372 Unlimited Coil?

[beaglebriar]

I’ve gotten one bad one over the years out of 20-30.

I bought a 2159 real cheap because of a bad coil. It is kinda rare though.

 

[XP_Slinger]

I'll take that 346 coil off your hands. [emoji16]

Not mine, borrowed a pic. But if it were I’d keep it

 

[Steve]

You gonna take this thing racin Steve?

You never know John!


Just soaking up some information.

 

[XP_Slinger]

You never know John!


Just soaking up some information.

Black coil it is then

 

[old guy]

I have a blue on a 372 that's marked 13100.

 

[Onan18]

I have a blue on a 372 that's marked 13100.

Most of the later 372 XT came with the 13,100 coil.

The P/N for the 372 unlimited coil is 544 04 71-01, suggested retail is $84.99 as of 01/2020. You can use a black coil off of a smaller saw (346/455/etc...) but it doesn't match the curvature of the flywheel well and can be difficult to set the air gap.

 

[old guy]

It's on an OE saw so it must have been changed, saw runs strong so I didn't change the coil.
I have 2 of those unlimited coils from HL, $84 each, & one from a junk 350 so I have coils.
I only put a tach on a saw after tuneing to see where it's at or I lean it to the rev limiter with the tach then lean it from there till it cuts best.

 

[mdavlee]

Almost all the 372s I ever ported tunes low 14k and we’re plenty rich there. Some would go 16k or so with a slight 4 stroke

 

[old guy]

I bought a well used stock OE 372 a few years ago. shortly after that I bought a tach. That saw was crankin 14600, when I tried to slow it down the screw was allready against the limiter, so I guess it ran that way all it's life.

 

[mdavlee]

I did have one coil that had way more advance or something in it. It was good for 5% faster cuts swapping the coil only[emoji2371] I had to drill the holes to mount it on a 372. I never understood why or what it came from either. I should have kept it but I let it go on another 372 I sold

 

[Duane(Pa)]

From a 2000 catalog...

 

[Lightning Performance]

I'll take that 346 coil off your hands. [emoji16]

hoeder

I have a blue on a 372 that's marked 13100.

Anything around 13 seems good for work saws. Most seem to perform best near the limiter so I follow along most times and tune right there near jingle bells

I did have one coil that had way more advance or something in it. It was good for 5% faster cuts swapping the coil only[emoji2371] I had to drill the holes to mount it on a 372. I never understood why or what it came from either. I should have kept it but I let it go on another 372 I sold

Coils with retard up top do a little better with a fast chain imo.

That's a cool bit about the midrange advance.

 

[legdelimber]

I'm just bored and mildly curious.... so the answer aint that big of a deal.
How the did the ignition know when "the saw comes under load"?
Manifold vacuum or was it like the auto-tronic stuff and compared rpm to throttle position?

 

[huskyboy]

The blue coils definitely have an advance around 3,000-3,400rpm. If you tune the idle too high on the saw it can be erratic from it going in and out of advance. I had a 385/390 I advanced the timing with a 13,300 coil a bit too much and the saw popped when it got hot. Swapped a black unlimited on it, did not touch the timing key... popping gone. Black coil seems to have a fixed advance curve and less of it too.

 

[Duane(Pa)]

I'm just bored and mildly curious.... so the answer aint that big of a deal.
How the did the ignition know when "the saw comes under load"?
Manifold vacuum or was it like the auto-tronic stuff and compared rpm to throttle position?

This is just a guess... There’s no wires or sensors on anything...(back then) has to be strictly RPM. Again, only a guess

 

[CJ Brown]

I'm just bored and mildly curious.... so the answer aint that big of a deal.
How the did the ignition know when "the saw comes under load"?
Manifold vacuum or was it like the auto-tronic stuff and compared rpm to throttle position?

IMHO as load increases on the saw, so does cylinder pressure. As cylinder pressure rises, so does resistance between the spark plug gap. The coil can sense the extra electrical resistance and adjust the timing.