What range glow plug do I need to use for 55% nitro? Thanks

I run OD Blues with 50% nitro. That is considered a cold plug. In theory, more nitro needs a colder plug, but different engines may like different plugs....

My local hobby shop doesn't do boats.I don't imagine they know what a OD Blue is. So,in number ranges,about what would that plug be? Thanks

For High Nitro(over 40%) Generally you want a Cold Pug glow plugs are categorized by Heat Rang not by number. Ask your LHS for a Medium Plug and a Cold Plug and see which works best for you. I prefer McCoy Plugs over the OD plugs, a McCoy MC9 works very well for Me running 60%nitro 12%oil.

Thanks

MC9's a good choice. Very sturdy plug but don't expect a good low idle out of it which you shouldn't be concerned with anyways, but with my experience it needs the glow driver left on till theres a little bit of heat in the motor, or it likes to stumble at idle and quit.

Will be using 55% nitro-17% oil in a 18 an 15 motor.Thanks again.

I don't really have any Idle issues on the smaller engines,, After the engine Warms Up and I get the Air\Fuel mix dialed in,, That may be partially due to the fact I run a lot lower Oil% than Most and mix my own fuel so there are Minimal Additives to inhibit corrosion. The only Non essential additives or Dyes in my fuel are what comes in the Klotz Oil's.