it out.
All of these taken off OEM replacement distributors to have HEI connected to the distributor.
I take them off and wire directly to the HEI module because you can't always trust them to make the connection.
I have had two cars not start at all, or not restart after warmed up because of this type of connector.
 

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Ok. There is no ballast resistor on this truck. I researched it and found that from 86 up leanburn systems did not have a ballast resistor. I looked all through the wire harness and found nothing but a small resistor for the choke. I even un hooked it as well with no change. I used a .008" brass feeler gauge to set the airgap as well. I did retard the timing 5* with no change with the sputtering. I do have this exact same ignition set-up on my 69 Dart except it has a different coil. My leads coming from the pickup are gray/black. Without going out to look at it, I do believe the gray went to the small pin on the module and the black went to the pin next to the small pin on the module.
Could the air gap be too big and cause the problem? I was pretty certain that the gap was set correctly, but just throwing that idea out there.
Thanks again for all the help!
 
gliderider06 said:
Could the air gap be too big and cause the problem? I was pretty certain that the gap was set correctly, but just throwing that idea out there.
Thanks again for all the help!
Click to expand...

It is possible but in my experience close to 008 still runs fine.
It sure sounds like a voltage/amperage supply problem to me, but what do I know?

(RPM's come up, as does the charging system and then the HEI works fine, right?)
Could be, so I would check the voltage with the car running at idle and see what I have.
 
moparmat2000 said:
I did not know this. In all my years of messing with mopar electronic pickups on vac advance dizzys everything i have ever seen was black and orange, however a simple ohm check on tge mopar pickup will find the ground, and terminal G on the hei 4 pin is the ground on that end.
Click to expand...

There is no ground in a Mopar pickup. In fact either wire should read infinity to ground. I always go by the bare vs insulated terminal rather than wire color

To check voltage, turn the key to "run" with engine off. The hot side of the coil and the HEI module should both be same as battery
 
67Dart273 said:
There is no ground in a Mopar pickup. In fact either wire should read infinity to ground. I always go by the bare vs insulated terminal rather than wire color

To check voltage, turn the key to "run" with engine off. The hot side of the coil and the HEI module should both be same as battery
Click to expand...

Yep, bare on the harness side is ground and bare on the distributor side is positive.
The easy way to remember is that you wouldn't want a bare positive terminal exposed on the harness side in case it grounded against something when not connected to the distributor so positive is the one not exposed. :D
 
TrailBeast said:
It is possible but in my experience close to 008 still runs fine.
It sure sounds like a voltage/amperage supply problem to me, but what do I know?

(RPM's come up, as does the charging system and then the HEI works fine, right?)
Could be, so I would check the voltage with the car running at idle and see what I have.
Click to expand...

Yes exactly! I'll check the voltage. Thanks
 
67Dart273 said:
There is no ground in a Mopar pickup. In fact either wire should read infinity to ground. I always go by the bare vs insulated terminal rather than wire color

To check voltage, turn the key to "run" with engine off. The hot side of the coil and the HEI module should both be same as battery
Click to expand...

Your right , i forgot about that, they should both read infinity, otherwise the pickup would be bad,
 
If wiring with your own double-bullet connector (post #12), check it is compatible. Appliance connectors usually aren't and I had 2 Mopar replacement pickups and one had an appliance type which didn't make secure contact (male pin too short). I expect the OP used the factory one so is OK.

The best way to check pickup phasing is to remove the distributor w/ cap off and coil HV wire to a spark tester. Clamp a timing light on the HV wire and shine it at the reluctor coil as you spin the distributor by hand. You should see the reluctor teeth aligned with the pickup center. If not, reverse the pickup polarity. Judge how powerful the spark is too, relative to youtube videos. It should be able to jump a 1" gap in the air.
 
I haven't had much of a chance to work on it until today... I checked the voltage at the coil, ignition on and it was getting 11-12v. With the engine idling, I was getting 14-15v. The charging system was putting out the same voltage when I checked it while it was running. I also checked the rotor phasing and I had it correct as well. The wiring was correct according to the directions and the wiring diagram I used when I soldered the connectors on.
Could the advance springs be too light for stock teen Ramcharger? I m still using the stock 2bbl LB carb with the mixture plugs drilled out. Could it be jetted so lean that the HEI is causing it to run really lean? Am I tracking this correctly in trying to locate the problem and what to look into next.
Thank you!
 
I would start by making absolutely certain of 'what you have."

Check that the RELUCTOR IS PROPERLY INSTALLED. There are two keyways on the reluctor. The small block must have the pin / keyway installed relative to CW operation

Set the reluctor gap, .008 with a brass feeler. O'Reallys used to have them

Google "rotor phasing" You can see this with an old cap broken or drilled /hacked to see the plug tower contact internally



The pin for CW in this photo must go into the slot in the reluctor up at the top near the pickup

1827249-Distributor_conmod1_crop.jpg
 
I am certain the rotor phasing is correct. CW rotation, checked it to another good known distributor. I did set the gap at .008" using a brass feeler gauge. I do feel positive that is not the problem.
 
How long are the trigger leads from the dist. to the HEI, AKA where is the HEI mounted?

How are the pickup leads "dressed" that is they should be run close to 'ground plane' for shielding.
 
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