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carburetor trouble seems like a flat spot when accelerating black smoke out tail pipe seems to have more power when choke is on i turn air screw all the way in and it does nothing readjust 3/4 turn still falls on face does anyone have any suggestions how to fix its a 68 willys jeep

68 Willys (What Model) jeep? Which model carb?

its a m18 engine not sure of the carb but it has a manual choke and single throat

The 68 Willys jeep would have a F134 engine with a Carter YS carb.

What is an M18 engine? What model Jeep?

SORRY SOMEONE TOLD ME IT WAS AN M18 JEEP WHAT DO YOU THINK IS WRONG WITH THE YS CARB

It is foolish of me to try and answer your question without first a positive ID of the type equipment having the problem. There are at least 5 or 6 model carbs that can fit the 5 or 6 models of universal type jeeps.

The military jeeps have an ID plate with model and serial on the dash. The civvy jeeps have this plate on the passenger side of the firewall.

The engines have a casting number on the lower right side and a model specific serial number on the small ledge above the water pump.

The Carter carbs have the basic series ID on the side of the body which will be WO, YF or YS. If they have been undisturbed they will have the specific model number on a triangular shaped tag attached to a carb body screw. These various carbs have many different ways of operating the three primary circuits and only by being sure of the series carb you have can we help troubleshoot a circuit malfunction.

These photos will help with the proper ID of your jeep, engine and carb.


Military dash model/serial plates


Engine serial number location


Engine casting number location. The first 6 digits are the primary number.


A Carter YS marking on the bowl body.


Here you can see the triangular tag on the left carb.


Carter WO carb


Carter YF carb

THE CARBURATER NUMBER IS CARTER C 607 MANUFACTURED FOR MOTOCRAFT AND THE ENGINE BLOCK NUMBER IS 807895

Then you have an F134 and this should be what your carb looks like?



1-Black smoke means the mixture is too rich. Too much fuel and not enough air.

2-Runs better with choke on (closed) means too lean. Too much air and not enough fuel.

We have a bit of contradiction in our symptoms.

I am inclined to believe symptom 1. The improvement in performance with choke closed a bit may just be the result of the change in venturi suction. Start by checking float level adjustment and check for leakage into venturi area of raw fuel. Do this with the air cleaner removed from the top of the carb. .

TY for the info took top of carb adjusted float level and works great now