mpriestley

My Feedback: (1)

Hi Bill,

I have just finished running my engines againg for a c-130. I broke another exhaust valve spring on one engine! this is a brand new, OS part. The engine seemed to run great, I only went to 10k (9800-10k) rpms and it was running rich. At the time the engine died, the engine rpms were in the 7k range, approximately 1/2 throttle.

I used some 20/20 fuel from Power Master, this is brand new fuel and different from the fuel I ran the first time I had all 4 exhaust springs break on the engines. At this point the other 3 engines are running fine and have not broken the brand new replacement valve springs.

Can you give me any guidance here? Truly frustrated and confused, this time I know I did not over heat the engines or over rev them.

Biggest concern is whether I will feel confident flying a plane that is prone to engine failure.

the only adjustments to the engines has been the main needle valve, everything else is stock

Please help.

Thank you,

Mike

Bax

My Feedback: (11)

We've not seen any particular difficulties with valve springs for any of the O.S. four-stroke engines, so we'd not know why an exhaust valve spring would keep breaking. The intake and exhaust valve springs are identical. The ony thing that may be causing it is either bad valve lash or running at a too-high RPM. 20/20 fuel may be a bit high regarding oil and nitro content. We'll usually run Omega 10%, sometimes 15%.