The Stovebolt Site Forums The Shop Area Engine Shop Carter YF carb getting too much fuel

Howdy Jon, so I’ve taken a picture of the float as I’m adjusting to 9/32”. In the image it’s parallel to the carb surface which I understand to be a good starting point if you don’t have specs. Anyway we’re a long way from 9/32” still and so I certainly feel something is amiss. Any insight? Also the metering rod number is 75-837 if my eyes aren’t fooling me.

Compare the arm on the float below to the arm on your float.

Adjustment is done by bending the tab on the float arm, not the arm itself.

Jon

I’m just reading some of the posts. I’m not a mechanic nor a carburetor specialist. I’m not even familiar with this particular carburetor (though I’m getting ready to buy one). One sure way to verify if the needle seats & stops the flow of gas is to remove the top so you can see the top of the float in the bowl. Let the gas flow, push down on the float and verify if the needle works as it should. I’m probably way off here but just offering my 2 cents! Best of luck!

When the top plate of the carburetor is removed, the float, needle and seat go with it. So this suggestion will not work. Thanks though.

Jon the two floats are different. I do suspect the float is incorrect for this model YF. There is no way to obtain 9/32” without really cranking it down even more than what it is.
The actual shape of the float is the same but the arm is different. It’s hard to explain but you probably already know what I mean.
Do you happen to have a 2100s in stock?

Chinese fake float. Good luck. I faced the same problem with my Mustang. The solder probably isn't even real and will melt in gasoline causing your float to sink.

Bob - I sent you a PM.

Also, if that carb has 2100s stamped in the side; perhaps you would consider sending it to Jon G. (the other Jon ) to sort it out for you.

The metering rod number you posted is a 216 rod. Sounds like a Frankencarb, but maybe it can be sorted cheaper than buying another.

Jon H.

Even if it is a Frankencarb (only 26 more days until it wanders your neighborhood looking for free candy), I might be able to sort it or at least help it do a better job...if I have enough of the right Carter parts left. Contact me with PM if you want me to try.

I am wrestling with a similar problem. So I was looking through my acquired settings charts and noticed that there was different settings for the needles that do not have a spring loaded top. That setting is 15/32. Looks to me that the carb we are taking about in this thread has the spring loaded type.

Be careful here!

The very early 1950 Chevrolet replacement YF carbs (787s) used the W-1 fuel valve (25-33s with solid needle) and float 21-117s. THE FLOAT SETTING ON THIS CARB ONLY WAS 1/2 INCH!

This arrangement was modified AFTER A FEW MONTH, BUT STILL 1950 to a 25-195s (spring loaded) fuel valve and float 21-122s. The FLOAT SETTING WAS CHANGED TO 5/16 INCH!

The 5/16 inch setting was used with the spring loaded fuel valve on all versions of the 756 carb, 787sa and 787sb carbs, all versions of the 788 carb, and all versions of the 789 carb.

All versions of carbs 964, 965, 966, 967, 2100, 2101, and 3211 used the spring loaded fuel valve with the 9/32 inch setting. Carter did NOT offer a solid valve for these carburetors.

It is important to KNOW not only which carburetor, but which version, and then acquire specifications for that specific carburetor.

As a general rule, the generic aftermarket instructions, which come in a FLAPS kit, are quite useful.......................TO PLACE UNDER THE PARAKEET'S CAGE!

Jon

Okay makes sense. So the next observation is that the there’s two types of spring loaded types of caps that fit into the needle. And should the spring clip one be the preferred option.

As long as the overall length from the top of the valve with no tension to the thread is the same, either work well.

The original Carter plunger looked like a miniature golf tee, some of the aftermarket plungers are just a round shaft.

Either works.

Jon.

Jon here are the images I couldn’t get to load on the PM:

It appears the float is dropping too far, Bob. It should be 1 1/4". Please check and let me know.

Bob - compare that float to the picture of the correct float I posted earlier. Your float does not have the two tangs used for adjusting float drop. As Jon G. stated above, the float drop must be set. Yours is too low, which allows the valve to be placed in a physical position it doesn't like.

Jon

Jon and Jon, I changed the short tab to reduce the drop. Reassembled and ran it. So far so good. No excess fuel surging out anywhere. I’ll take it for a test drive a little later to see if it’s going to starve out anymore. Taking a bike with me this time! It’s the pits to walk back home… 😜

So I have it running and idling. While it’s parked the engine runs good. I can gas it and rev the engine with no problems. But just driving out of the driveway under a load it stalls out as if starving for fuel. I can’t seem to figure it out.

I'm traveling right now and thus am operating from memory only but my first thought is you're not getting quite enough fuel at this point. Jon (Carbking) mentioned that's not the proper float but it seemed to work ok and when I looked at this I didn't have a spare float of the proper type. The drop level is slightly less important than the level from airhorn to the float, but if the float level distance between the float and airhorn became less than 7/16 or 15/32" it might be out of range. Let's see if the other Jon chimes in...

