Hei conversion troubleshooting

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Maybe this paragraph explains the problem
 
No because I don't know specifically what (module(s) ) it is referring to. There are several on here using the 6 pin modules instead of the older 4 pin, with a Mopar distributor.

Where did you get this text? Link?
 
So I have the points back on the car and I'm tuning it getting ready for my big road trip, and I have an interesting (to me at least) issue with tuning. Under light load, with just a hair of throttle (maybe 1/8 to 1/4") the car runs rough and exhaust pops occasionally. The condition is most pronounced when going around 60-70 cruising with a very light throttle and climbing a slight grade. If I unhook and plug the vacuum advance, it goes away.

So I'm thinking its either too much advance/detonation (dont see any signs on the plugs, and its only at that light throttle setting) OR that its a lean condition just in that one throttle position.

I have initial and mechanical what feels perfect to me, pulls good in 100degree weather with 87 octane and no sign of detonation. Initial is probably around 15. Not sure because I don't have a dial-back timing light and the mark disappears under the water pump anything past 12. The vacuum can on the car adds 27 crank degrees at 15 inches Hg.

I hate to run without vac advance, but i also don't want to compromise how well it runs by dialing back my advance.
I'm also not sure how to richen up the carb (edelbrock 500cfm) for very light cruising throttle.
 
A stronger spring under the rods will richen up the mixture.
But maybe you simply need a one size thinner rod. There's more to it.
Here, an AFR-gauge will tell you what your engine really wants.
 
yeah I know I should do a plug chop but I really really don’t want to go out on the side of the highway in the heat and swap plugs.

I have the Edelbrock manual and have been reading it, but it isn’t really clear on the transition from the idle circuit to the mains, and what percentages each circuit provides at 1/8-1/4 throttle.

Is there an easy way to limit the amount of vacuum advance my can pulls? Stock distributor. A shim or something?
 
If you're lucky, depending on which year, it might have an allen screw inside the can which you can adjust.
 
1967 318 distributor. I’ll go look. That would be nice. The curve in it isn’t completely terrible but it does have a ton of vacuum advance.
 
OK I might have another problem. I just pulled the plugs and the back ones are completely fouled. They are dry, does not appear to be oil fouling, just soot. The rest of the plugs are clean. Why the hell would only the back cylinders foul?
 
My first thought was valve stem seals. Just tore everything down. Stem seals on the worst fouling cylinder (back drivers) were intact and looked good. Car isn’t smoking or burning oil. idk what the hell is causing the back cylinder fouling.
 
smokinnjokin said:
My first thought was valve stem seals. Just tore everything down. Stem seals on the worst fouling cylinder (back drivers) were intact and looked good. Car isn’t smoking or burning oil. idk what the hell is causing the back cylinder fouling.
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Even though its two cylinders I would think the plugs are too cold.
 
OK, update. It was the stem seals, the issue isn't that they are bad, look new actually. The intake seals weren't pushed down over the valve stem boss, but riding up on the valve.

The seals all appear to be new, but the intake (umbrella seal that is supposed to stay down) are too big and are not sticking to the valve guide boss at all. I really hope they are just the wrong ones. I ordered new fel-pro's we will see if they are a tighter fit.
 
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smokinnjokin said:
OK, update. It was the stem seals, the issue isn't that they are bad, look new actually. The intake seals weren't pushed down over the valve stem boss, but riding up on the valve.

The seals all appear to be new, but the intake (umbrella seal that is supposed to stay down) are too big and are not sticking to the valve guide boss at all. I really hope they are just the wrong ones. I ordered new fel-pro's we will see if they are a tighter fit.
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Umbrella seals normally ride up and down with the valve stem.
Change those out for the Viton type that press onto the stem guide castings.
 
I replaced the valve stem seals this morning, and took the car on a 300 mile round trip tuning drive in the 95 degree heat.

I also swapped the step up springs under the rods for the strongest/richest ones (bare metal) it had the middle ones installed. Seemed like it helped my condition a little. Still, with the vacuum advance can plugged in the engine surges slightly and runs rough at light throttle cruising, especially up gentle hills. Unplug the vac advance, runs much better.

I have progressively retarded the initial timing trying to get rid of the bad running condition but I’m at the point now where the car is hard to start.

Now I am wondering if it is somehow ignition related. I replaced the coil, because my original was showing a secondary resistance of only 6.5 K, and the car seemed to run better. Now it seems to be the same. Bad condenser? Or perhaps I fried the new coil in the heat? I am using a ballast resistor.

