Keeping coils cool ..interested in ignition

[Simondo]

Two ways to do the same thing...to mount a coil (ignition module) next to a flywheel to give a spark.
But ...maybe there are other things to take from the designers choices to do with location and to aid the case shape .
The pics show 2 common locations of the 1 piece unit of (many Husq at oil tank end of the case but mostly enclosed) ..saws or many other OPE motors.
I believe we will agree that electronic components need to have some cooling, so do we think ether choice ...may ... have a down or a up ?..for performance and longevity of a coil ?
The red one is somewhat more in the open and the cross saw air flow, where as the black one is having more of a direct blow from the fan off the flywheel as it sits in part of a slight "snail back shape" enclosure.
The red one "possibly" could get more heat soaked after stopping the saw unless you allow a idle to cool things a little where as the black one could be looked upon as more "Heat Shielded " from the cylinder and muffler ..BUT.. can get covered in crap that stays put thus stopping the best cooling from the fan.
Cooling and not allowing heat soaking of a motor is paramount ....and so i would say it is the same for the electronics involved.
What say you ........

 

[Sleeper]

Well, as long as it's mounted where it won't collect sawdust and oil in a short run time, it's good.

The Pro Mac 605/610/650 is notorious for coils getting covered in crud and either making hot starts not possible or killing the coil altogether...

 

[Wilhelm]

I don't like the red coils placement, I think it is too close to the cylinder.

But that's just a random opinion!

 

[Simondo]

I don't like the red coils placement, I think it is too close to the cylinder.

But that's just a random opinion!

Opinions and reasons are just what I posted this question to get

 

[Wilhelm]

Regarding the red coil placement.

I'm thinking, how much heat will transfer from the cylinder over to the coil once the saw gets shut down after a hard run.

 

[Simondo]

Regarding the red coil placement.

I'm thinking, how much heat will transfer from the cylinder over to the coil once the saw gets shut down after a hard run.

They do have heat isolators on the bolts, but just shutting off after being run would leave things good and hot. At least the cylinder by its design has cooling fins to radiate heat away unlike a larger mass of a Mag case. A short idle before shut down is what i do ..always ..whatever the saw.

 

[Simondo]

Regarding the red coil placement.

I'm thinking, how much heat will transfer from the cylinder over to the coil once the saw gets shut down after a hard run.

I have invested in a hand held infrared thermometer to give me a indication of how fast things cool down from run temp along with other conditions and repair tasks.

 

[Al Smith]

I could never figure out why in the name of good sense Husqvarna had the coil inside the flywheel on the model 2100 . I would have thought it would cool better if it were in the fan blast .

 

[Simondo]

I could never figure out why in the name of good sense Husqvarna had the coil inside the flywheel on the model 2100 . I would have thought it would cool better if it were in the fan blast .

Do you know if the ignition was reputed to gave much agro on the 2100 Al ?

 

[Al Smith]

I don't even know what agro is .If it's aggravation it would be me .The 2100 I have spend a number of years on a barn floor on some island off of Washington state with a bad coil .Damned coils cost nearly 200 bucks .
Sooo I got a used one from good ole Bryce for 50 bucks but the kill wire didn't work .So I spliced in a 100 thousand volt ignition wire from the plug wire to a kill switch .Problem solved but it was still aggravation .
While on the subject FWIW inside coils are not new .Wico systems on some small engines used them as well as many outboard boat motors .Of course an outboard is water cooled .
The heat most likely would have very little effect on the actual coil but it could have on the internal solid state trigger circuitry taking place of a points type ignition .

 

[Simondo]

I don't even know what agro is .If it's aggravation it would be me .The 2100 I have spend a number of years on a barn floor on some island off of Washington state with a bad coil .Damned coils cost nearly 200 bucks .
Sooo I got a used one from good ole Bryce for 50 bucks but the kill wire didn't work .So I spliced in a 100 thousand volt ignition wire from the plug wire to a kill switch .Problem solved but it was still aggravation .
While on the subject FWIW inside coils are not new .Wico systems on some small engines used them as well as many outboard boat motors .Of course an outboard is water cooled .
The heat most likely would have very little effect on the actual coil but it could have on the internal solid state trigger circuitry taking place of a points type ignition .

Yes i shortened aggravation to agro...

 

[7sleeper]

... A short idle before shut down is what i do ..always ..whatever the saw.

Same here, I let it idle as long as it takes to take off protective equipment (helmet, eye & ear protection, etc.).

7

 

[Al Smith]

After being rather frustrated with a couple of McCullochs I learned to do a cool down myself .If not the damned things would not start for twenty minutes .Then again that might have had something to do with sawdust clogged fins etc ---duh .

 

[Simondo]

After being rather frustrated with a couple of McCullochs I learned to do a cool down myself .If not the damned things would not start for twenty minutes .Then again that might have had something to do with sawdust clogged fins etc ---duh .

I pull up in my car and never just dump the key ether , always a good thing with a TDi anyhow (turbo lube ). I figure with some saws having a micro computer (of sorts) in the ignition it has to be prudent to allow some air to get pulled/pushed over the motor without a load on it before shut down.

 

[Al Smith]

Depends on the coil .Some work off the detection of a negative dip in the sine wave to fire,some will self advance .You could have mix of transistor switching ,thyristers and a whole host of components of which you'll never know because they don't advertise how they are built .The bottom line is with enough heat they will fail .In some cases they go to full advance and you'l never get them started until they cool off .Briggs coils are notorious for that .I think they are called Magnitron .
Of all the printed material I have,which is a lot ,the only pictorial representation and explanation of is the self advancing coils ,SEM,used on the 042 and 048 .So it must be half-fast top secret .Really doesn't make a difference you can't repair them any way .

 

[Dub11]

I have invested in a hand held infrared thermometer to give me a indication of how fast things cool down from run temp along with other conditions and repair tasks.

I have found through years at my job those infrared temp guns work best when collecting data off a flat black colored surface. Shiny surfaces will give a bad reading and the closer the better for temperature readings.

 

[Simondo]

Depends on the coil .Some work off the detection of a negative dip in the sine wave to fire,some will self advance .You could have mix of transistor switching ,thyristers and a whole host of components of which you'll never know because they don't advertise how they are built .The bottom line is with enough heat they will fail .In some cases they go to full advance and you'l never get them started until they cool off .Briggs coils are notorious for that .I think they are called Magnitron .
Of all the printed material I have,which is a lot ,the only pictorial representation and explanation of is the self advancing coils ,SEM,used on the 042 and 048 .So it must be half-fast top secret .Really doesn't make a difference you can't repair them any way .

I have had a few Magnitron units that were within there supposed Ohms range give out once the motor warmed up. Thankfully its a quick thing to swap out and there available for most engines still.

 

[Simondo]

I have found through years at my job those infrared temp guns work best when collecting data off a flat black colored surface. Shiny surfaces will give a bad reading and the closer the better for temperature readings.

I made sure the one i got had "Emissivity" settings...That should help ??. Handy things and not just in the workshop .