Rewiring 1971 Demon question

[LuckyJackson]

A question for those experienced in these matters (273 Dart/Trailbeast). I am converting from older HEI (MSG) to Chrysler ignition. Removed all old engine wiring that was rigged for many years. Installed new Year One engine wiring harness made for ECU unit. New ECU/4 prong ballast/Coil. Things hooked up pretty easy. I don't know if I need to change the distributer that was being used with HEI system. I'm in the process of checking/testing everything but I don't know if this distributer will work with ECU system. I am putting 12 volts to positive side of coil, but no spark. Tried several coils...no spark. Before I go through 273Dart's testing procedure.....Am I an idiot trying to use the HEI (MSG) distributer? Can't find anything that says they're compatible/incompatible. Can someone give me a definitive answer? Thanks.

 

[67Dart273]

What is an HEI MSG?? You mean MSD? If this is one of those unitized ones with the module inside, yeah, you need a stock like Mopar dist,

If you are "handy" you might be able to get into the dist you have and bring out just the trigger wires, if they are magnetic. Two wire, not three

 

[LuckyJackson]

Haha. Yea Told you I was an idiot. MSD! I'm not that handy and I have no attachment to this old distributer so it's not worth it for me to try. I have no problem getting rid of the prior owners junk. Can I get a brand recommendation for a decent Mopar distributer? Will I get a piece of garbage from Advanced Auto and such places?

 

[Big.J.007]

@halifaxhops is the guy if you want a good distributor

 

[4eighteener]

You could use the distributor blueprint engines uses on theirs. Good quality, good price.
Contact @Johnny Mac

 

[Johnny Mac]

A question for those experienced in these matters (273 Dart/Trailbeast). I am converting from older HEI (MSG) to Chrysler ignition. Removed all old engine wiring that was rigged for many years. Installed new Year One engine wiring harness made for ECU unit. New ECU/4 prong ballast/Coil. Things hooked up pretty easy. I don't know if I need to change the distributer that was being used with HEI system. I'm in the process of checking/testing everything but I don't know if this distributer will work with ECU system. I am putting 12 volts to positive side of coil, but no spark. Tried several coils...no spark. Before I go through 273Dart's testing procedure.....Am I an idiot trying to use the HEI (MSG) distributer? Can't find anything that says they're compatible/incompatible. Can someone give me a definitive answer? Thanks.

You could use the distributor blueprint engines uses on theirs. Good quality, good price.
Contact @Johnny Mac

Thanks for the tag 4eighteener,

Sounds like op has a dead msd "ready to run" or it's not wired correctly.

Your 2 options with us are another pro billet type that is a ready to run, and has the ecu module inside (only needs a 12v, and doesnt use the Chrysler ecu at all. Or a 2 wire, which you hook up as you would an oem distributor. Links below, in that order.

Typically I don't like the oem Chrysler setup because the aftermarket ecu's are junk, and once a stock one goes, you are at the mercy of cheap replacements.

We sell all the replacement parts for our distributors, as does msd. So can even buy a spare module for the glove box.

self sustaining
Chrysler 273-360 c.i. SB Compatible ProSeries Ready to Run Distributor - Black Cap

2 wire
Chrysler 273-360 c.i. SB Compatible ProSeries 2-Wire Distributor - Black Cap

 

[Demonx2]

If he's already got the ECU and a stock new harness, and it's not for a race car, I would use one like this. (I'm assuming the car has an LA V8 since its a 71 Demon) I would want some vacuum advance for the street and improved fuel economy.

 

[4eighteener]

I like the male terminal caps of the blueprint model better. Depends on the wire he currently has if trying to re-use them

 

[Johnny Mac]

I like the male terminal caps of the blueprint model better. Depends on the wire he currently has if trying to re-use them

I agree, at worst a set of plug wires, or Even new terminal ends isn't much to deal with. Just because mopar let's someone license the name, doesn't make that distributor any good. Ours is completely tunable. But the 2 wire model does not have a vac advance. The ready to run 3 wire does.

HOWEVER... alot of aftermarket distributors have WAYYY to long of an advance slot, or aren't adjustable at all (no hex screw in the advance)
We actually made tooling to limit the amount of vacuum advance a canister can add.

