HI i have an older webra silverline 61 can you tell me the best size apc prop to run on this engine- and the RPMS i might expectusing an 11/6 apc running a little rich at 12,30012,4000 would like to run an 11/5 apc or should i be thinking -11/7 thanks

I think 11x6 is as small as I'd go. 11x7 or 11x8 are probably best for that engine. Those are the props the engine was designed to turn.

David

HEY DAVID thank you for your inputTONY

My 1960's webra 61 (10cc) runs best with a Master Airscrew 12 x 8 Prop, it likes heavy props:- I found wood ones
to have Idle issue and problems with midrange.


Johnkpap

I was gona suggest a 12~6 as most of these older .60s were designed to use. The rpm may be down a bit but depending on the plane this could make a good combo. Mainly, you have to do a bit of experimenting.

Terry in LP

If this is a 70's or 80's Silverline, i expect the 11-7 prop would be best. Especially on a pattern or pattern like aircraft.