knormang

My Quadra runs fairly well, but on close examination I have noted the following.1. The inside of the engine is shiny new.2. The piston is approx. 40 mm. diameter. 3.It has one ring. 4. The Walbro carb has 20c stamped on the bottom and c8.The hole for atmospheric pressure is offset from center. My question is this. Is there a different Walbro I could use to give more power?Do the later model 40's have 2 rings?

w8ye

My Feedback: (16)

I cannot remember but I was thinking that the present day ones have a Walbro with a 11mm or 11.13mm venturi. The walbro will have a 27 or 28 cast into the inlet venturi area.

The most popular Walbros for model airplanes with this size carb are the WT-499 and the WA-167-1.

As big as the engine is, it possibly could use a carb with a 1/2" venturi? These have a "32" cast into the inlet.

Whatever carb you use, it must have both high and low speed mixture needles.

Also if it is a carb with a fuel return outlet, this must be plugged or run through a bulb pump or check valve and returned to the tank.

Here is the site for Quadra spare parts...

www.bennettbuilt.com/page1.htm

Source for Walbro carb data

http://www.prestwich.ndirect.co.uk/walbrocarbs.htm

knormang

Thank you W8yE, very helpful.