whats this part in my carby??

[Zaczac]

anyone know what this part is in the bottom of my carby.
As far as I know its a stock FB standard.
I just put a kit in carby and my manual and the kit dont explain this part.
It screws in and out with a needle tip like the air/fuel mix screw but it is in bottom of fuel bowl??

thanks
jas

[fingers]

anyone know what this part is in the bottom of my carby.
As far as I know its a stock FB standard.
I just put a kit in carby and my manual and the kit dont explain this part.
It screws in and out with a needle tip like the air/fuel mix screw but it is in bottom of fuel bowl??

thanks
jas

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
thats a non standard fittment mate ....its an adjustable main metering jet ..... ..Fingers

[Zaczac]

so what does it do and how do I adjust it?

[fingers]

so what does it do and how do I adjust it?

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
What it does is varies the size of your main jet to gain maximum fuel encomy ..........the further you screw it in the smaller your main jet becomes ....but remember if you run too lean you can burn out valves and run high temperatures ....... .....so be wary
If you havent already adjusted it just leave it and get an exhaust gas analyser test done ...........if you have undone it .........screw it up till the needle touches the main jet then back it off 1 and 1/2 turns so it will start then get the engine up to around 2500 rpm adjust slowly each way till it runs best ....then get someone with an exhaust gas analyser to do the final adjustment .......just rough but should get ya going .....and check with Harvs carby guide in the engine section of this
forum .... ...Fingers

[Zaczac]

Ah thanks ill give that a try. I just started her up after doing the kit and runs really nicely but i noticed a very slow drip out that mixture screw when out 1-2 turns. Is there a 'goo' that could be used in the thread? That still allows adjustment?

[fingers]

Ah thanks ill give that a try. I just started her up after doing the kit and runs really nicely but i noticed a very slow drip out that mixture screw when out 1-2 turns. Is there a 'goo' that could be used in the thread? That still allows adjustment?

...............................................................................................................................................................................................

From memory the part that screws into the carby should be reasonably tight and it seals with a brass or aluminium washer ............then the shaft seals by tightening the gland nut which should seal that ....if it doest work , dont drive it with a leak mate ..its would be very dangerous ..I would consider getting a standard 50 or 51 jet to replace the adjustable one ...maybe Harv will have a suitable solution if that doesnt work ......HHHHHHHHHHaaaaaaaaaaaaaaarrrrrrrrrrrrrvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv.............................................Fingers

[Zaczac]

thanks all good its not even rego'd yet.

I will have a look at it tomorrow as there did not appear to be any washer etc but I may find one in the kit if im lucky.

it comes out 1 turn before leaking out the shaft part

[Zaczac]

Doh I'm such a dumbass sometimes

The screw is fine, i simply was not screwing it in enough. I didn't want to force it so stopped when it started to feel tight, then backed it off 1-2 turns, however i should have kept going as it screwed in a lot more then came to a complete hard stop.
So its all good now!

[Harv]

G'day Jas,

Fingers is right - looks like an adjustable main metering jet. Take a squiz at the Guide here:
http://www.fbekholden.com/forum/viewtop ... 25&t=14756
... down the bottom of page 64. You have a big lump of brass (that sits outside the carb) with a needle tip, then inside the carb you have special jet with a seat to match the needle tip. If you pull that jet out (you will need a jet key), the next thing up the hole is the main discharge jet, which comes out using an Ezi-out. Sounds like you left the main discharge jet in during overhaul - not a show stopper, as long as everything was flooshed out well with kero/thinners and blown out with compressed air.

Screw the big lump of brass of the adjustable main jet out and you get more fuel under cruise conditions. Screw it in and you get leaner. It then gets really tempting to screw it in more (wow! really good fuel economy!!!). The mixture gets leaner... and leaner... then you fry the valves. If you are lucky, you get warning signs like running hot, surging at 60mph cruise, or white looking sparkplug electrodes. In the old days, you could tune them by looking at spark plug colour. In a lead-free era, plugs are a lot harder to read, and exhaust gas analysis is really the best bet if you want to keep the adjustable main.

I'm not a big fan of adjustable mains - a standard jet is a lot safer (especially if you run the odd tank of E10 through the old girl). The O-ring in the big lump of brass also tend to leak over time. You can get standard jets from the Carburettor Service Company (see the contacts at the end of the Guide).

Cheers,
Harv

[Zaczac]

thanks for all that info.
I got it sorted and wound it open about 2- 21/2 turns to be on safer side as its not a driver yet and before it gets on road it will be at my mechanic anyway to RWC and tune her properly.

Just doing brakes etc first.