The Stovebolt Site Forums The Shop Area Engine Shop Carter YF 2100s rebuild

I've never been completely sure, but I've always thought it was to help smooth or buffer fuel pump pulses...maybe to help stabilize the needle a bit more (particularly on engines which don't flow as much fuel through as others). It appears on many Carter YF carburetors (if not most of them). Currently I'm going through a Carter YF 4145s and it also has that extended standpipe...about 2mm shorter than the one used in your carburetor. That carburetor also has some other interesting differences. More to follow. Unfortunately I have not been able to find much data on it...fuel inlet orifice size being one question. I may have to guess at that.

I asked several questions right in a row. Anyone got an answer on this one? (See original post for pic)

Yes...in some of the YF models the metering rod arm sat parallel to the pump arm piece. This would have been the early models. And your 2100s could have been an early model or a late model. In 3 3211s carburetors I've learned 2 were early and one was late. In the late models the metering rod sat at an angle and was only supposed to touch at the rear (or far depending on your point of view) edge. How to know? How was it sitting when you first started? Parallel? Then I'd guess it is a reasonable thought it is an early model and you shouldn't worry about that. Not parallel? Maybe it is a later model. I wouldn't lose any sleep, though. If your pump rod and your metering rod are hitting bottom at the same time (and on the pump it may be that the small clip is what is bottoming out), you should be right where you need to be.

I didn’t take note before I took apart.

So you’d advise making the adjustments internally vs messing with the external linkage thingee?

Not exactly sure I'm following...there is an adjustment of the linkage for the pump. Is this the question?

I interpret the instructions as:

Metering rod arm should just barely touch the pump lifter link when the pump shaft is bottomed out. Mine touches well before the pump bottoms out.

To correct this condition, do I adjust at the external pump linkage? Or internally at the little arm where one would adjust the metering arm?

I was interpreting your post as “don’t worrry about adjusting at the external linkage.” But I have have misunderstood.

I can't read your attached instructions well enough, but here is how I would put this: First, the flat part of your metering rod arm should sit parallel to the flat section of the pump lifter link. In an ideal situation, they'll be just barely touching and parallel. To adjust this, at the bottom of the float bowl, there is a link rod which can be bent to adjust the travel of the pump lifter link. I'm assuming you don't have one which was designed so that only the rear edge of the metering rod arm touches the lifter link only at the rear edge.

Once this is ok, you need to adjust the metering rod. To do so, press down on the top of the pump shaft until it won't travel any further. Often there is a small clip on the pump diaphragm rod which stops movement but some models lack this. If your rod has the slot cut in it and the lower diaphragm bonnet, it needs that little clip. When the pump shaft won't go down any further, your metering rod should hit the casting (meaning it should bottom out) at the same time. You can usually see when it bottoms out if it does so before the diaphragm rod bottoms out or press on top gently if you think it hasn't bottomed out yet when the diaphragm rod bottoms out. If you need to adjust that, carefully bend the lip on the metering rod arm.

To me it sounds like your pump lifter link needs to be raised or your metering rod is bottoming out much too early. Either one might cause what you described.

The pictures posted are too small for me to understand, but I posted factory Carter service procedures on my website years ago.

Here is the one for the YF:

https://www.thecarburetorshop.com/Service_Carter_YF.pdf


YF CARBURETOR

Back out throttle lever set screw to allow the throttle valve to seat in the bore of the carburetor. Press down hard on upper end of the diaphragm shaft. Press hard enough to compress the upper spring -until you can feel the diaphragm bottom in the casting. With throttle valve seated and diaphragm shaft held in this position the metering rod should be bottomed in the casting. A side to side movement of the carburetor should allow the upper end of the metering rod to slide freely back and forth over the metering rod pin.

Adjust by bending metering rod pin lip on the metering rod arm up or down.

The use of tool T109-212 will greatly facilitate making this adjustment"

Jon.

I think this site went down while I was posting.

This setting is critical. I don't bend anything until I'm absolutely positive that I am doing the test correctly.

