Napa Part No. Echlin MO-3000

[TrailBeast]

I went to the local Napa Auto Parts store today and asked for this part number, and the guy said "Hm, I don't ever remember selling that part number and I've been doing this for 45 years."
When he looked it up and saw the part, he said it looked like a Dodge, Chrysler, Plymouth rotor and wondered why it was a different part number than he's ever seen before.
I told him that the brass piece on this rotor was .060 longer than the stock rotor and he looked at me weird and said "What? What possible reason would anyone need a rotor with a longer arm on it?"
I explained to him that when you install a GM HEI ignition system using the Mopar factory electronic distributor that you should replace the original with this one to keep the arching across the contacts to a minimum so they burn less and it helps to keep the spark from jumping to places it does'nt belong.
He says "How is it that you know about this?" and I told him most of the information came from FABO and Daniel Stern and that all the good stuff about Mopar A body cars comes from FABO.
He says he has heard the Stern name before, but didn't know who he was and that he was going to have to chk out our site.

Maybe he will, maybe he won't, but it sure was fun to stump a 45 year Napa veteran with his own part numbers.

 

[bguihan]

I got the same look at the NAPA store in Douglas. He didn't think that it would make that much of a difference.

 

[Oklacarcollecto]

So without this rotor the HEI modification ends up doing what in the long run?

 

[67Dart273]

It used to be a well know fact that GM V8 rotors (back in the "points" days) were two different lengths. I was told by a Champion spark plug guy that GM actually SHORTENED the rotor to act as a "spark intensifier." He claimed the champion "booster gap" plugs (the old "U" series) came out first, and "GM screwed Champion" by coming out with the short rotor.

(I see Champion has somewhat re-introduced this idea for small engines with their "EZ start" or "One pull" plugs.)

So who knows? Without a bunch of testing, it might just be counterproductive.

 

[kursplat]

older mopar racing manuals used to have instructions to file rotor end to a point so the spark would have a nice sharp point to jump from :burnout:

the one i had was early 70's and yellow cover. looked like a phone book...let me know if i need to explain "phone book" to any of you kids :glasses7:

hey TrailBeast, have you run this before? i've seen a few where the cap was maybe on the tight side of spec or the distributor was worn and it caused some, let's say havoc, inside the cap

 

[3404speed]

Hei works fine without this rotor.

 

[TrailBeast]

So without this rotor the HEI modification ends up doing what in the long run?

Over time with a stock rotor it will arch burn the rotor tip and distributor terminals more.
It will work fine without it though too. (just a slight chance the spark might go somewhere else, like through the rotor to the distributor shaft)

Over time, those parts get worn out anyway.

 

[TrailBeast]

older mopar racing manuals used to have instructions to file rotor end to a point so the spark would have a nice sharp point to jump from :burnout:

the one i had was early 70's and yellow cover. looked like a phone book...let me know if i need to explain "phone book" to any of you kids :glasses7:

hey TrailBeast, have you run this before? i've seen a few where the cap was maybe on the tight side of spec or the distributor was worn and it caused some, let's say havoc, inside the cap

Some caps are not machined straight brand new (Like the MSD's) and the rotor will sometimes rip the cap right off on the first crank over.
I pulled my dist when I installed mine, then turned it by hand to make sure it cleared.

 

[3404speed]

I bought on of the rotors, and tested it on my slant distributor off the engine, placed the Mo40 on it and the rotor hit. As slantsixdan noted, the caps were not precision ground. He notes that the Cap: Standard-Bluestreak CH-410X is much better. Haven't bought it yet.

 

[67Dart273]

LOL. Model T's were one of the first individual coil ignition. Now we've come full circle!!!

 

[tekslk]

Ive used the hei with this rotor for 2 weeks now and couldnt be happier, especially on a hot restart.

 

[TrailBeast]

Ive used the hei with this rotor for 2 weeks now and couldnt be happier, especially on a hot restart.

I'm running one also, and it works fine for why it is there.
Ya have to buy a new rotor once in awhile anyway, right?
And then there's the point Del made earlier about some early ignitions used that gap as a "spark intensifier" so who really knows for sure.
Doubt it would matter much with the HEI spark anyway.