 

[LuckyJackson]

Thanks everyone for the info. When 67Dart mentioned 3 verses 2 wires out of the distributor I took a longer look at it today.....It sure looks like a Mopar distributor. It has a plate to with a number 3656763. Part #? Took some pics. If it is a Mopar, it was used in the old MSD system, and it should be ok for me to use in the Mopar ECU system. Can someone verify this for me by the photos? Thanks. I made sure the module had a good ground, grinded the inner fender to bare metal, and added a direct wire to the neg. on battery. No spark. Only getting 6 volts to the module from the baby blue wire to the top point of the connector from the Ballast Resister (4 prong type). It seems the module is working because that 6 volts is coming out at the pins and going to the distributor. But that's clearly not enough voltage to fire the plugs. Could my problem be that I have no dash wiring? Only put in new engine harness and I am taking 12 volts from the fusible link prong on the push in box and jumping it to coil +? Then I use a push button jumper on the relay to engage starter motor. Good crank, no/weak spark. I have 12 volts at the brown wires at the BR. The other side of BR goes down to 6 volts.....and that's what is going to the module. Does Reversing the BR change anything? I wouldn't think so, but I've yet to try. I also tried 3 coils and have had no change. Am i bypassing the ignition correctly? Any help is appreciated.

 

[67Dart273]

When you connect the Mopar box to MSD do not assume. Look up (search) "rotor phasing." If the Mopar wires and MSD pickup wires are reversed you will have phasing problems and it will not run right. Normally, carefully following MSD vs Mopar color code connections will be correct.

Be sure to look the Mopar dist over carefully, read the service manual (Get a 72 or 73 from MyMopar.com for the electronic ignition info) check the dist for bent shaft, worn bushings or worn advance mechanism. Check the pickup gap with a brass feeler gauge. Double check I think it is .008" that is inches, not metric.

Look over the core of the pickup and the reluctor for rust, stuck on debri, or "strike damage" from hitting each other. Do not round off the reluctor sharp corners, but you can carefully sand off the rust on the surface.

Also if you are going to re-use the Mopar pickup coil connector, be aware that there is almost no current through there, and the terminals can become corroded. "Work" the mate connector in/ out several times to "feel" for tightness and to scrub the terminals. Check with your ohmeter clipped to the mating connector and wiggle test for poor conntection, IE continuity between the connector.

I have fought several cases of iintermittent spark because of that connector

 

[LuckyJackson]

Thanks for the suggestions. Took the weekend off from playing with it. Going to try again today. I don't know why Year One sent a four prong module with a double ballast resister set up harness. Makes it kind of difficult to understand. So there shouldn't be 12 volts coming out of BR. Is 6 volts going into module and then out to distributor correct? The ECU doesn't increase voltage, correct? I will take a closer look at the internals of distributor, clean the terminals and try to find brass gauge. What position should it be in for measurement? Shouldn't I get a spark if I ground the two way distributor connection from the module? I get none. Thanks again.

 

[67Dart273]

The 4 prong ballast harness is needed for the older FIVE terminal ECU, but it will work with the newer FOUR terminal ECU. You can connect a 4 pin ballast, it's just that one of the two resistors are not used.

Maybe this will help. The COIL side of the ballast / coil circuit is wired the same for breaker points, for newer 4 pin ECU, or for older 5 pin ECU. The second half of the ballast feeds dropped voltage to the ECU for PART of the circuit, no longer used

YOU CAN NOT TELL if an ECU is 4 or 5 pin by looking, because some newer 4 pin boxes actually HAVE 5 physical pins. You are VERY unlikely to run into a new 5 pin box unless you happen on some (very) old new stock.

NOTE THAT MANY diagrams are WRONG or incomplete. This diagram is OK EXCEPT the upper terminal of the ballast DOES NOT CONNECT to "S start." The ign2 terminal of the ignition switch is the bypass circuit, normally brown, and COMES LIVE in START just like the "S" start contact does but IS A SEPARATE switch contact to prevent backfeed.

IF YOU incorrectly connect that terminal to "S" as shown, then on older stick cars with grounded start relay, the circuit will backfeed power from the coil + to the start relay, and try and keep the starter engaged, as well as loading down the voltage at the coil.

One a 5 pin ECU, the second resistor takes ignition switch 12V from "R run" through the second resistor, and feeds it to the 5th pin (green) in the diagram. This part of the ECU circuit was changed in the 4 pin modules

On a side note, as I mentioned, the breaker points ballast/ coil wiring is the same. If you have a breaker points resistor, and the ECU quits, you can just unhook the box connector, install the breaker points dist. and wire the dist wire to the coil neg, set the timing, and be off. The ballast / coil wiring is unchanged

 

[LuckyJackson]

Took some time and sanded the reluctor with some 350 grit. Got most of the surface rust off. Improved some grounds and cleaned the distributor pigtail with some battery terminal cleaner. Replaced the ECU from Year One with one I had gotten from a guy who sold me his 1969 383 from his charger. Looked at it and the thing is made in USA. It fired up. Thanks 67Dart, J.Mac and everyone. I will have more problems/questions as I attempt to put the dash Harness/bezel/Ignition in. If anyone knows where I can get key cylinders please give me a heads up. Thanks again.