Re: Leaking crankcase leads to overheat condition?

[johnyrude200]

I just got done running the motor sustained at 5500 RPM in my test tank with test prop for 5 mins on 2 separate trials. This is only bout 3/4 throttle in the tank with the wheel. I found that it was still running a bit hot, not on the temp gun (stayed at 145-150° both cylinders), but by pulling the plugs and examining both those and the pistons. The pistons were somewhat wet on the intake side, but nearly ‘white burnt’ dry on the exhaust side. The plugs were pretty dry too. I put brand new NOS J6C’s in for the 1st of the 2 runs.

The 2nd go around, I put J4C’s in. Motor ran a little cooler after 5 minutes of sustained 5500 RPM. I looked at the ’71 service manual and it called for J4C’s. Pulled the J4’s, and the pistons and plugs had a minute amount of fuel moisture. I am guessing initially that the J6’s are too hot for this motor for sustained WOT or high RPM.

I’m going to conduct the test out on my test boat under load in a few minutes. This is a motor that will probably be run at WOT for long sustained bouts since it will be used in an emergency rescue application.

I tried richening up the low speed end, but doubt that is the culprit since the high speed jet is fixed on this unit.