fuel adjust needle and seat Zenith 2

P

Peyton

Senior Member
I have a well used Zenith 2 carb which did not seem to cut off gas flow to the cap jet when the fuel adjusting needle was fully seated in the seat.

I tried drilling the seat area slightly to smooth the edges of the seat area but this did not seem to help. In fact, it probably worsened the situation.

Then, I drilled and tapped the seat area and placed a brass seat in it. The needle seems to seat well but now the gas flow seems to completely cut off when the adjusting needle is closed 1/2 to 3/4 from full seat.

Does this make sense?

Thanks!

Peyton
 
Update:

Worried that the top of the brass adjusting needle seat might have covered the passage leading to the cap jet/ secondary well, I removed it and cut it down enough to allow for the free passage of gas to the cap jet/ secondary well.

I reinstalled the seat and it appears to cut off the flow of gas to the cap jet when the GAV is fully closed.

I drove the car just enough for warm up but the GAV still requires 3/4 turn open to run smoothly. I only drove about 3 miles.

Peyton
 
Sounds to me like it is working, you may still have part of the path restricted, but if it runs good at 3/4 of a turn open, I say that is ok.
 
There are 2 sources of fuel supply to the cap jet. One is through the compensator jet and secondary well and the other is through the gas adjusting knob. If you turn the gas adjusting knob off some fuel should still flow to the cap jet through the other path.
The fact that you can control the mixture with the gas adjusting valve is a good thing. As long as the carb doesn't have any other issues I would just run it.
 
Over the years many different hands have been on that carb. Not all adj.needles are the same. You could have the right one,or one off a tillison or marvel carb. The end is different ,some are longer/shorter Same goes for the gav.
Wick
 
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