Mechanical voltage regs and electronic ignition systems

[FURYGT]

Ross, what is the amp rating of the alternator in your car? Your photos would not load for me. Do you have a traditional Mopar alternator or one of the Leece Neville models that many police cars had?

 

[Davea Lux]

Leece Neville alternators were available with several different pulley sizes, might be able to go to a smaller pulley to get rid of the dead spot at idle.

Dave

 

[Ross Wooldridge]

I don't have a Leece Neville at this point. I'm running a year correct traditional roundback regular unit that's set to output 60 amps, with the slightly smaller diameter drive pulley as has been suggested.

I'd like to get a Leece Neville, but I don't know for sure if it's correct for my car nor do I know if it uses the same mounting bracketry etc... I suspect it would be hard to find that stuff it's it's so.

 

[FURYGT]

What electronic items are you running? I know that on the early '70's C Body police cars with Leece Neville alternators used special brackets. Check you parts book on the brackets.

 

[Ross Wooldridge]

I'm going to look into it a bit...

 

[Ross Wooldridge]

So upon looking at my parts book, the Leece Neville alternator has totally different brackets. My car has never shown me any evidence that the brackets were different than what one gets with a traditional alternator. The book also shows that there is a heavy duty traditional alternator that puts out 1 amp less than a Leece Neville - 59 amps as opposed to the LN's 60 amps.

Being my car has all the other police heavy duty charging stuff (adjustable Vreg, special regulator bracket mounting bracket on the inner fender, police wiring to the amp gauge etc), I suspect my car originally had the 59 amp HD traditional alternator, and as I write this, the greybeard that has rebuilt various alternators for me over the years used all the HD guts in the rebuilding of the one I have on both my wagon and the Monaco now.

So, I'm not going to go down the rabbit hole of sourcing a Leece Neville setup. I will however still investigate isolating the ECU from damaging noise created by the mechanical Vreg so I can use the correct one. If it can't be done, I'll go back to points!!

Interestingly, the parts book also shows a solid state transistorized Vreg, part # 2642596

I wonder if anyone has one of those kicking around?!

 

[Ross Wooldridge]

Ross Wooldridge said:

"Could I wire the ECM to a battery feed and bypass the VR/Alternator to achieve the required constant voltage source?"

Powering the ECU from battery voltage through a relay should help because it won't be on the same circuit as the Vreg, and the battery will help to filter any noise injected onto the power rail. Do not connect the Vreg through a relay though. You want the Vreg sense voltage to be the same as most of the car's electrical systems see, so that it regulates effectively.

I realize I confused things when I talked about powering the ECU from a relay controlled battery feed - I did not want to also power the Vreg the same way as it would render its' function near useless... just the ECU to give it clean constant power. I mistakenly said Vreg instead of ECU in the latter 1/2 of the question regarding the use of a relay. Ultimately though, the idea of powering the ECU from a direct battery source through a key operated relay seems to have met with a fairly positive response... so finding ways to eliminate the noise created by the Vreg is the other task.

 

[Ross Wooldridge]

Update: I have confirmed from an unusual code on my fender tag that my car came with the 59 amp round back alternator, and NOT Leece-Neville, so I can rest easy that my car has the right stuff on it.

Thanks everyone for their help and interest, and for @Bill Watson for decoding my tag. Interesting stuff on there, which confirms a number of things I already knew about my car.