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Engine basics => Engine set up tips => Topic started by: fernando torres on October 25, 2010, 09:56:12 AM

Title: OS Max 40la r/c
Post by: fernando torres on October 25, 2010, 09:56:12 AM
I just bought  the used os max. In order to convert it to controline one needs to remove the carburator and add a venturi and a nipple(since the nva is in the back of the motor). I wonder if I can just leave the carburator and fix it wide open, and adjust the needle accordingly?
Title: Re: OS Max 40la r/c
Post by: David Shad on October 25, 2010, 10:13:40 AM
Sure...It works well...many C/L flyers use it just like that...wired open then adjust the needle for your run.
Title: Re: OS Max 40la r/c
Post by: Paul Wood on October 25, 2010, 03:58:35 PM
That's exactly what I do.  I fly the plane with the carb open and the needle leaned comfortably for good fuel mileage.  Then I begin lowering the prop pitch until I get close to the lap speeds I want.  It's usually still a little fast, so I reduce the carb opening until I get the RPM down to a comfortable lap time.  Now I've got good lap times and excellent fuel mileage.  I bolt a wire from a motor mount bolt to the carb arm and just adjust the carb arm to get the RPM I want.  Works very well for me.  I'm flying a TT 42GP, OS 45FSR and OS 46LA.  Works great on all these engines.

Paul
Title: Re: OS Max 40la r/c
Post by: Geoff Goodworth on October 26, 2010, 04:13:10 AM
Or Fernando, you can use standard OS parts to convert it. Take the rear NVA off and use the FP25 Venturi, Tower No.LXCW99, and the front NVA, Tower No. LXCR49.

It's a straight drop in.
Title: Re: OS Max 40la r/c
Post by: Douglas Ames on October 27, 2010, 07:51:30 PM
Or Fernando, you can use standard OS parts to convert it. Take the rear NVA off and use the FP25 Venturi, Tower No.LXCW99, and the front NVA, Tower No. LXCR49.

It's a straight drop in.

...And if it's an early .40LA with the integral RNVA you can replace the backplate with aluminum one from a .40FP. (+ a gasket)