What type of emi beads should I use to help suppress ignition EMI . Should I use type 43( 40 -200mhz) , type 73(10-50 mhz) or type 77 ( 2 -30 mhz) ? What kind of freq are being put out by the ignition unit and the spark itself ? Thanks

This may be the wrong section (gas engines) for a question like this. You might get more response in the radio section.

I don't know of anyone using emi suppression ferrite beads. I have 6 gasoline engine powered airplanes and they are all flying on PPM (commonly known as FM) radios. I do not have the slightest hint of radio interference. This comes about by using well established techniques for preventing radio interference and good equipment. No chokes, noise traps, or opto isolators are used.

Sorry that I didn't answer your question. Maybe someone else can.

Ken

Seems like RFI covers the entire frequency spectrum..The very first spark gap radio transmitters were like that, they covered everything...

its not at all critical, I use rings and make three turns