Walbro carb fuel inlet

[Chris Lane]

I have reconfigured my Zenoah 38 SC with a carburettor inlet elbow. This has brought the black plastic fuel pipe nipple, on the Walbro carburettor, pointing in an awkward direction. I have tried (gently) to turn it but it resists. Is it actually possible to alter it? Advice please. . . . .

Chris Lane

[Peter Smedley]

I doubt it but there are plenty of Walbro service videos on YouTube.

[Barrie King]

Hi Peter
The black plastic is moulded on to a sedated brass nipple that is a push fit in to the carb body it will turn and come out but not easily. I found this out when a friend crashed his model and it broke off the plastic bit. Hope this helps.

[Chris Lane]

Thanks for your replies guys. I had a look at getting the carb apart, to see if I could push the inlet out from the back, but it is in the body and removing the nearest cover does not access the back. It looks like a complete dismantle to do that. I also looked at turning the carb over 180 degrees on the elbow but there seems to be a vent channel which only lines up one way!

I will order a new inlet and then drill and slot a piece of bar to fit over the pipe so that I can line it all up and apply torque carefully. If it breaks it then it is a matter of extracting the brass core and pushing in the new part at the angle I need.

Chris Lane

[Phil Clark]

The fuel nipple can be rotated................but it is a very delicate job and done completely at your own risk. (the following description came to me from Toni Clark)

The moulded plastic nipple will jump a spline or 2 on the brass insert. If you insert the plain shank of (IIRC) a 2mm drill bit into the nipple (to stop it crushing), gently grip the main body of the nipple in a pair of pliers & rotate using the drill bit as a 'handle' for a little added force. It's stiff but it will go having done it several times myself.

Phil

[Chris Lane]

Thanks for that advice Phil.

As this was clearly going to be risky I drilled a piece of 10mm Al bar 7mm dia. and then milled a slot down from the end with a 3/16" end mill. This fitted nicely over the fuel inlet nipple. I lightly clamped the carb body in a vice in the vertical slide on the Myford and lined all up with the 10mm bar in the chuck. This allowed me to guarantee that I was applying pure torque to the fuel nipple. A 2mm drill wouldn't fit but a Number 50 drill did. I had to apply quite a load on the chuck (by hand!) and eventually there was a snap sound and the nipple moved and could be rotated. The slot in the bar was subsequently found to have been spread slightly!

Got there in the end but frightening. . . . .

Chris Lane

[Peter Smedley]

I would have been really worried by the sound it made. Is the fuel nipple still tight in the carb body??

[Chris Lane]

It remained stiff to turn after the initial sound and it still seems to be tight. I have yet to try petrol through it. If it proves faulty I propose to extract it and tap the hole for a proper banjo fitting.

Chris Lane