Here is an old posting that I found but I would follow Carbking's advice.

https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=76806

Let's look at some images and hopefully that will make it easier. This is a YF4145s which is different but is becoming my good and interesting friend. In a few weeks, I have an idea it will become some member's new good friend also, but more on that later.

First image shows the link you'll bend to adjust the pump lifter. Yours may look different, but this is what I have in front of me now and fairly common. Bending this will cause the lifter to move up...or down. It won't change the angle of anything.

Second image shows how the metering rod arm and the lifter sit when nothing is happening. Pretty well parallel, but not spot-on exact.

Third image shows me pushing the metering rod down to give you an idea of how much movement exists here. Please pay no attention to the spring-loaded gizmo there. That is an idle vent mechanism which isn't in earlier models.

Fourth image shows me holding the diaphragm rod down as far as it will go. At this point the two are both parallel and just touching (meaning I might slide a sheet of paper in there if I wanted to) and if you check the metering rod, it will also just be touching the bottom of its travel. And that's ideal for everything.
IMPORTANT NOTE: always adjust AFTER the throttle body to float bowl gasket has been installed and the throttle body and float bowl have the 2 screws installed.

Fifth image shows where the metering rod arm can carefully be bent to adjust the metering rod if needed. I use a pair of needle-nosed pliers and work very carefully.

Hope this helps.

If you happen to have one of the newer ones, here word for word are Carter's instructions from their form 16C-13-861 (A.C.C.1986):

Fig. 3 Accelerator Pump Adjustment
(GM and Checker Only) and Metering Rod Adjustment
(AMC/Jeep up to 1972; All others up to 1969)
1. Hold throttle valve closed. Press down on top of accelerator pump shaft until it bottoms
2. Metering rod arm should now contact pump lift link at outer end near spring
3. To adjust, bend accelerator pump connector link at lowest angle (and by this they mean the link shown in image 1 below).

And in this same Carter publication,

D. Metering Rod
AMC-Jeep up to 1972
All others up to 1969
1. Hold throttle valve closed. Press down on top of accelerator pump shaft until it bottoms
2. Metering rod should seat at same time metering rod contact pump lift link between springs and at support lug.
Note: On early models that do not have a support lug on lift link, metering rod arm should contact and be parallel with pump lift link when metering rod is seated.
3. If metering rod is not seated or seats before arm contacts lift link, adjust by bending arm up or down.

Thanks, all!

I think you’ve all more or less confirmed my understanding. But my time to work on this is sporadic, I’m usually not in front of the carb when I’m asking these questions, and my use of terminology is probably not correct or confusing.

**** I do believe, based on the Carter instructions provided by Carbking Jon, and the pics provided by Jon G....that I need to adjust the external pump linkage. I think “widening” (making more obtuse) is the way it needs to go. In my simple brain, without the carb in front of me...that’s what needs to happen.

Widening can easily be done with a plain screwdriver and narrowing can be done with needle-nosed or similar type pliers. Sounds like you're on the right track.

After quite a bit of back and forth and back again last night....

I think I have both the external pump adjustment, and the metering rod adjustment, about as good as I can reasonably hope to get. I found this to be quite a fussy task.

Thanks to all for the help. I didn’t have time to do the float settings and do reassembly, but should be closing in on completion. I did perform a function check on the accelerator pump with some minerals spirits in the bowl. That all seems good.

Carb is all assembled. Revisiting an earlier question with a picture. The hole to which my finger points in the throttle body....will be blocked by this gasket.

Do I need to modify the base gasket for that hole to see manifold vacuum? I blew air in it, and can’t determine where it goes.

Anybody have experience with that sort of gasket on a 2100s carb?

Thank you, Jon.

That info led me to search the Carter part number, which led me to an older thread where you linked this picture.

Gasket pics

Long story short, my gasket looks like that one.

Any chance you have a picture showing the side of the carburetor where the throttle and choke linkage is attached. I'm curious what the correct throttle linkage bracket looks like.

This bracket? The choke and hand throttle cables, with associated hardware, connect almost the same same way as the original Rochester B.

Thank you buoymaker thats what I was looking for.

Snapped these yesterday but failed to get them posted.