I just got a pair of FP .35s, and had to come up with a venturi / needle assy on a Sunday before I flew out of town Monday morning. My buddy had an LA .40 so I borrowed the venturi / needle from that. It fit perfectly, but I was wondering if the venturi ID is the same on an LA .40 compared to a stock . 35 FP-S venturi.

I'll be flying the engine in an ARF Oriental in Albuquerque NM. Any suggestions on a good prop? I have stuff scattered across the counrty, so my on hand prop selection in ABQ is limited, and I would rather not buy a bunch of sizes I already have to try and find a good combo. Better to spend the $$ on a couple sizes with a good chance of working.

Thanks

I just got a pair of FP .35s, and had to come up with a venturi / needle assy on a Sunday before I flew out of town Monday morning.  . . .
 . . .
 . . . my on hand prop selection in ABQ is limited, and I would rather not buy a bunch of sizes . . .

Yeah, you got those from Crist Rigotti, right? That means the boost ports are blocked already, good news for you. Smaller venturis (.263 to .265) work better on these, my opinion (assuming stock OS NVA, not fat ST NVAs); steadier run with seemingly no power loss. On 5% nitro, I'm running APC 11.5 X 4, launch at 8800 to 8900, just below the break. The needle setting seems a little touchier on the boost port blocked FP35s with props smaller than that, my experience.

Fuel seems critical. Yesterday (60+ degrees outside temp) I ran two tanks of  a 50-50 blend from two jugs – one 20% straight castor, one 22% oil but half castor. Couldn't keep it from leaning out for last third of tank. So, that is about 21% total oil, and over 15% castor.
   I borrowed a bulb of straight castor 29% from a buddy, and the next flight the 35 FP ran like a pickle seeder. I've been prejudiced towards straight castor in the FP 35s. Yesterday was the first day I've deviated from that policy for over a year – and the first time I've had a problem – in over a year. Summertime, 10% nitro and straight castor has never been a problem either.

   Larry Fulwider

Edit: The standard LA 40 venturi is .275, although I have read of other sizes from factory stock LA 40s