Linkert + elevation

[Aphelion]

Hey Guys,
Just got back from a ride out in West Texas on the panhead. Ive only been riding with the M74b for a couple months and im loving it, but when I pulled it out of my truck in TX and started it, it really ran like crap. Super rich. I was at 4000ft and I live at 850ft. I tried to tune for the elevation but was always on the rich side. I finally did get it to stop smoking, but I was messing with it constantly in the elevation changes. Is that normal? Do Linkerts just perform like shit with elevation change or what???

I have an 18 main jet in there now but im thinking of going even smaller....

Thanks!

[Cotten]

Aphelion!

If you have the later '58 to '69 Service Manual,
it notes that the HS needle (for M74Bs) is a "trimmer valve" to be opened for very highspeed needs, or closed for altitude problems.

The M74B HS needle is ordinarily so insensitive, due to the overwhelming fixed jet, that I usually put them at 3/4 of a turn, and leave them there until there is a need.

Did you ever try the needle closed?
Did you switch from a #19 to the #18?
Where are your needles set now?

....Cotten
(And as a matter of practice,
I must urge you to test your manifold again.)

[Aphelion]

I never messed with the high speed needle. I left it completely closed. If I opened it a little, it got even worse...

I even have it fully closed down here at 850ft.

[Cotten]

Aphelion!

So your lowspeed needle is in a respectable range, no more than about 2.5 turns out?

There have been some despicable fixed jets sold on the market lately, so it may be prudent to make certain that your #18 is indeed .0795" and the #19 is a full .082".

With both needles in their range, and an accurate fixed jet, we must suspect that some fuel is getting to the nozzle well somehow.

So I must ask: the gallery plug next to the Fixed jet is not a common set-screw, is it?
(Proper "grub screws" actually bind to seal upon the threads like an NPT pipe thread. The fixed jet should bind upon its tapered circumference.)

And it is not uncommon to find factory solder repairs upon Linkert body castings. Are any visible upon the bowlstem?

And you are running a buoyant float at book spec, right?

Sorry, but I gotta ask...

....Cotten

[Aphelion]

Thanks for the help Cotten. I am running one of your floats set to 1/4". I re-checked that while I was out in TX riding. You are right about the jet I believe. It is an ebay special and I was weary of the quality before I ever installed it.

The plug on the bowl stem is just a little brass plug that came with the carb.

Can you tell me where to get quality jets?

[Cotten]

Aphelion!

There has been so much new garbage for carb parts lately that I'm afraid to shop.

In the meantime I am drilling out the undersized batch I have in stock.

....Cotten