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

So maybe a rebuild shop cobbled it together from whatever parts they had? Does that mean a rebuild kit might not have what's needed?

My father's shop was a Carter authorized distributor in Nashville during the 1950's and 60's. He also told the story about those million replacement carbs, with one added detail- - - - -the one millionth carb off the production line was gold plated, and presented to the CEO of General Motors!
Jerry

Otto - Carter 964s carbs are not expensive, nor or they rare.

There are probably 8~10 on ebay at any given time.

Given your posts, I would suggest it might be prudent to just buy another core. Get the vendor to show pictures on the stamped number, as well as the number on the metering rod, and other casting numbers.

My Dad used to have a saying about "spending good money after bad".

Jon

Most likely it is Jeep-Willys-AMC.
The reason I says this is because of bits of info starting here (https://forums.g503.com/viewtopic.php?t=247067).
A YF 738SA with a 6-1658 air horn assy.

While searching I was able to find 3 different carburetors identified as Carter YF 4002S.
The first picture has a 6-1658 air horn assy.
The second has a 6-1657 air horn assy.
The third has a 6-792 air horn assy.
I included a small picture of the bowl casting # on each.

Rebuilders must have a barrel full of used cleaned carburetors parts labeled "use for Jeep".
They close their eyes and reach in and grab a part. It's all Jeep so it's good.
Using Carter specification sheets to check each part for correctness takes too long (is it break time yet?).
The customer will never know.

Does that likely mean that this carburetor isn't jetted properly for the Chevy?

What differences would there be? Could this one be rebuilt to CHevy specs? Or as Jon suggested, better scrap it and buy another one.

Could this one be rebuilt to Chevy specs?

YES! IF you are independently wealthy, and don't care if you stay that way!

I no longer do restorations, but if I were, I would charge you more just for the research alone than I would sell you a fully cosmetically restored 964s!

Just poked around a bit. The castings numbers you posted are not ALL correct for any Willys. So one would have to check first if the castings will even work properly together. Then one would have to pull the Carter prints, and determine how each casting is machined, and re-machine for the 964s. One would then have to change ALL of the calibrated parts.

With the necessary research, to do it right would require 2~4 WEEKS labor, and while as a kid, I used to work mowing yards at 50 cents/hour; I doubt you will find many carburetor rebuilders that will work that cheap today.

EDIT: NONE of the 964s carbs on ebay are mine, not grinding my own axe.

Look at the second line in my signature block!

Jon.

Hahaha! Got it.

Rebuildable cores of the 235-sized YFs are fairly expensive. YF Cores for the 216 are more common on eBay and seem to have much more reasonable asking prices. You could also look for one in the swap meet section here.

Now that we know you have a hybrid of some sort…might as well just get a 964s, rebuild it, and know that you have the right thing. Sounds like your engine ran well before all this.

Yes, the truck ran very well, idled smooth and quiet. You could turn the idle down so low you could see the individual fan blades.

Then, while it sat for a month or so while I was working on other things it suddenly had all these problems. After eliminating electrical issues it became obvious that the carburetor had failed.

Looks like I'll be buying this core ( https://www.ebay.com/itm/154868031282?hash=item240eda9f32:g:A0YAAOSwJTBh8GAH ) and a rebuild kit from Jon.

She’s a beaut, Clark.

Before you buy a core.

Check the pictures out closely and ask the seller questions.
The throttle may not be stuck but there could be too much play in the shaft.
These carburetors are old and may have a lot of usage which means wear.
Don't mean to scare you but how good are you at doing a rebush? Got the machining tools?
Notice the picture of the air horn fuel inlet looks like sealant but could be stripped threads (a common rookie mistake). I would ask.
Also notice the trash or bugs deeper in the inlet. Wonder about the insides?
Such are the woes of the humble carburetor rebuilder.

Yes, I saw that inlet with the possibly bunged threads and crud in the back. I have no intention of rebushing anything since I don't have the tools or the desire for that.

I sent the seller a message earlier today but haven't heard back from him, yet.

If anybody knows of a good core or rebuilt unit, let me know.

The threads in that airhorn are stripped and not usable.

Call me tomorrow.

573-392-7378 (9-12, 1-4 most Mon-Tues central time).

Jon.

Roger that vector, Victor!

Does this story have a happy ending?

We'll see.

I've purchased a re-buildable core and kit. I'm confident that it will all work out.

Just FYI, I did not buy that carb on ebay. Seller replied that the threads weren't bunged and and that that was sealer in the picture. Nevertheless I wasn't interested.

I'll post pictures on the progress and result.

A little levity while we wait on the follow-up.

"vector, Victor".

Sorry guys and gals, I can't help but laugh. Maybe it's just me being silly.
It reminds me of the Star Trek movie where navigator (and security/tactical officer) Chekov's accent get's in the way of trying to pronounce "victor", "victor" to the ship's computer.
It sounded like "wicktor", "wicktor".

