Spark plug cost? None of them fit the glow plug hole? No problem.

You can buy these 1/4-32 spark plugs all day long for $17.00 each. They have been around for over 60 years! Made right here is the US of A. On 30% fuel using 1/2 to 2/3 the fuel a standard glow plug engine would use you could buy a new plug every 2 gallons of fuel due to just the fuel savings, crazy argument. I have not needed another spark plug, still on the original, just checked the gap after 120 flights and no measurable change. You will go through a couple glow plugs to every spark plug, but I have not used up a spark plug yet so I do not know the true life limit yet. The quality of idle and transition on a glow plug engine is dependant on the element being in good shape and not covered in, what I call "frost".

I have a C&H ignition, the problem is getting the magnet into to the hub using a nose ring. Being internal as YS did it makes this a non issue and consealed.

Bill