adjustable main jet

[muddy]

hi all

does anybody have any clue where to start setting up an adjustable main jet? giving my old girl a going over, and im not really sure where to start with it.

ill set the timing back to stock, then get the mixture screw out to standard, but then ive got no clue how to set the jet up in order to get the mixture right. idle speed you can set up after that easy.

i want to have everything running sweet before i stick the twin carbs on, so i know that any issues will be isolated to the new carb setup.

cheers
james

[muddy]

anyone?

[FB MAD]

It's best to set up adjustable main jets on a Dynanometer with exhaust gas analyser as this is the best method of adjusting them to gain the best power output along with the best economy and engine tuning.

I've only fiddled with a few of them years ago at Tech College in my apprenticeship on the tech college dyno and set them up that way.Memory's fading a bit on them as its over 25 years ago since then .

It would be a trial adjustment without a dyno.Screw the adjuster in and unscrew a bit ( do both carbs the same if twin carb setup ) and take for a run and see how it goes.If no good keep adjusting until you are happy with it at all engine rev and load conditions but still best to dyno the car to get them tuned better to the engine you are using.


Maybe try Google Australia and type in "adjusting main jets" or similar key words and see what comes up.

Hope this little bit of info helps.

[muddy]

its a bit hard to come by any info!

i figured, as it doesnt really do much at idle, i gave the engine big revs (as much as it will see in day to day driving) and wound it in till it struggled, and backed it off again.

noooo worries.

[Dr Terry]

These were quite commonplace on taxis in the 60s & early 70s.

The general rule of thumb was to turn the knob clockwise over time until the exhaust valves are burnt to crisp & then back off 1/2 a turn.

Or better still put it in the rubbish bin, where it belongs.

Dr Terry.