Yesterday I picked up a Carter 2100s, put in a rebuild kit and installed it on the truck. Got it running and it seems my issue with fuel surging out is gone. Over the last few day I made a couple discoveries:
- there was an in line fuel filter between the frame channel behind the battery box. It was full of junk.
-the fuel shut off on the tank was also full of junk. Both problems were likely causing the starving issue unless idling.
-the tank had been cleaned up and treated but they (previous owners) didn’t do anything else between that and the pump.
The timing is also off due to the clamp bolt being loose.

So there were many things contributing to my issue’s. Now I need to figure out how to do the timing on a 53 235 engine and what the basic setting is for the screw at the base of the carb. Currently it’s 1 1/4 turns out.
I have a timing light so just need to know the process for timing. Yes I’ll look it up but if anyone has any tips?…….
Bob

Do you have the shop manual?

Otto, no I don’t. I’ve only owned the truck for an 5 months.

You can usually find them on ebay for around $20-$30.

Here's a whole bunch of them.
https://www.ebay.com/sch/i.html?_fr...chevrolet+truck+shop+manual&_sacat=0

Unless the engine is either just rebuilt (less than 500 miles) or almost worn out (burning a significant amount of oil), then 3/4 turn to 1 turn on the idle mixture control screw is a good starting point.

1 1/4 turn will probably SEEM to idle more smoothly, but waste gas at idle, and foul plugs.

Jon.

The engine is a 235 in a 46 half ton so I am not sure those shop manuals will help.

It will give him the necessary information to work on the mechanical aspects of his engine and transmission, including tune up procedures. He'll need a '46 manual for the rest.

If he determines what year the engine is he will be able to purchase a manual better suited to his engine needs along with the manual correct for his body and chassis year.

Didn't he say it's a '53 235 or do I have this confused with another thread?

Otto: Did you notice that the 4th ePay add down in your link above was for a "48-53 Chevy Truck Shop Manual" and had a picture on the cover of the V8 engine. Don't know if I'd trust that book.

You are correct Otto I re-read post and he did say 53 235.

Bob,

Just a helpful note here that until you can acquire the shop manuals that will help you work on your truck, many of them are freely offered for you to access and use from Keith Hardy's web page here.

You have access to not only the various shop manual, but owner/operator manuals, parts books and a whole slew of other Chevy resource info. Just make sure when you are searching that you look at the correct book or resource document for what part of your truck you're working on.

If you're not sure which manual might apply to what you are working on, come back and ask the question in the on-topic Shop Area Forum and we can help you out!

Also please don't forget the GM Heritage Pages have a wealth of information on GM trucks (and cars).

https://www.gm.com/heritage/archive/vehicle-information-kits

Thank you for all of the input. I don’t have a dwell/tach meter so I suppose I’ll need to round one up. Also need to find the little ball on the flywheel and paint it white. I think I can get it close enough until I have all the correct gadgets and books in my hands.

So today:
Float levels set, fuel pressure at 3.5 psi, Timing set, idle mixture screw 1 1/2 turns out.
It idles nice but won't take any fuel and falls flat when I give it the onions. (Vice grip garage lingo, sorry)
I can ad a 20 second video but it won't upload. At least from my phone.

Are you saying it bogs/dies when you goose the throttle? What happens when you move the throttle rod gradually?

Bob,

Per Jon's (carbking) earlier reply to your questions:


It sounds like instead of decreasing the idle mixture setting (you said it was previously 1-1/4), you have instead increased it to 1-1/2 which may lead to some of your falling flat issues.

That being said, there are may variables that could be causing your issue. You mentioned you rebuilt the 2100s. Did that include a complete disassemble, cleaning and blow out of all ports and orifices?

Beginning to wonder if their is a blockage in your carb somewhere affecting your operating circuits beyond the idle circuit.

Just in case it may help, here's a link from "carbkings" site Carter YF Service that may be of some use in understanding your carb.

I’m thinking back to my overhaul of the carb. I took a lot of time to ensure all passages and orifices were clear and the carb was spotless. But, during assembly the kit contained a gasket the same periphery and footprint as the accelerator pump diaphragm. I installed it below the pump. I did not see one on the old pump when I removed it. Could that have been an issue? Giving too much open area below the accelerator pump?

Otto it does the same. Gradual movement to increase engine speed works briefly and it will die out if I hold or continue.

I made the mistake of installing that extra gasket under the diaphragm. (From what I have read, that gasket is for some obscure engine which allegedly calls for it.)
The installation of that gasket did not cause any issues for my 235 whatsoever. I left it in there until the next time the diaphragm needed replacement.
If I were you, with all of these mysterious fuel delivery issues, I would buy a new gas tank. A Spectrum gas tank is around $200 the last time I bought one. I would pay twice that for one and I can be a cheapskate. Piece of mind is priceless.

My truck also has a Carter YF carb. The fuel pump pressure at the carburetor is 2.5 psi.

Your 3.5 psi is at the high end of the range. What kind of fuel pump are you using.

I have the factory pump in there. I removed an electric pump I had put in there for troubleshooting purposes.