Linkert parts

Cotten!

Yep, I have waaaaaayyy to much time on my hands! I was bored and thought it would be interesting to video the nozzle. Like you said, it's not road conditions but kinda interesting nonetheless.

As to the subject of this thread, I was tryin' to eyeball where my throttle plate is set in relation to the idle and transition holes and it appears it's just past, at my setting, the transition hole at idle. I thought Panic wrote that the plate should reside on the slot between the two holes at idle. When setting the idle I just do like everyone else and set by sound and feel and it seems right....for me anyway. Not sure what this means, if anything, but jus' wonderin'....

Mr. Big!

The plate cannot be "on" the slot, or the disc would be fully shut.
His wording is vague, but he is not here to elaborate.

....Cotten

Well, kinda what I was thinkin'. So, the described setup of air entering the transition hole, mixing in the chamber and exiting the idle hole at idle is fubar? Man, I dig learnin' this stuff......

Mr. Big!

No, it is not "fubar", that is the way the 1943 Armored School Handbook describes it, basically.

Panic's pamphlet (my copy is ancient) summarizes some basics, but seems to only raise more questions.
His description of the nozzle holes' effect is a bit inscrutable.

Pity that he ran himself off, as any different perspective stimulates thought.

For all of my study of Linkerts and the preceding DLX Schebler design, I am still in awe that they work at all, as much of it remains a mystery. (Schebler H models are pure enigmas!)

....Cotten

As long as Linkerts are the topic of discussion, I have a couple of questions. First does anyone use a gasket between the nozzle and venturi on the 40 and up carbs,and what if any effect is noticable raising or lowering the nozzle. Second, the ID of the nozzle is considerably smaller for the Indian Linkerts. Any ideas why this is, and what would be the consequence of using an Indian nozzle in carb for a knuck? Speaking of nozzles and venturi's I recently made a quick and dirty tool for alignment of the nozzle, a 40 and later engine case alignment stud is a close fit to the ID of the bowl stem. I took an old stud, turned one of the threaded ends down to 3/16, the approximate size of the hole in the venturi and added a 15 degree taper to the last 1/8" or so to start the tool in the hole. Even with a very snug venturi, it is easy to line it up perfectly by tapping the stud in. Maybe you fellas with better eyes hit the mark perfectly every time you press in a venturi, but I'm not that lucky and this simple tool makes it a breeze.

I froze my Indian venturi, to get it to fit, and after some work, I got my Indian fuel nozel stabbed. It took a few stabs to get it in the hole, though, which should be normal.

Cotten!

Thanks so much for your insight on this stuff. I find these little carbs amazing in their simplicity and complexity at the same time. Kinda like my ex-wives........but I digress.

The idle circuit does seem quite a conundrum based on what has been written on it's working's and what actually works in the field. Panic even submits that if the throttle disc is past the transition hole at your idle setting, then the "fix" would be to drill a small hole in the throttle disc. My throttle seems fine where it is so I guess if it ain't broke, don't fix it! And, If I remember this correctly, once the disc is past the transition hole, isn't it supposed to become another idle hole and provide more fuel?

"Panic even submits that if the throttle disc is past the transition hole at your idle setting, then the "fix" would be to drill a small hole in the throttle disc. "

This is a trick to cars with holley carbs and big overlap cams. Start out small and work biger with the hole if you go to big you can solder the hole and re-drill but that takes some time.

44

Kyle asked:
"...does anyone use a gasket between the nozzle and venturi on the 40 and up carbs,and what if any effect is noticable raising or lowering the nozzle."

Damn good question.
I use a thin seal with any used venturi, just because there is always some wear.
Kyle's question applies to the differences in height of the shoulder beneath the spigot, which was greatly shortened with the M75 and later nozzles. (Sorry, but my comparative pic is on a thumbdrive at the shop, and I can only access this forum on my wife's confuser, as the forum format is WAY too modern. My other PC's just show a black marble background.)

Although I cut .090" PEEK spacers to make the later nozzle's match the original M5's etc., I haven't the slightest clue as to the TRUE effect of raising or lowering the nozzle and its holes. The effect of the holes themselves is pure conjecture, from my studies, anyway!
A savvy dyno operator, which is far, far, far, more rare than dynos, might be able to give us some valuable insights if he had a relatively stock machine to study.

"Second, the ID of the nozzle is considerably smaller for the Indian Linkerts. Any ideas why this is, and what would be the consequence of using an Indian nozzle in carb for a knuck?"
The Bonne Indian nozzle is in the same realm as H-D's, but Indian's Standard nozzle is restricted.
To make things more complicated, the tiny Indian M741's nozzle is virtually the same as H-D's Flatty nozzle even for the ULH.

We can conjure all kinds of un-proveable theories ( I occasionally lay awake at night fretting over nozzle holes, honestly), but I prefer to remain just a student who just reports his findings, for now.
I profess blind faith in the Founders who concocted these miraculous devices in the first place. I prefer at this time to preserve History as it was, although we all hunger to re-write or improveit.

