Carter YS rebuild question

DaveP · Post by **DaveP** » Fri Jul 08, 2011 4:10 pm

Hi Everyone,
I'm rebuilding the Carter YS carb from my M38A1 and ran into a missing part from my carb. It's titled ball (item em T on the diagram) and weight (item U). I have the weight but there was no ball when I took the carb apart for the rebuild. Any idea where I could find one as the rebuild kit didn't include it?

Also I managed to break off the brass screws the hold the throttle plate to the shaft. It looks like a #3 screw. Should I drill these out, tap, and replace the screws?

Thanks in advance,
Dave

DaveP · Post by **DaveP** » Fri Jul 08, 2011 4:18 pm

The ball is listed as HH on the diagram on the downloads section of the website. That is the one I am missing.

Post by **wesk** » Sat Jul 09, 2011 8:40 pm

Hello Dave,

Which carb kit do you have? The kit from MWM & AJB as well as the Kit from Ron F's G503 parts both have that ball and the screws in them.

Both are very common to several hundred Carter Carbs so try using the Carter part numbers at your dealer.

ball 116-13

Screws 39-11

If needed I can get the dimension from a ball and you can purchase the plain steel balls at most hardware stores.

DaveP · Post by **DaveP** » Sun Jul 10, 2011 8:28 am

Hi Wes,
The carb kit that I have was purchased from willysjeepparts.com. Maybe I should call them and ask if they have the ball and screws available that weren't included in the kit? I'm a little new as to the best sources to order parts from for these Jeeps so I just went with one of the first ones that came up.

Thanks for the part numbers. If the place that sold me the carb kit can't get them I'll try searching with those numbers to see what comes up.

Thanks,
Dave

Post by **wesk** » Sun Jul 10, 2011 9:43 am

Are you using the Carter OH manual download TM 9-1826A exerpts from our downloads page? The manual can be used for the YS950S but the illustration and specs for the 950S are not in there due to the manual's published date of 1952. It's best to use the carb blow-up from the M38A1 ORD 9 for your rebuild.

http://www.willysmjeeps.com/downloads/YScarb.pdf

The parts blow-up is the incorrect version with the metering rod diaphragm spring on the wrong side of the diaphragm. Also the M38A1's YS950S data is not in there.

This is the corrected parts blow-up

The spring on the left is the correct accelerator pump spring for the M38A1.

The M38A1/M170 YS950S specs are:

Carter YS Carbureter No.950S http://www.m38a1.ca/carb.html

CARBURETER SPECIFICATIONS

For Willys 4 Cylinder Engine: 3 1/8 Inch Bore, 4 3/8 Inch
Stroke

Dimensions: Flange size, 1 1/4 inch S. A. E.
Primary venturi, 11/32 inch I. D.
Secondary venturi, 19/32 inch I. D.
Main venturi, 1 1/4 inch I. D.

Float Setting: Distance from seam of float to float chamber cover, with weight of float on needle and spring: ¼” (9/64 inch was in the original Carter pub).

Vents: Balanced thru air horn to air cleaner via tubing external to carbureter.
Vent: Bowl chamber to carbureter bore, size No. 68 (.031 inch) drill.

Gasoline Intake: Square vertical (spring loaded) needle No. 53 (.0595 inch) drill size in needle seat. Bleeder tube, assembled over idle tube, with 2 side holes--No. 65 (.035 inch) drill.

Low Speed Jet Tube: Jet size, No. 70 (.028 inch) drill (in end of tube). Auxiliary jet (on side of tube) size: No. 75 (.021 inch) drill. By-pass (in air horn) size: No. 52 (.0635 inch) drill. Economizer (in body) size: No. 54 (.055 inch) drill.

Idle Port: Upper port: slot type, length, .165 inch. Width, .030 inch.

Idle Port Opening: Top of port--.125 to .129 inch above top edge of valve with valve tightly closed.

Lower Port (For Idle Adjustment Screw): Size, .053 to .057 inch diameter.

Set Idle Adjustment Screw: 1/2 to 1 1/2 turns open. For richer mixture, turn screw out. Idle engine at 700 R.P.M. with deep fording vents open.

Main Nozzle: In primary venturi, angle 20°. Discharge jet size, .0935 inch inside diameter. Main nozzle bleed (tube in air horn) Size: No. 70 drill.

Metering Rod (Diaphragm operated): Economy step, .070 inch.
Power Step .054 inch diameter.
Vacuum passage restriction, size: No. 50 (.070 inch) drill
Vacuum passage bleed to bore, size: No. 65 (.035 inch) drill.

Metering Rod Jet: Size: .096 inch diameter.

Accelerating Pump: Diaphragm type, vacuum operated. Discharge jet size, No. 72 drill. Intake ball check size: No. 40 drill. Discharge ball check under needle, size No. 50 drill.
Vacuum passage restriction, in flange size: No. 52 (.0635 inch) drill. Vacuum passage air bleed to bore, size: No. 62 (.038 inch) drill.

Pump Stroke: No adjustment.

Choke: Manual--Offset, butterfly type with poppet valve.

Vacuum Spark Port: None.

Specifications come from a one page bulletin from Carter Carburetor Form
4960B released March 1953, revised March 1956. I have tried to keep the
layout of the form. However, it should be in two columns.

Back to F-Head

Sean MacLennan
Last modified: Wed Mar 06 21:49:16 EST 2002

DaveP · Post by **DaveP** » Mon Jul 11, 2011 10:16 am

Thanks for the diagram Wes. I'll make sure to reassemble it correctly once I get those missing parts.

DaveP · Post by **DaveP** » Mon Jul 18, 2011 10:15 am

Hi Wes,
If possible, could you take a measurement of that ball for me? I'm having no luck getting a reply from the place that I bought the rebuild kit from and can't seem to find any Carter parts dealers online that would have it.
Thanks,
Dave

Post by **wesk** » Tue Jul 19, 2011 11:31 am

The used balls were 0.1537 dia

The new ball in Ron F's kit was 0.1535 dia

The new ball in the AJP/MWM kit was 0.1540 dia

All three sizes work just fine.