Coil Confusion

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I have a brand new Napa part number ICR11 resistor in my hand that measures 1.4 Ohms.
I just installed it and i'm reading 8.8 volts at the coil while idling
I am going to order another ECU as a back up.
 
The ICR11 resistor is a poor choice; the 1.4 ohms cold will end up being 5 ohms or more hot and will cut your spark energy. It is the wrong part for a stock based Mopar ignition system..

Go to Advance or OtterZone or similar and find a BWD RU19; that will be a bit above 0.5 ohms cold and 2.5-3 ohms hot. And, I would encourage you to find an NOS ballast on eBay; PN 2095501 is 0.5-0.6 ohms cold and around 2 ohms hot.

I would do as you plan and get another ECU; but eventually would try to find an NOS ECU. The newer ones from the stores are not noted for their reliability. (BTW, some of the coil heat is likely due to the orange box; I understand they have extra dwell to support higher RPM use.)

Clean up you wires and all contacts and connections and check your reluctor gap with a non-ferrous gapping tool. I would suspect an erratic connection or part for the latest stall.
 
nm9stheham said:
The ICR11 resistor is a poor choice; the 1.4 ohms cold will end up being 5 ohms or more hot and will cut your spark energy. It is the wrong part for a stock based Mopar ignition system..

Go to Advance or OtterZone or similar and find a BWD RU19; that will be a bit above 0.5 ohms cold and 2.5-3 ohms hot. And, I would encourage you to find a NOS ballast on eBay; PN 2095501 is 0.5-0.6 ohms cold and around 2 ohms hot.

I would do as you plan and get another ECU; but eventually would try to find an NOS ECU. The newer ones from the stores are not noted for their reliability. (BTW, some of the coil heat is likely due to the orange box; I understand they have extra dwell to support higher RPM use.)

Clean up you wires and all contacts and connections and check your reluctor gap with a non-ferrous gapping tool. I would suspect an erratic connection or part for the latest stall.
Click to expand...
It's funny you mention an NOS resistor. I noticed a while back the PO left the OE resistor installed and added the new .9 ohm just above it. I just measured the OE resistor and it's at .6 ohm cold. Perhaps I should just go back to using that one?

I'll look into getting the BWDRU19 you mentioned.
If I do get a backup ECU, should I stick with orange or just go with basic black?



Thanks
Danny
 
That IS interesting. Perhaps the OE did not realize that any ballast resistor will increase in resistance when hot, but probably he was trying you compensate for the low coil resistance of the Accel to keep it cool. Silly, because that just reduced coil spark energy and took away any advantage of the Accel.

I have sorta lost track here; you replaced the Accel coil with a 1.5 ohm stock type coil, is that correct? (I.e., the Duralast Gold is a 1.5 ohm primary resistance coil?) If so, I would go back to the OEM resistor and use the RU19 as a back up. If the coil still gets too hot, then I would look at more cooling and the orange box.

If you are just running this car on the street, I would go back to the regular plain-Jane OEM ECU box. There is no need for any extended dwell time for lower RPM street use.

And you may want to read up on HEI conversions and see if that is for you. It may be, as it sounds like perhaps your son is happy to be an 'equipment operator' at this point in time, and it may make life simpler for you. I keep the stock stuff because I am interested all-original operation, but it has the limitations of 60-70 year old technology.
 
nm9stheham said:
That IS interesting. Perhaps the OE did not realize that any ballast resistor will increase in resistance when hot, but probably he was trying you compensate for the low coil resistance of the Accel to keep it cool. Silly, because that just reduced coil spark energy and took away any advantage of the Accel.

I have sorta lost track here; you replaced the Accel coil with a 1.5 ohm stock type coil, is that correct? (I.e., the Duralast Gold is a 1.5 ohm primary resistance coil?) If so, I would go back to the OEM resistor and use the RU19 as a back up. If the coil still gets too hot, then I would look at more cooling and the orange box.

If you are just running this car on the street, I would go back to the regular plain-Jane OEM ECU box. There is no need for any extended dwell time for lower RPM street use.

