Post on default pilot screw settings

[StuartWags]

I saw a post, i am sure, quoting default mixture screw settings for 50 and i think bigger pilots.

Anyone know what i am on about or was it too many beers?

[VTRDark]

default mixture screw settings for 50 and i think bigger pilots.

Too many beers as that's the same thing. You mean 50 pilot jets.

I'm not sure default is quite the right word, maybe baseline to get you started, but this does depend on other settings like needle height and mains too. You will find around 1.5 turns out with everything else as standard/ish will get you started.

45 approx 3.5 turns out
48 --- 2.5 -- --
50 --- 1.5 -- --

See the pattern there. Larger (richer) pilot = less turns out (leener) on the fuel (mixture) screw. Think of the fuel mixture screw as your fine adjustment for the pilot jet.

Apart from the pilot circuit being the main idle circuit, don't forget that the pilot circuit also has an effect throughout the rest as it tapers off towards the mains. It has more of an effect on the bottom end of the needle circuit than it does the mains top end. There will only be a trickle and barely noticeable top end. So be aware that if you go richer on the pilot circuit then you may need to leen off the needle circuit a tad. Of course this has a bit of a chain reaction, lean of the needles and then you may find that the mains need richening up a tad.

That's the basics of it.

Ideally what you want is an even balance across all 3 fuel circuits including the transitional stages as they cross paths, all falling at the correct Stoichiometric ratio according to revs. Generally starting on the lean side lower revs/speed for max performance benefits, harder on the engine with more heat, and as revs/speed increases richen up a little with slightly less performance but max engine longevity and better cooling. On a side note: not so much an issue with standard compression but less chance of pre-ignition from too much cylinder heat. So for example you might start off at 14.1 and end with 12.1. But this requires dyno time. One can only do so much by feel, so do the best you can and then verify with a dyno run and adjust accordingly.


(:-})

[StuartWags]

cheers

[AMCQ46]

Cheers for that Carl, I was just trying to work out if it was a fuel screw or an air screw and I had decided fuel... You just confirmed it for me.

Mine were at 1.8 turns but I can't remember if I swapped the pilots when I put the jet kit in 10 yrs ago