The Stovebolt Site Forums The Shop Area Engine Shop Erratic Engine Idle

What's goes here?

According to the Carter diagram, there should be a check ball in this orifice.

My carburetor had this brass vent tube thing threaded in there with no check ball at all.

How should I proceed? Is this brass stem vent thing a replacement for the check ball? Am I looking at the diagram properly?

Notice that the Carter diagram shows the check ball in the accelerator pump cover in the wrong location. It's actually on the opposite side of the piston than is depicted in the drawing as you can see in the photo of the carb.

As long as I'm asking a bunch of questions, what's the best method for removing the copper plug(s) on the side of the carburetor? And what's the best method for installation?

I know this pot metal is soft and often brittle. I don't want to mess anything up.

What is the large plug for and why didn't Carter just use threaded fittings instead of press in plugs?

The drawing is generic, Carter made hundreds of different YF carburetors.

The threaded tube is the idle jet. It should be reinstalled from whence it came.

The pressed plugs should NOT be arbitrarily removed. These are access plugs. If compressed air can be blown through the passageway covered by the plug, no need to remove the plug.

The pump check valve is off to the side from the idle jet.

Threaded plugs would have added significantly to the original cost of the carburetor.

Jon.

Thanks Jon. I didn't want to remove that big one but since there was a replacement in the kit I thought it might be SOP to remove it during a rebuild.

Does my Accelerator pump assembly look right? In the diagram there's no gap between the connector link and the metering rod arm. Everything looks like it's stacked up right but I just want to be sure.

I know I probably sound like the annoying kid who keeps pestering people with questions.

Otto, I always take pictures, with my digital camera (macro setting), as I disassemble a carburetor.
It helps to refer to them during reassembly and it also helps to spot and record mistakes and modifications made by a previous rebuilder.
The accelerator pump assembly looks good to me. I don't have a diagram of a YF 684S but my YF 2100S has a tiny "pump stem retaining clip"
that fits into a notch on the pump stem. A real pain to install at times. I cannot see one in your pictures because the pump spring is hiding it.
It's possible that your model did not have one.

When you installed the new pump diaphragm did you put a little alcohol in the fuel bowl and operate the pump?
On the up stroke it should spit out a stream at the check ball and retaining clip (bottom of your picture #3).
When you finish the check, dump the alcohol and work the pump to get rid of the excess.

Yes, I took/take a ton of photos along the way. My concern here is that since there are several differences between the carb, diagram, and certain parts, I don't know exactly what is correct since this is the only YF I've ever opened.

The float has had its arms improperly bent in the past so I think I'll have to crack open the Willys carb and use that float. This one doesn't look like I'll be able to achieve both correct measurements.

I did not do the alcohol thing but parts are loosely fitted right now so I can take it apart and do that. The alcohol won't hurt the rubber?

There is a bit of confusion here, the carburetor is not a YF 684s. 684s was a W-1.

Jon.

Now I'm even more confused. What carburetor do I have?

It's a YF somethin' somethin', right?

Bouy, I just did the alcohol test and it seems to work fine.

What is the STAMPED number, ending with an "S" on the side of the bowl?

Jon

If your zip code ends in 032 and you bought it from me it is a 964s.

Jon

Hi Jon

Bowl: 0-824

Venturi: Carter YF

Flange: A77 964S

I used a 9/32 drill bit as a gauge for the first float adjustment. The float in this carb had been monkeyed with in the past and and getting the second adjustment was nearly impossible. Someone had bent the arms instead of the little stop tabs and tongue.

I pulled the float out of the Willys carb and set the first adjustment with the drill bit. The second adjustment was already dead on.

Hi Jon, yes, that's me. I saw that I wrote the wrong number in a previous post. This one is indeed a 964S.

YF 964S...now it makes sense.

I shamelessly stole the attached pictures from a Jeep forum.
Carter went out of business in the mid-80's and carburetor kit providers now sell other needles and seats (fuel valves).
Notice the big difference in the length and how it affects the float.
Gently bend the float tab back to a normal position.
Try not to stress other parts of the float while bending.

Jon H., being a wise man, purchased many original Carter parts before they were snapped up.
Your are experiencing one of the hiccups in rebuilding your own carburetor.
That's why I said you are in good hands with Jon H's kits.

Otto Skorzeny Reach out to our carb king he'll know the low-down on off-shore carbs.

Yes Fixite7, this carburetor and the rebuild kit came from him.