And you may want to read up on HEI conversions and see if that is for you. It may be, as it sounds like perhaps your son is happy to be an 'equipment operator' at this point in time, and it may make life simpler for you. I keep the stock stuff because I am interested all-original operation, but it has the limitations of 60-70 year old technology.
Click to expand...
Original coil when purchased was an MSD Blaster. I have since put in a duralast gold stock-type. One of the previous members had mentioned they run an Accel coil.
I have been reading about the HEI and it does look tempting, and way cheaper than an MSD box.
 
OK, I got confused on the original coil. The new coil you have is 1.5 ohms so you can set the ballast as described.
 
Sounds like it is frustrating you, and family pressure doesn't help. One easy thing to check is that you have a good ground on the case of the ECU (not rusty sheet-metal screw).

The coil shouldn't be too hot to touch. I have one small data point. I hot-wired my 64 Valiant (points) to drive home after buying. Initially, I jumped 12 V straight to coil+. It ran OK until the coil got too hot (paint smelling), which I found when it started missing ~40 mph. I then jumped thru the ballast and no more problems. When real hot, it idled OK, but missed at higher cylinder pressure (more throttle).

I am not sure an e-core coil will help. As I understand, the ballast is needed because these early electronics could not control dwell current as later designs can (GM HEI, Ford TFI, ...), but read Kit Carlson's posts for more info and O-scope views.

Don't throw in the towel. Worst-case, you could buy the $45 ready-to-run HEI distributor on ebay and toss the ballast. Add an e-core coil ($20) and you will be sparking strong.
 
BillGrissom said:
Don't throw in the towel. Worst-case, you could buy the $45 ready-to-run HEI distributor on eBay and toss the ballast. Add an e-core coil ($20) and you will be sparking strong.
Click to expand...

Wow, I didn't know you could get HEI distributors so cheap (hope they are good). I'm still researching and reading about HEI and it is way cheaper than an MSD box. I like the E-core coil idea but I think I read there are 2 kinds, one for CD ignition and the other is not.
The family pressure is not bad. My boy is very patient and appreciative. He sees me sitting at the computer for hours reading up on his car. I kind of welcome the occasional "issue". It keeps me on my toes and always, always increases my knowledge.
 
FWIW..... E-cores are nothing magic; they are another form of coil and were being used before HEI ever showed up. The late 60's and 70's Opel use e-core coils with the old points distributor type of system and no ballast. The coil primary resistance was high enough by itself (approx 3.5 ohms).

"As I understand, the ballast is needed because these early electronics could not control dwell current as later designs can "

That is right; as the coil primary resistance is made lower so the coil can draw more current to build up more spark energy, then the coil can draw too much current on the long dwell periods that occur at low RPM or idle operation. The ballast varies its resistance to compensate that to some degree. It is a compromise and balancing act to get it right.

Part of the orange box/chrome box/gold box strategy is to extend the dwell so that there will still be sufficient time to build up a good coil charge at the shorter and shorter dwell times available at higher RPMs. But that causes higher average current draw at low RPM and idle. That is why there are warnings with some of the higher RPM boxes and associated coils/ballasts to not operate them for extended periods of time at below certain RPM's.
 
OK. so Monday, my son's car stalled and he was stuck halfway in a gas station for a few minutes until it started again. On impulse, I ordered an MSD 6AL and blaster coil from summit. Later that day, I had gone to pick up his car and drove it home. All was OK until I started pulling the final hill to my house and it stalled. Once in the driveway, the mailman showed up with the replacement blue Standard ECU I had already ordered previously in the week. I promptly installed the blue box and shelved the orange box for now. I also moved my ballast wires back the OE ballast that I had previously measured .5 ohms.
Tuesday, no issues for my son. (MSD goodies arrived too)
Wednesday, no issues for my son.
I'm going to give it a few more days and see how things go. In the meantime, I have done some more reading on the HEI conversion and think that if I have any more issues with my son's car, I may step up to HEI.
Looks like it's an early "MSD" Christmas for my 'cuda. lol
I appreciate everyone's input. I'm hoping stepping down from the orange ECU will be the ticket.
 
That is good to hear... You have to wonder if it is the orange box per se, but just THAT particular orange box has gotten flakey. Standard boxes fail too. IMO, that orange box needs a permanent home in the dump!

Is the coil any cooler now?
 
The coil still seemed a bit hot on Tuesday, and I forgot to check it today. I'll keep an eye on it, though.
 
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