Stromberg BXV Carby jet adustment

My 56 dodge has a Stromberg Carby BXV with vacuum control.

It has an adjustable Main metering jet, with thumbscrew for fine adjustment (see photo - at base of the fuel bowl).

Can anyone tell me what is the starting point for this jet e.g. is it screw it in still it stops( i.e. jet hole closed) and then back one and a half turns?

these adjustable main jets were an after market thing // you removed the fixed pre set jets and fitted this one /in the stromberg you had the idle jet -intermediate jet -and main jet - you also have the acelerator pump for more fuel to remove the flat spot when powering on -the best way would be with a gas analiser - the main jet would only work properly at high speed so an adjustment at mid range revs would be a good start and a bit of trial and error -if it lags on hills or under load wind it out to give more fuel - in for less --always remember a lean engine will idle slightly higher or even increase revs A LEAN ENGINE WILL BURN VALVES sorry for yelling bt verry important -- a ritch engine will foul plugs run sooty and leave carbon build up in ports and around valves even glogging muflers so the mixture setting is verry important cheers don

set the accelerator pump stroke on the middle hole -underneath //onthe end of the butterfly shaft to the pump plunger // the float level set at 5/8 inch from top of housing cheers don

G'day Geekay, I have fitted many of these over the years and you are right with the starting point. I then bring the revs up around 2000 and holding it there adjust the jet in and out until it reaches max revs then open the jet another 1/8 turn. It can then be fine tuned on the road.

Thanks everyone.
I did set at one and one half turns out and now that I have the timing issue sorted (the clamp that holds the distributor in place on the block had cupped and was allowing the dissy to turn) it is running reasonably.
With your extra information I will be able to tune it better.