M53 non bombshell carb

[ryan]

It is still going to be hard to give up the M53 because it does not seem to have any wear whatsoever.
I had a conversation with an older gentleman that needs a 1954 top end and he happens to have a knucklehead top end he may want to trade. Mine runs, his parts are off the motor. I really do not want original heads because of all the work involved in getting them reworked. Not sure what to do really. I am uneducated on any engine below a 1966.

[T. Cotten]

Don't be afraid to use the M53, Ryan!

The difference in choke mechanisms would only be noticed in very cold weather.

The lift lever was probably just a hold-over from the Byzantine-but-immortal Scheblers anyway.

....Cotten

[ryan]

I was reading about the M53 Linkert and found a difference in bore sizes between the M53 and the M53-A1, so I measured mine to be 1.500" and looked at my number again and my carb is indeed M53-A1. Just an update.
Thanks

[Rubone]

Ryan,
Is it stamped M53A1?? The body bore size is the same on an M53 and An M53A1. They are both 1-1/2 bore carbs.

[ryan]

Yes, It is stamped M53A1. I missed it the first time because I did not see the A1 on the other flat. I had read somewhere, and I will give the link, that the M53 had an 1.250" bore.

[Rubone]

Nope, M53 was 1-1/2. Just the venturi configuration was different. All 1-1/4 inch carbs only have 3 mounting bolts. I have a couple of each here, including a NOS M53A1 that will eventually go on my 55KHK.

[T. Cotten]

Its confusing, Ryan,..

...Because nothing on your carb measures 1.500".
The body bore is 1.5625", and the venturi bore is 1.3125"
The "nominal" term for 1½" Model M Linkerts is a hold-over from Schebler's nominal terms of 1" and 1¼" models, which were not 1" or 1¼" either. The three nominal models are easiest to distinquish by their different manifold flange patterns.
The 1" models have three ¼"-24tpi bolt holes in a triangular pattern on a small flange with no spigot (with the exception of Indian Fours with the bottom holes threadless). The 1¼" models have three 5/16"-18tpi bolt holes on a larger flange, with a spigot.
The 1½" models are like yours with four holes in a trapezoidal pattern on an even larger flange, with no spigot.

....Cotten

[ryan]

OK, back to my M53-A1 carb, As I mentioned before, the bore or barrel looks to be in great shape, but I have not torn it down to measure it with a bore gauge. I know the carb needs work because the throttle butterfly hits the venturi, the float is brass and the main nozzle falls right out. Anyway, I need some help with this thing.
Thanks

[T. Cotten]

Ryan!

Its been many years, but I believe although the M-53 retained the venturi with a 'nubbed' screw through the side of the body, the -A-1 had a simple screw to plug the hole, and the venturi was retained by the nozzle spigot in the ordinary fashion. If the throttledisc is hitting the venturi, it has moved to the rear a bit. It must come all of the way out anyway.

And athough the bore may have minor distortions from over-torquing the flange, etc., the principle area of concern would be an 'eyebrow' groove caused by the disc rattling against it.
Most folks toss them together and hope for the best, but excessive daylight around the disc, or a groove that approaches the idle bleeds means that the carb will not tune in "as good as new". The usual complaint is a difficult transition between the idle an highspeed circuits.

Did you find a #9 fixed jet?
Was the point of the lowspeed needle 'stepped', like on the left in the attachment? (M74, no "B", on right for comparison.)
And I believe your nozzle should look like the one on the left (both sides shown, common M74b or right for comparison). Please note the wear at the base of the spigot from rattling on the venturi. A gap at this point defeats the "accelerator" effect of the nozzle's void filled with fuel to be expelled upon demand.

....Cotten

[ryan]

Ryan!

Its been many years, but I believe although the M-53 retained the venturi with a 'nubbed' screw through the side of the body, the -A-1 had a simple screw to plug the hole, and the venturi was retained by the nozzle spigot in the ordinary fashion. If the throttledisc is hitting the venturi, it has moved to the rear a bit. It must come all of the way out anyway.