We talked about the Chinese junk clones being pedaled these days.

fixite7,

Jon H
Jon Hardgrove
Carbking

I know I'm probably over-thinking a lot of this stuff but what the heck? In for a penny, in for a pound.

The metering rod has a Carter logo on it with the part number 75-952. The part number in the manual is 75-837.

Does that matter at all? Probably a replacement part installed by a prior rebuilder. It looks the same as the one in the manual.

You might want to call Jon on that question. The metering rod you have will work, however...I have a note that says the metering rod marked 75-952 was used in the 2101S (YF for the 235 with auto choke). That note also tells me the 75-837 was used in the YF965S (YF for the 216, 1937-1952 Chevy and 1953 Chevy truck 216). The 965S was like yours but with auto choke.

The note I have says the measurement for the 75-837 rod should have been: economy step--.074" diameter, middle step tapers to .058" diameter and power step is .047" diameter.

The 75-952 rod on the other hand is .068 economy step, .060 midrange and .050 power step. The main jet in the 2101S was .0945" and in the 965S the main metering jet was .098".

So with a main jet of .098 and using the 75-952 metering rod it looks like you'll be running richer in town than you should (due to the smaller diameter of the economy step) and leaner at midrange speeds and in power mode (due to larger diameter of midrange and power steps on the 235 rod).

As I said, I'd ask Jon H. There is a notable difference in the size of the main jet here and also there's a notable difference between .074" and .068". My guess is some rebuilder swapped parts here. Good luck!

Hi JonG,

Thanks a lot. That's helpful information.

As it turns out, the cobbled up Jeep carburetor that started all of this had an 837 metering rod so I swapped it out.

I'll post some pictures of the finished carb later on.

On an unrelated note, I keep forgetting to send you an email about the condensers. I'll do so today. Suffice to say that the car I thought would be a problem wasn't and the car I thought would be just fine - and for which I got them in the first place turned out to be the problem.

.

Otto. Two words, "swap" and "metering rod" is hard enough for an expert to do correctly.

Jon H. or Jon G., I don't have the four page Carter specification sheets for a YF 964S.
If it is allowed, would someone please scan the pages and send Otto (if he doesn't already have one) and myself a copy?
My gut feeling is that Otto needs to stop work and maybe verify that he has installed the correct parts.

Too late! Thar she blows!

The carburetor and rebuild kit are both 964S so the metering rod is now correct for that carburetor.

Seems to be running fine.

Okay, cool!

The idle seems a little fast but you can adjust that.

Yes, I plan setting it tomorrow. I had it a bit high to keep it running until it warmed up. It hasn't been run for a month or so and hasn't run properly for a couple months before that.

I set the mixture screw halfway between the specs at 1 turn out to start with.

Nice job!

Jon

Thanks Jon. And thanks for all your help with the carburetor and the parts.

Thanks to everybody else who helped with advice and information.

Final Adjustment today on the mixture screw and idle screw. No fuel leaks , no vacuum leaks.

Took it for a spin around the neighborhood and Walmart parking lot. The guys in the auto center are used to me tooling around in various old cars in front of their garage. I go over there to test drive repairs before hitting the highway.

Anyhoo, here it is.

Did someone cut the draft tube?

I think the tube broke off or something before my friend got it. There's a dented up one in a box that came with the truck. He bought this truck about 10 years ago.

How hard or easy is it to pull the old one out of the block? Rubber mallet?

Mine was full length. I just grabbed the top end and rocked it bak and forth while pulling. Came out easily. Use the mallet to knock the new one back in.

Glad to see a happy ending on this thread.

I've been following along with interest. I've been messing with a couple of 964S YFs I rebuilt a while back and have been struggling to get either one of them to run right on my 216. I'm not telling you this to hijack Otto's thread- when I run out of ideas I'll post my own thread to solicit advice. Page 11 gave me some more info and things to look into and check on top of other info in this thread and others.

Just wanted to say I appreciate the knowledge base and discussion here that helps us quiet ones who just read and follow along most of the time.

Hehehe, he said, happy ending...

Yes the truck is running as smoothly as it was before the carburetor croaked.

Start a thread with your specific questions. I'm sure someone here will be able to solve your problem.

I own a lot of different vehicles and work on friends' vehicles for fun. I follow various forums specific to certain makes and models even if I don't have a specific problem that I need to solve.

I literally learn something new every time I work on a vehicle or read forums.

Today I finished installing coil/strut assemblies on a 2004 Lexus LS 430. It's the newest car I've ever worked on in my life. It belongs to a friend of mine. It sure was a lot more involved than changing shocks on a '66 Mustang!