"I recently made a quick and dirty tool..."
Kyle!
Kyle!
Kyle!
Drop the hammer now, and nobody will get hurt!

Think "cam action".

My tool inserts without damage, and a revolution centers the venturi without stress.
I would post a pic, but it's proprietary. (You can fondle it at D-port if you like, but no caliper please!)

Mr. Big!
Your description of Panic's hole in the disc is a new one to me; I have no experience from the four-wheel'd world at all.
My Victory pamphlet is ancient, and does not mention anything like that.

....Cotten

I can tell you that the lower the nozzle sits the richer the jet needs to be to idle and run right. Right up to the time you need to progressively close your choke to keep the machine running, and then it stops:) I unwisely chose to replace the bottom crush washer and bowl gasket just before going to Daytona, it is around 150 miles one way from home. The bike run good on the way there and acted up on the return trip only making it to within 5o miles of home. Seems the spring is actually there to hold the nozzle up, even on a nozzle with a light press fit, no spring and the nozzle slowly lowered till she run no more.

Here's a pic from the Linkert Book that shows an M74 nozzle and it also shows a gasket. Palmer doesn't mention a gasket but I swear I read somewhere that one was required on some nozzles. I'll keep diggin'.



Panic also goes into some detail about various mods to the nozzle tip and location in the venturi from drilling holes in it to cutting it shorter to cutting slots in it to.....well, a lot of weird stuff. Then he says they're mostly just theories. I'm pretty sure the Linkert engineers placed the nozzle tip in the best possible location in the air stream and modifiying it would most likely result in less than desirable performance.

I'm pretty sure the Linkert engineers placed the nozzle tip in the best possible location in the air stream and modifiying it would most likely result in less than desirable performance.

I'm gonna go with that too, Mr. Big.

As I mentioned previously,
My copy of the Victory Library is quite dated....
It mentions a few alterations, with no real explanations beyond conjecture.
I have pics of many from the "fossil record" myself, but suggesting any effect is just armchair racing.

Even if somebody does implement some of these alterations, the results will remain subjective without hard numbers.
Without some applied science, it is all just boogered hardware.

The only beneficial "trick" that is universally acknowledged is to shave shafts and solder in the discs, thus allowing a few more cfm at full tilt.
An M75 with a shaved chokeshaft and knife-edged disc just crossed my benches this week.

....Cotten

Great to see some thoughtful input here. Hey Tom, no animals were harmed in the making of my tool. It's not like I was wacking away with a two pounder and some old twisted piece of scrap metal. The problem I have with your cam action tools is the pressure they exert towards the interference, making the action you seek more difficult. But I am very interested in how you made a tool that would have clean contact inside a venturi.

Cotten! (and other interested parties)

Well, it's hotter than blue blazes around here but I forced myself into the sweatbox known as my garage to learn something about Linkerts today. My main goal was to install the 1-1/4" Frisco bombsight venturi in my M51 (see other thread) but also to eyeball exactly where my throttle disc sits at my idle setting in relation to the idle and transition holes. And lo and behold, there it sat exactly as described in the Armored Handbook and by Panic. Fubar? It appears not.



I am still left wondering how enough air/fuel enters to make it go boom, but there ya go. I can hold it to the light and actually see a bit on the opposite side of the disc from the idle holes. Is it enough? Apparently it is......

Mr. Big!

If the plate fully closed, it should shut down the motor.
If the motor could run with it fully closed, the idle screw would be useless.

The implication is that the angle of the disc is still effective even when a significant distance from the idle bleeds.

I've been in awe of this for years.
Just like the enigma of how the idle bleed slot was machined so immaculately for productions of tens upon tens of thousands, while Twenty-First Century producers haven't come close even with EDM.

Kinda like: How did the ancient Egyptians construct the Pyramids.

....Cotten

Cotten!

Yep, the idle circuit is pretty amazing. After a little 45 minute jaunt on Sunday, I pulled in the garage and turned the idle screw all the way closed and it still wanted to run. Very slowly mind you and would have died had I Ieft it there but an 1/8 of a turn open brought it right back to my original setting. So I guess the correct idle position for the disc resides just at the beginning of the transition hole and what I find amazing are the very small changes required to accomplish that and how the edge of the disc interacts there. Am I in the ballpark here?

Thanks so very much for your input and advice. You are a gentleman and a scholar!

I made a mistake in a reply about Tom's tool for aligning the venturi a while back. He sent a picture of the tool and I had pictured something entirely different. I made a small dent in my head with my hammer as a reminder not to make assumptions. Tom, being the good guy he is just laughed it off, but I wanted to make it clear that my criticism was completely unfounded.

Kyle!

Show anybody else that tool, and I WILL be perturbed!

Let us see if anyone else can figure it out on their own.

...Cotten

So I'm not the only one who misses Panic.

Seems to me that someone
kept the water
and threw away the baby.
.