And athough the bore may have minor distortions from over-torquing the flange, etc., the principle area of concern would be an 'eyebrow' groove caused by the disc rattling against it.
Most folks toss them together and hope for the best, but excessive daylight around the disc, or a groove that approaches the idle bleeds means that the carb will not tune in "as good as new". The usual complaint is a difficult transition between the idle an highspeed circuits.

Did you find a #9 fixed jet?
Was the point of the lowspeed needle 'stepped', like on the left in the attachment? (M74, no "B", on right for comparison.)
And I believe your nozzle should look like the one on the left (both sides shown, common M74b or right for comparison). Please note the wear at the base of the spigot from rattling on the venturi. A gap at this point defeats the "accelerator" effect of the nozzle's void filled with fuel to be expelled upon demand.

....Cotten

Cotten,
I will have to get back with you in a day or so on your questions. I am away from the carb at this time.
So, what I do know from memory; there is no eyebrow groove, I think the main jet, pictured, looks to be the one in the middle and also looks to be held in place by 2 screws 90° apart, the rest will have to be looked at, at a later date. Oh, both butterfly plates look to be brand new. Also, from prior readings, I need to buy a float from you.

Thanks again for your help Cotten, I do not expect you to answer any free questions when this is how you make your living. I am very upset, that certain people messed up things for me, that I cannot send the carb to you for fixing. I know a dowry is when money is transfered from a bride or a groom during a marriage, but I do not know if you are up to something like this when related to a carb. Just meaning that if I send enough money to you with my carb if you would even be interested in looking it over. I just do not know what to do with it at this time.

[T. Cotten]

Let me first dispell the any such 'certain people' issue, Ryan!

I am not accepting new work only because I am already booked solid with the very best of 'certain people'.
It is entirely my fault for my limited productivity, but I can still offer my opinions if nothing else..

The term 'jet' gets used universally, so for clarity, the Factory called the drilled-orifice gallery plug on the bowlstem to be a "fixed jet".
The 'spray bar' or 'emulsion tube' up the center of the bowlstem was called the 'main nozzle', and its a mystery to me as to why they apparently used the same nozzle at two different heights in the body. The different floats settings from all the rest upsets me too.
These do not cross my benches, so my info and insights into these is next to nil. I look forward to any clues other forum members can contribute!

....Cotten
PS: What does the idle bleed plug on the right side of the body look like (as you face the carburetor at the intake...)

[ryan]

Ryan!

Its been many years, but I believe although the M-53 retained the venturi with a 'nubbed' screw through the side of the body, the -A-1 had a simple screw to plug the hole, and the venturi was retained by the nozzle spigot in the ordinary fashion. If the throttledisc is hitting the venturi, it has moved to the rear a bit. It must come all of the way out anyway.

And athough the bore may have minor distortions from over-torquing the flange, etc., the principle area of concern would be an 'eyebrow' groove caused by the disc rattling against it.
Most folks toss them together and hope for the best, but excessive daylight around the disc, or a groove that approaches the idle bleeds means that the carb will not tune in "as good as new". The usual complaint is a difficult transition between the idle an highspeed circuits.

Did you find a #9 fixed jet?
Was the point of the lowspeed needle 'stepped', like on the left in the attachment? (M74, no "B", on right for comparison.)
And I believe your nozzle should look like the one on the left (both sides shown, common M74b or right for comparison). Please note the wear at the base of the spigot from rattling on the venturi. A gap at this point defeats the "accelerator" effect of the nozzle's void filled with fuel to be expelled upon demand.

....Cotten

I am sorry for this mistake, but I am almost sure the main jet I have is the one on far right. Again, I will have more info soon.

Thanks!

[Rubone]

Ryan,
I have a factory NOS M53A-1 that has never seen fuel. If you have any questions on it I can provide you with photos.

[ryan]

Robbie,
Thank you for wanting to aid me in a time of need. I will surely be in touch when the time comes. I need to be able to show pictures as well. I am just using a Kindle and not a computer. I need to get a new laptop. Thanks again to Cotten and you!