To really eliminate the foaming fuel problem, you need to have someone holding each wingtip of the model while the engine is running and while you are visually examining the fuel line. Most times, the fuel foaming won't manifest itself with the landing gear sitting on the ground. This is what is so tricky about diagnosing fuel foaming.

I agree, with a 1/4" of uncompressed foam around the tank and without the brass tubing touching any part of the firewall solidly, you shouldn't have fuel foaming, but that doesn't mean that it won't happen. If you're running larger than a 12 oz. tank, consider dropping back to a 12 oz. tank to increase the amount of isolating foam. Most pattern flights can be completed with an unpiped engine with just 12 oz of fuel. If you find yourself running short and are running nitro higher than 5%, drop back to 5%. The 100 to 200 rpm you'll lose off the top end won't be missed, but the extra minute or so of run time can make all of the difference.

Learn how to balance spinners, if you are not balancing spinners now. That too can add a few hundred rpm to the top end and will naturally reduce fuel foaming tendencies.

Don't mind me if you already know this stuff. <G>


Ed Cregger