need suggestions for vx18, starts and idles fine, main needle out 3 1/4, runs at 280 to 300 F, using 20% nitro fuel, RC9 plug, body has multiple openings for air, just replaced O ring around main jet, not sure what to do next, truck was running on pavement. thanks

ok what is the temp outside when you were runing it, and seal all of the openings, around the backplate, base of the carb, and around the highspeed jet. you may be runing the engine in too hot conditions, and swap the plug out for a McCoy MC-59, They are the best plugs and i have never had one blow.

temp was in the mid 80's in the evening as it was cooling down, my mistake on the plug it is an MC-59, what should I use to seal? thanks

black rtv sylicone....also check your fuel lines and tank for air leaks......are you running it hard on the throttle or is it mostly low spds?...if your running alot of low spd you might be lean on your low spd needle...3 1/2 should be plenty on the high I would think

no... you should use red sencer safe gasket maker. it is safe for up to 400F

Cole.....

If you are hitting 300 degrees with Those needle settings, you Probably have an Air Leak someplace.

Likely Places for air leaks are Exhaust Manifold, base of carburetor, Back Plate of engine, Cracked Fuel Tank or Bad O ring seal on cap of gas tank, and bad fuel lines.

And make sure the 4 screws that secure the engine Cooling Head are tight......

A small leak at any or all of those places will cause Temps to Skyrocket beyond what is safe for your engine.

Here is a link to a Sealant that is made for RC's and is immune to the Nitro based fuel that we use...
http://www.amainhobbies.com/product_...ducts_id/17237

Thanks! I am working on it this week and will keep you posted, I never thought to look at the gas tank, just the lines from the tank. The tank is the only item that has not been touched or replaced. This is the second engine with the same problem. Cole

One way to tell easily if the gas tank is leaking around the cap seal is to look for echaust smoke coming out of the tank cap around the edges. If not then take the two fuel lines off, plug one of them off and blow gently into the other line. You should be able to blow some pressure into the tank with out if bleeding off too bad or at all.

Update - replaced fuel tank, fuel lines, sealed the engine and the engine is now running around 230, this is great! Thanks a ton, I believe it was the tank. Thanks for all the support, it was a good lesson for me. Cole