how hot is stock coil?

[tejope]

Got a 606 gas w/ loader. Does a lot of around the yard work, but when I put it in the field, it falls flat on it's face and I gotta clean plugs first. Always been suspicious of the coil, thinking about putting on a hotter one, like the Petronix 40k volt. Anybody know what the voltage of the stock coil is? Would a hotter coil and wider plug gaps help this plug fouling problem?

 

[Janicholson]

Spark voltage is always a function of the total resistance of the coil wire/rotor/rotor to cap gap/wires to plugs, plug internal resistance, and gap. It is very rare that voltage required to fire these combined resistances exceed 20,000 volts. The coil's reserve capacity above that 20K is OK, but no where near 40K. The amount of current flowing through the switch system (points/condenser, or electronic timing system) is going to be around the 4 amp level with most (usable) coils.
The issue is either both or one of these:
Carb richness may be set too high for light work causing deposits on the plugs
The plugs may be too cold allowing deposits to build up even when just right.
Adjust the carb leaner, and or use hotter plugs for light work, and colder plugs for tillage or heavy shaft work. JimN

 

[Bob M]

Will a hotter coil solve the problem? Probably not…

If cleaning or replacing plugs temporarily cures the misfire, the problem is not likely the coil. In fact installing a “high voltage” coil may even make it worse.

Suggest rather you look at the following:

Spark plugs’ heat range is too cold. Switch to plugs 1 – 2 heat ranges hotter than what the manual suggests. (Note: This is a common problem when you combine extended operation under light load - the “yard work” you mention - with the poor quality gasoline we’re stuck with today.)

Carburetor is set too rich. If you see any trace of black in the exhaust – especially at idle - it’s too rich!

If you use the choke to start the cold engine, get the choke opened and the engine under load as quick as possible. (Excessive choking on a cold engine fouls plugs VERY quickly…)

Make sure the engine’s thermostat is present and working. A cold engine lightly loaded tends to foul plugs.

 

[John T]

I agree with my friends below n heres my two cents worth. The actual voltage at which the stock coil or an expensive high voltage after market coil fires GIVEN THE SAME CONDITIONS is the sameeeeeeeeeee...... Its just that the HV coil has the CAPACITY to ramp up to a higher voltage (to fire a wider plug gap) then a stock coil would butttttttt still it only reaches a high enough voltage to fire the plug n no more REGARDLESS of a higher voltage rating. If the gap is too wide a stock coil may not fire it like the HV coil could.

The voltage at which a plug fires (among other things) is a function of the medium (fuel and compression) in which it fires PLUS the plug gap distance i.e. why a stock coil could fire at same voltage as a HV coil.

Nowwwwww that being said, to gain much in performance you would use a high energy high voltage coil and couple it up with an electronic ignition switch (to replace points) and then run that wider plug gap you mentioned AND END UP WITH A FATTER HOTTER SPARK ACROSS A WIDER GAP (more energy discharge) to better ignite the fuel

If you only replace the coil and run a wider gap and depending on the coils specs you can indeed force it to fire at a higher voltage but at the expense of possible premature point burn up if youre exceeding the normal current.......

I agree with my buddys, use hotter plugs,,,,,,get n keep the temp up to 180 and over,,,,,,dont run the carb over rich,,,,,,,give her 2 aspirins n call us Monday at the office

John T

 

[tejope]

Thanks. I feel a lot smarter now.