Cotten ! - linkert differences

[1950Panhead]

Linkert used .187" and .240" low speed holes.
On the large hole the lever follows the choke cam when the choke is closed.
On the small hole the lever only follows the choke cam part way.
Same cams, is this normal ?

[T. Cotten]

1950Panhead!

Curiously, 1" Model Ms had a .248" 'idle well hole', ±.001"

Generally, 1½" models were .186"-.187", and 1¼" models were ~.240". However, I currently have a couple of M-35s on the bench either way, proving once again there is an exception to every rule.
(Why were Indian 1¼" models the smaller bore? And another mystery is why for late M74B productions did they "choke" the well down to ~.120" for the bottom inch or so?
It only adds to the mystery that the bores were always produced just shy of a nominal drill size.)

As best I can eyeball from what I have on the bench, all three sizes of Model Ms' lift levers "follow the choke cam" in the same arc, even the 1" model with a different lift lever.

What am I missing?

....Cotten
PS: The various spring collars over the well were air metering orifices.
They must slide with the action of the lever, however so slight. Their hole should be inspected for oval wear, and the LS needle should be observed for wear against it.
The variety of collars is worth study, as they have mysteries of their own.

PPS: After guessing that your carb on the left might be an M-75, I pulled one of them off the wall, and sure enough, it is another 1½" model exception with a large idle well bore.
But everybody swears Linkerts are "simple", right?

[1950Panhead]

Cotten !
The larger hole allows the needle to tilt more which allows the lever to follow the cam.
The smaller hole restricts needle tilting so lever does not follow cam.
I have M16, M18, M35, M51,M75 with .240" hole
I have M35,M61,M74,M74 with .187" hole.
Photo lever on cam with choke open.

[1950Panhead]

Left carb - lever does not follow cam (.187" hole)
Right carb - lever follows cam (.240" hole)

[T. Cotten]

1950Panhead!

T'ain't the hole. Too many tens o' thousands of them work...

Something else is binding it.
(Honestly, I never even attempt an assembly until it has all been cleaned and thoroughly prepped; It saves tail-chasing. That ain't a Tiaranian lift lever, shown on the right in the attachment, is it?)
If the needle is hitting the side of the hole, that's not good either.

Make certain the hole in the casting for the shouldered bolt isn't skewed up. (I remember a poorly-installed helicoil doing something like that.)

....Cotten
PS: I have (at least) three 1"ers on the bench with a fatter well hole.
And they are liable to sit here until somebody reproduces an accurate lift lever! (Like on the far right in the second attachment, but I could use Scheblers like on the left as well..)

PPS: Since your hardware doesn't look prepped, please make certain the knob spring is on top of the needle and not beneath it. That would certainly reduce its angle of 'play'.
(Any stone unturned hides something to bite you.)

PPPS: You can guess now why I can't staff my shop!

[1950Panhead]

Cotten !

Thanks for responding to my post.
Some pondering then eureka, spring on top (others are confused).
I posted on caimag yesterday but no wise men came forward.
I was laying in bed last night with visions of linkert parts dancing through my head when I remembered you and caimag parted ways.

Jerry

[T. Cotten]

Don't feel bad, 1950Panhead!

I have received Tiaranian lowspeed needle assemblies fresh in the bag with the spring beneath the needle.
(Wrong spring too.)

....Cotten
PS: You will find little evidence that I ever had anything to do with caimag. Wish there was zero.

[ryan]

I am not knowledgeable about Linkert carbs at all, but I sure would like to be. I kind of always liked tig welding copper and bronze metals.

I use to have to weld beryllium copper quite a bit. I remember getting beryllium copper poisoning from wire EDMing the nasty stuff. At first I thought I just had the flu. My mouth tasted like a penny for a week after I finally felt better.

You guys, who work with these worn out carbs, must have some really neat tooling and fixturing.

[ryan]

Talk about being slow to the trigger, now I see and finally understand what you all were talking about on what was missing and different about my M53 carb because it does not have these parts.

So if I am understanding this correctly, applying the choke not only shuts down the air, but it also enriches the fuel as well.

My reply was not intended to hijack nor sway the conversation, I just had a light bulb moment.

[T. Cotten]

Ryan!

The choke mechanism design of 1¼" DLX Scheblers was incorporated upon almost all production Linkerts, with the exception of yours (and before I get ragged at.. the "barrel" racing series).
The choke control tab with a detente in several positions actuates a shaft with a choke disc, and a cam to move the lift lever.

When the disc is closed, the lift lever lifts the LS needle high from its seat allowing a larger volume of both air and fuel to the idle gallery as it is pulled into the choked carb bore by the motor when kicked. Please note that there is a spring collar beneath the spring that lifts the lever, and the hole through which the needle passes is an orifice to meter air into the idle well.

Linkerts are so simple yeah right.

...Cotten
PS: My TIGmeisters usually made a mess for me to clean up. So I rely on much more friendly silver solder.

[ryan]

Thank you Cotton for the lesson on how the carb chokes work.

I could not dream of welding inside the bore or barrel of a carb. be
There is always a low area around the weld no matter how you not to get one. Now building up a broken ear would be a different story. The guy "Tatro" I was watching soldering up the barrels ended up boring and opening up the barrels way to large, I would think, leaving about .005" clearance between the barrel and the venturi. How would the carb work well after that? I am pretty sure over sized venturis are not available or you would not be soldering the barrels up.

Anyway, too many questions with not enough time.
Thanks again Cotton, greatly appreciated!

[Rubone]

Ryan, just cut a new oversize venturi. Not difficult to do.

[T. Cotten]

Ryan!

I routinely swage potmetal venturies oversize, and lathe-cut them to a light press fit for oversized bores.
(Ironically, after months, they shrink again to a slip fit, but they stay round. A 'bombsight" probably couldn't be swaged.)

This is far more economical than scratch cutting, as it only takes twenty minutes compared to over an hour, no aluminum billet, and saves the original that otherwise would be useless.

They can be brittle from "zinc pest" however, and no two are the same, so its more art than science.
When one cannot be saved, its still cheaper to swage a Colony venturi than scratch-cut.

If your borewear is minimal, just a fresh Colony may suffice.

....Cotten

[cdndewey]

I'm familiar with swaging boiler tubes in a tube sheet of a fire tube boiler and tubes in a shell and tube heat exchanger...but how does one swage a venturi in a carb body? That's a new one on me.

[T. Cotten]

I'm familiar with swaging boiler tubes in a tube sheet of a fire tube boiler and tubes in a shell and tube heat exchanger...but how does one swage a venturi in a carb body? That's a new one on me.

Carefully, Dewey, carefully!

As I described, it is not swaged in the body, but outside, and then lathe-cut to fit.
I have carved a selection of fitted cones for a screw press. Models and vintages vary in technique. There are critical tricks of course, and pitfalls to watch out for, but I must keep my cards close to my chest.
Everybody should enjoy as many failures as I have.

.....Cotten
PS: A little common sense goes a long ways: If it looks like the one in the attachment, don't ruin the "History".