1920 Harley Model F

[TechNoir]

There are times I wish 'metric' was more available here, John!

We are reasonably fortunate here that whilst we are officially metric, most inch sizes are also readily available, not as easily as metric but certainly not uncommon.

So,... How do you plan to cut the notch to fall perfectly upon the idle screw?

....Cotten

I was thinking I should get the disc right first and then, with it in place carefully mark the notch position and cut it out small piece at a time.

Unless you have a better method?

John

[T. Cotten]

.. Unless you have a better method?...

Not much better, John!

I fixture the disc firmly in the shaft, indexed within the carb body at 'zero daylight', and then rough out the notch through the idle screw hole itself.

Then it still has to be tediously filed/stoned perfect, re-installed for inked inspection a couple of dozen times at least.
(As it was for the friction disc...)

I never could charge enough, but I had no other way to get it right.

....Cotten

[exeric]

Tom is right, the notch is a tedious job. I see things like this in ancient objects and I stand in awe of the engineers, and fixture makers of that day who figured out how to do these things efficiently, productively, and somehow made money doing it.

[T. Cotten]

Tom is right, the notch is a tedious job. I see things like this in ancient objects and I stand in awe of the engineers, and fixture makers of that day who figured out how to do these things efficiently, productively, and somehow made money doing it.

Its the lost lore of the Ancients, Eric!

Even with my forensic study, I would be a bigger fool to guess how they did it. But here goes...

They made lots and lots of batches. Then they could pick through them for the best fitting hardware, but it still took genius (George Schebler himself), resourcefulness, and worker dedication nearly extinct today.

(Even Linkert's idle slot is still as enigmatic to me as the Egyptian pyramids.)

....Cotten

[Steve Swan]

i very much enjoy following the discussions in your thread, John. Particularly Cotten and Eric's comments, not to mention yours, you guys are into some advanced stuff that i can glean some information from at least as much as i understand what you are talking about. When Cotten was talking about the idle slot, it brought me back to when i was under Bob Paulette's tutelage, this would have been in the mid-1980's, i drew out the idle circuitry, you can see that idle slot, thought you might enjoy perhaps.

idle slot.jpg

[T. Cotten]

We are getting off-topic, Steve!

(Although they lacked the L&L slot, Schebler's DLXs originated the dual circuits design, 'idle' and 'power', so we have left the HX zodiac, but still in the galaxy?)

Did Mr. Paulette give any insights as to how the idle circuit suddenly reverses itself?
We know the Armored School Handbook explains it as when the vacuum at the nozzle becomes sufficient, but...

Does it always flush itself like a toilet, or if held at that critical RPM, might it gurgle and reflux?
Any observations are noteworthy, thanks!

....Cotten
PS: Yeah, the "flat spot".

PPS: Were there any earlier designs with "circuits", Anybody?
(Not that it could knock George off his pedestal; I've just never held a Hedstrom or any of the really early ones in my hand.)

[Steve Swan]

We are getting off-topic, Steve!

(Although they lacked the L&L slot, Schebler's DLXs originated the dual circuits design, 'idle' and 'power', so we have left the HX zodiac, but still in the galaxy?)

Did Mr. Paulette give any insights as to how the idle circuit suddenly reverses itself?
We know the Armored School Handbook explains it as when the vacuum at the nozzle becomes sufficient, but...

Does it always flush itself like a toilet, or if held at that critical RPM, might it gurgle and reflux?
Any observations are noteworthy, thanks!

....Cotten
PS: Yeah, the "flat spot".

PPS: Were there any earlier designs with "circuits", Anybody?
(Not that it could knock George off his pedestal; I've just never held a Hedstrom or any of the really early ones in my hand.)

Alas, the answer is no, Tom! What i remember Bob saying is something to the effect the disc need to be adjusted to position between the two holes. I'll look through my notes from those times and see if i can find anything else that might illuminate. Sorry, John, not wanting to hijack your build.

[T. Cotten]

That only confirms my suspicions, Steve,..

That the absolute simplicity of the HX models made them the foundation of all that came later.
(Was there an alternative? ? .. .. . What other inspirations may we have lost?)

Unfortunately, it takes a at least an amateur watchmaker to approximate them now.

I was never that, but I do have some watchmakers' tools!

....Cotten

[TechNoir]

Sorry, John, not wanting to hijack your build.

No need to apologise, I am learning too so please carry on.

John

[T. Cotten]

..What i remember Bob saying is something to the effect the disc need to be adjusted to position between the two holes....

He was correct of course, Steve!

But that is entirely determined by the angle upon the disc.
(Attachment shows it as best I can...)
It cannot be adjusted; The disc is either in its 'sweet spot' to close fully, or it isn't.
A higher angle places the disc forward toward the big hole, and a lower would place it toward the rear.

(This brings up a question about L&L's different angles for different 1½" models. If we assume the throttle shafts were in the same place, does that mean the idle bleeds were shifted fore or aft? Everybody swore how simple Linkerts were... Yeah, right.)

Bringing this back to HX models, the angle determines the shape of the idle notch on the disc.
Note how the top of the notch is not quite square to the axis of the shaft. The lower the degree of the angle, the closer it comes to square.
The top of the notch also has an angled face, that should close upon the barrel of the idle screw. A square cut would never close completely, but probably run anyway.

....Cotten

[T. Cotten]

This pic, Folks,...

Shows much better how the idle notch is not easy.

(Please note that the friction disc must be perfect first.)

....Cotten

[Steve Swan]

This pic, Folks,...

Shows much better how the idle notch is not easy.

(Please note that the friction disc must be perfect first.)

....Cotten

Wow. position, shape, angle of notch is critical. i can appreciate at least one of the challenges confronting restoring this carb to like-new function. Tom, you have to know what you are doing and have all the necessary tools and equipment to restore these carbs without test running them before returning them to your customers. gorgeous soldering job. following this conversation, i am somewhat more able to appreciate why the H model Schebler can be challenging to work on.

[T. Cotten]

Uh... Steve,...

There's always just one more tool necessary.

And the disc in the pic has not yet been soldered; It came back out for filing and inspection dozens of times.

Nobody in their right mind should attempt to do it "right". Lest you lose your 'right mind' as I did.

....Cotten

[TechNoir]

; It came back out for filing and inspection dozens of times.

Nobody in their right mind should attempt to do it "right". Lest you lose your 'right mind' as I did.

Thanks for the pictures Cotton. Patience is certainly a commodity that is required to work on these old carbs.

The saws that I ordered have not arrived yet. The supplier I used usually deliver in about 24 hours but this COVID crisis is slowing everything down so it looks like I will have to wait until after the Easter weekend to test my own patience.

John

[T. Cotten]

Thanks for the pictures Cotton. ..

Here's a couple more, Folks!

I'm probably stupid to be altruistic (it always bit me in the ass..), but I'm probably soon out of business anyway.

...Cotten