Anton Yelchin was a great actor and I hated to hear that he died in a car crash when he was only 27 years old.

Back to the carburetor.

That's actually a line from the movie, Airplane!

The sealer in the threads is worse than if the threads were damaged!

The threads may be repaired by drilling, tapping, and using the next size thread, or simply machining a fitting with a slightly oversize thread.

The sealer will likely have clogged the idle jet, the idle passage, and who knows what all else.

When I was still restoring carbs, a carb that came in with sealer in any location (fuel inlet, gasket surfaces, etc.) to be restored got an automatic 2X on the price quote.

Sealer of any kind around a carburetor is for amateurs, or for sales folks hawking their wares!

Jon

Hahaha! you're right. I never use sealer or tape on any fuel line threads.

If that's "sealer" in those threads, the seller must be named Pinocchio, and I'll bet his nose is a couple of feet long!
Jerry

I've begun disassembly and cleaning of the new core. I'll post some pictures when I start to put it back together.

Is there a trick to removing the accelerator pump diaphragm? I removed the 4 screws and figured it would just pull up but it doesn't budge. Probably just stuck in place after many years but I wanted to double check so I don't damage anything.

Yes the diaphragm can stick badly. I pour a little alcohol in the fuel bowl to cover the pump check valve then work the pump shaft up and down.
This pumps the alcohol in side the pump. Let it sit a while then try again later.

Be careful not to warp the pump housing by prying too hard with a screwdriver.

Just checking. You did first remove the metering rod, springs and lever parts?
Be carful not to bend the metering rod.

Yes, I removed all that. I haven't pried it and don't intend to.

Don't pry nor force it. Let the alcohol sit there a few hours. Then you can reach in with your thumb and press in different directions on the pump bonnet (cover). Usually that will let it come loose. The diaphragm is made of rubber and it bonds to the float bowl and the bonnet and sort of acts like glue.

I had to boil mine in various concoctions before the pump would come free.

It's soaking in ChemDip Carburetor Cleaner now.

In the immortal words of Homer Simpson, "Alcohol is the cause AND solution to all of life's problems!"

The alcohol soak did the trick. Moving the plunger up and down broke the rubber diaphragm loose.

I'll check the diaphragm cover on a sheet of glass I have on the work bench.

Now, shouldn't this pump connector link just pull straight up and out? This one stops before the bottom end gets into the bowl. Again, I don't want to use undue force to remove it. Anything I need to know?

I see from the picture that the throttle assembly is removed. Good.
Push the link back down and make sure it is straight (not twisted) on the end.
Also the passage (slot) can get filled with a little corrosion.
Spray a little penetrant inside and work the link up and down.

Notice the orientation of the small dust seal (metal and rubber part).
The need to know becomes apparent on reassembly.

Dust seal? Where's that?

Sorry. I have the YF 2100S on the brain. The earlier model YF carburetors didn't have them.
Just ignore me. I'll put my dunce cap back on and go stand in the corner.

I think a lot of folks called that the anti-slosh seal. I've been replacing them in all of the older YFs I rebuild. Originally that seal was to keep gas from sloshing up and out the slot into which the lifter link fits when the vehicle went around a corner or was on a steep hill. The problem we have today is ethanol laced gasoline will "creep" up the float bowl until it reaches that area so we have 2 ways gas can dribble out and down the lifter link. If anyone needs one of these (and the metal retaining piece that was used in conjunction with it), please let me know.

I wondered about that pump link. Not exactly a hermetically sealed unit, is it?

I have a question about the new needle and seat compared to the old one. why is there such a major difference in these two parts? The old needle is triangular rather than square. It also has a spring included that the old one did not have. Where does that spring go? As you can see the brass seat is completely different. The orifice is much larger in the new one, too.

Remember that this carburetor is not the hodge podge Willys affair but rather a 684 YF from the Carb Shop.

The new mixture screw has such a small head on it compared to the original one, I worry that the spring might be to large and not fit correctly under the head of the screw.

Any thoughts on these things?

If your rebuild kit is from Jon H then the needle and seat is NOS. You are in good hands.
The difference you see in the used parts are that past rebuilders used the wrong parts.

The spring is like a shock absorber for rough terrain (farm truck bouncing around in a rough field) to prevent flooding.
Jeep has the same design.
The tube extension in the seat is for fuel sediments to settle rather than lodge in the needle and seat.

Is the idle mixture spring new or old?

YF 684S? Maybe you have a different model?

Thanks. Yes, the carburetor and kit are from Jon. It's a 684S

The idle mixture spring is the original.

Where does the spring in the needle and seat package go? On top of the needle?

Like so.
Don't compress the spring when you set the float distance.

Aahh, thanks a lot. I wondered what the little rivet thing was for.