Darren Bos wrote:
David, I was looking at the valve in your parts list and it looks like a plain valve with the knob and needle valve oriented 90 degrees to the flow path, while the knob on the Maxie is aligned axially with the needle of the valve. Were you thinking of a different arrangement to control the fuel flow? Or maybe you would locate the valve in what is now the drip tube of the Maxie?
I threw in this valve as an example of a low-cost easily obtained needle valve, which avoided the skilled task of making one, but I must admit that I don't have a clear idea of how to use it.
I found, when I couldn't turn my needle valve and had to use the shutoff valve at the tank, that the burner was very slow to respond - not surprising with nearly a metre of hose. What this teaches me is that the needle valve must be very close to the burner, and that it must have vapour flowing through it, not liquid fuel, to respond quickly. It must be downstream of the area where vaporisation takes place (which, I think, is just behind the burner chamber on the Maxie), and just upstream of the final exit hole, with not too long a path between the two, and not too voluminous a tube downstream of the valve. This creates a difficulty with any separate valve, and it may be that the built-in valve is the only way to go. I don't know. Perhaps what's needed, so long as a separate valve can withstand heat well enough to be close to the burner, is to have the flow horizontal through the valve, with the spindle (extended) pointing outwards towards the operator.