So here we are, I either have a timing issue, an ignition issue or a fuel issue.
cruising 70-90 mph, car got 11.6mpg with vac advance and 10.6 with it unhooked. 95 degree heat, 87 octane.

I will pull the plugs tonight once the car has cooled off and post a picture of them. And check what initial timing I finally ended up with after retarding multiple times.
 
Here's an update for everyone. After replacing the stem seals from the umbrella-style to the newer press-on style, my problem fouling plugs persisted. As a last ditch, i replaced my (brand new!) ignition coil with yet another and the problem went away. So basically, my stock coil was fried, and the brand new 1.5 ohm accel coil I replaced it with was also bad. Coil #3 did the trick. The coils are mounted in the factory location, horizontally with the factory bracket, with a factory .5 ohm resistor. Apparently they don't make them like they used to.

I have put the stock needle springs back in the carb, reset my idle air mixture and advanced the timing back to where it was. Car is running very well. Hopefully it will make this 1100 mile road trip tomorrow safely. I have a spare coil and all my tools.
 
That was all with the points! Once i get to TX and have time to work HEI again, Going to try a new ignition module (#4) and see if thats the ticket. The brief taste of HEI got, i really liked.
 
smokinnjokin said:
Here's an update for everyone. After replacing the stem seals from the umbrella-style to the newer press-on style, my problem fouling plugs persisted. As a last ditch, i replaced my (brand new!) ignition coil with yet another and the problem went away. So basically, my stock coil was fried, and the brand new 1.5 ohm accel coil I replaced it with was also bad. Coil #3 did the trick. The coils are mounted in the factory location, horizontally with the factory bracket, with a factory .5 ohm resistor. Apparently they don't make them like they used to.

I have put the stock needle springs back in the carb, reset my idle air mixture and advanced the timing back to where it was. Car is running very well. Hopefully it will make this 1100 mile road trip tomorrow safely. I have a spare coil and all my tools.
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Some coils have to be mounted vertically so that the windings are fully submerged in the oil that is in the canister. They fail if you mount them horizontally.
 
dart_68 said:
Some coils have to be mounted vertically so that the windings are fully submerged in the oil that is in the canister. They fail if you mount them horizontally.
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Also, leaving the key on for long periods will fry coils, ballasts, and points. HEI do not draw current when at rest, but points do if closed, and so does the original Mopar ECU
 
I tried the HEI setup on my 71 Duster, had no spark so set it up on the bench and it's sparks no problem. I believe I'm not isolating the ignition 'start' and 'run' leads to trigger the 12v relay. Does anyone know the pin assignments coming off the bulkhead wiring block for both start and run? The mopar wiring schematic shows no switching info for the ignition switch. I don't want to just start cutting wires just to isolate them.

Thanks!
 
I already tried that, the 71 Duster/Valiant wiring diagram doesn't show the ECU electronic ignition. The ignition switch doesn't show individual terminations at the key switch. Nothing shows the function of each wire. I currently have the 4 pin ecu - single ballast resistor setup. Thanks
 
Maybe I’m not understanding it all, but
I think electronic ignition didn’t come out till 72?
GTS Dave said:
I already tried that, the 71 Duster/Valiant wiring diagram doesn't show the ECU electronic ignition.
Thanks
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GTS Dave said:
I already tried that, the 71 Duster/Valiant wiring diagram doesn't show the ECU electronic ignition. The ignition switch doesn't show individual terminations at the key switch. Nothing shows the function of each wire. I currently have the 4 pin ecu - single ballast resistor setup. Thanks
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Easy. Look at your wiring diagram, the ignition switch and bulkhead connector. They normally are called IGN1 and IGN2. The whole deal is, IGN1 is tradtionally "ignition run" and GOES COLD during starting. IGN2 is the coil resistor bypass, often a brown wire, and goes from the igntion switch to the coil+ side of the ballast resistor. It is the ONLY source of igntion voltage during starting, and (normally) supplies the coil during cranking, and "feeds backwards" through the ballast resistor to feed the ECU

If you are bypassing the ballast, those connections must be tied together, then run to feed the ignition system and VR, and on 70/ later cars, the altlernator blue field.

Go to MyMopar and download a service manual I WOULD NOT recomment bypassing the ballast on a Mopar ECU
 
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