Linkert M74B

[T. Cotten]

This is fully closed and fully opened

when the disc is closed is it normal to have the gap with the idle screw all the way backed ouf?

When the disc is fully opened the lever is on the carb body stop

With the idle screw backed out, Jack,

The disc should close completely against the bore wall at the idle bleeds. With the bleed plug removed, the disc should be visible in the middle of the idle slot:

DISKBLED.jpg
(Model shown is other than M74B, but the position is the same.)

The idle screw, when turned in to slightly open the disc for initial starting, becomes the 'closing' stop.

I must note that to inspect for daylight around the disc, the choke must open; I inspected with even the venturi removed for certainty.

....Cotten

[Iacovos]

With the idle screw backed out, Jack,

The disc should close completely against the bore wall at the idle bleeds. With the bleed plug removed, the disc should be visible in the middle of the idle slot:

DISKBLED.jpg
(Model shown is other than M74B, but the position is the same.)

The idle screw, when turned in to slightly open the disc for initial starting, becomes the 'closing' stop.

I must note that to inspect for daylight around the disc, the choke must open; I inspected with even the venturi removed for certainty.

....Cotten

Well noted! Thanks for your reply Cotten!

[Iacovos]

The “damn” thing fired up on the first go!! This 64 did not run for 10 years now!

Big Thanks for all the input for the linkert rebuild! Much appreciated everyone!

No gas leaks (was worried as was my first carb rebuild …..)

Oil pressure switch not working (had to check oil circulation hemce the seat being up)

[Iacovos]

QUESTION FOR KNOWLEDGE:
Upon rebuilding an M74B if the venturi is stuck in the carb bore and one does not remove it (or fix it being stuck) will it cause any problems with the running / starting etc ?
What are the consequences?
Why go to the point of pressing it out (by force). Also i read about a "light gap".
I have never got my head around this and could not find an answer in the forum
THANKS

[T. Cotten]

QUESTION FOR KNOWLEDGE:
Upon rebuilding an M74B if the venturi is stuck in the carb bore and one does not remove it (or fix it being stuck) will it cause any problems with the running / starting etc ?
What are the consequences?
Why go to the point of pressing it out (by force). Also i read about a "light gap".
I have never got my head around this and could not find an answer in the forum
THANKS

Did the main nozzle come out easily, Jack?

Fuel residues can combine with moisture to 'cement things together, but disassembly is manditory for cleaning the 'air correction' chamber (extreme example shown).

SNDYVNT.jpg

It is common that once the 'crust' is removed, original venturies will be quite loose, and show daylight around them;

DAYLIT88.jpg

CLNYVENT.jpg

Most break loose with penetrant and a heat lamp, but I've had plenty, especially Scheblers, that sounded like a firecracker in the sixty-ton press.


....Cotten

[duffeycycles]

I use a paint stripper heat gun until it is pretty hot to the touch. Never need the big pressure just patience but Cotton has done waaay more than me.

[BigLakeBob]

Original Paint 1958 Harley Davidson Duoglide Overview and preservation

15 min to 18 min might help

[T. Cotten]

I use a paint stripper heat gun until it is pretty hot to the touch. Never need the big pressure just patience but Cotton has done waaay more than me.

I got all the sick puppies, Duffey.

Heat guns risked warping out potmetal Scheblers, and igniting solvents, so I played it safe with heatlamps:

CHEMSOAK.jpg

The important part was cutting accurate drifts.

I tried to scroll to view the video, BLB, but as soon as I saw him pick up an eight-inch farmer screwdriver, my blood pressure flared, and I had to click off for my own good.

....Cotten

[Iacovos]

Thank you everyone for sharing all these helpful hints based on experience!

T. Cotten let’s assume main nozzle came out easily. What does the air correction do in the venturi operation and why it needs to be there? Does it affect priming/starting? Or the running of the carb?
can it create imbalances with the LS or HS circuits?

Thank you for the feedback in advance

[T. Cotten]

The "air correction circuit", Jack,

Supplies air to the main nozzle, critical for speeds over ~35mph, and rapid acceleration.
In this case, Air enters a hole through the side of the casting to the venturies' annular void (shown full of crud in my previous post), where it can then purge the nozzle's cutaway upon demand,






The Armored School Handbook best explains the function:

accltxt2.jpg

The idle circuit is even more inscrutable.

.....Cotten

[Iacovos]

Thank you Cotten,

Now it starts to make sense! Will make some more reading of course, just for the knowledge of this.

THANKS