0540 straight valve spark plug gap

[kaos]

Can anyone tell me if the correct spark plug gap for a 0540 straight valve running ACD C87 plugs is .28 thousands?

 

[Mike Thurman]

Try to tighten the gap to about .020. That should probably be best for you.

 

[kaos]

If anyone else can also verify the correct gap it would be greatly appreciated. I now have three seperate answers from 3 diffrent sources. I've been told .020, .028, and .035 for the gaps.
Help !!!

 

[Tony289]

I would go with what Mike Thurman says based on his experience and expertise.

 

[Ruagatr]

Completely agree that Mike's advice is first on the aircraft advice food chain--period. Maddog

 

[Larry]

.18 to .20 is what we normally run our aircraft plugs at. You need a tight gap for a good spark at idle speed with a magneto.

Larry

 

[Tide Runner]

I tried the .18 gap on my 520 and it did'nt work very well .... at wide open i lost about 150 -200 rpm's and the motor would die down like it was running out of gas I have a fuel pressure regulator and gauge on it mainly for the n.o.s.. so i could see that it was not running out of gas and a new carb... so I went back to my old gap .35 top and bottom at it solved the problem also no problem idle.... this works fine at least for me.

 

[mwood7800]

I also tried the smaller gap and lost rpm on my 540, did not seem to make my idle any different .

 

[Davie GSO480]

If you have the red coil's in your mags', and are running stock compression 20-22 is what I ran in my st8 valve. Mags only put out about 8k volts.
I had an electro mag. on the same engine, made my Charlie Bass, it was an electronic pick-up style mag, using a regular high outout automotive high saturation coil, I set the gap at 35 on that unit.

 

[kb27_99]

Davie,

I run some mags from Charlie as well. I set my gap at .050 with no problems. With my mags i could not set the gap any bigger than .020 before it would idle like crap.


Kevin

 

[mountain man]

koas

I have a charlie bass mag as well
do you know were to get parts for them?

 

[kb27_99]

Moutain Man,


I go through a local place here in Louisiana. But all in all they get the parts from Pro-Tronics. You can call pro-tronics and find out who is a dealer near you or call Summit, they can get pro-tronics parts.

Pro-Tronics part #'s:

Cap - 022-1602
Rotor Kit - 020-1003
Igniter - Module 4 Marine

Pro-Tronics 1-800-827-3758