RCU Forums - Spray bar location

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Spray bar location

This is the noob forum so I don't feel too bad asking this question: where is the spray bar in a four stroke (.91 ASP)? Is it basically where the high-speed needle enters the carb inlet?

With that question out of the way, here's why I am asking: I am installing the above engine in a Big Stik 60, and I have two ways of installing the engine. If I install the engine upright, then the spray bar (assuming the location is as I described it above) would be about 1.5" above the tank center line. If I turn the engine 90 degrees, then the spray bar would be between 1/2"-3/4" above the center line so that's probably the better set up. I just want to ensure I am measuring the location of the spray bar correctly.

Thanks.

RE: Spray bar location

Hi ppkk,

The spray bar is the tube that the high speed needle screws into.

Hope this helps with your set up.

Cheers,

Colin

RE: Spray bar location

Quote:

ORIGINAL: ppkk

This is the noob forum so I don't feel too bad asking this question: where is the spray bar in a four stroke (.91 ASP)? Is it basically where the high-speed needle enters the carb inlet?

With that question out of the way, here's why I am asking: I am installing the above engine in a Big Stik 60, and I have two ways of installing the engine. If I install the engine upright, then the spray bar (assuming the location is as I described it above) would be about 1.5'' above the tank center line. If I turn the engine 90 degrees, then the spray bar would be between 1/2''-3/4'' above the center line so that's probably the better set up. I just want to ensure I am measuring the location of the spray bar correctly.

Thanks.

On the ASPs I've seen, the center of the carb's rotating throttle drum is your reference point. That's actually true of all engines, even when they have a remote needle valve. Where the fuel is introduced into the intake air is the reference point.

Your idea about bhe better setup is spot on, mate.

RE: Spray bar location

Alright, a follow-up question: what would happen if I mount the engine upright, which would put the spray bar location 1.5" above the tank center line? Would this cause the engine to run lean?

The reason I ask is, this plane is designed for the mount to be installed upright. If I turn the mount sideways, then the location of the nose gear rod would no longer line up and some modification would be needed. Nothing that is not do-able, but I'd rather avoid it if it the location of the engine doesn't cause problems in the future.

RE: Spray bar location

Hi ppkk,

Give it a try. Many motors will tolerate a small variation in height. If you don't achieve a reliable motor run it may well be easier to add a pump or regulator rather than re-configure the mount and nose leg steering set up.

Merry Christmas,

Colin