carburetor questions (1957 original carter)

OK all of you carburetor gurus, I have a few questions..... the kit has a few parts that I didn't find in the carb, do I need them? if yes, where do they go?






Also, the new needle and seat are substantially different than the old one. The spring on the new needle makes it impossible to adjust the float. my old one does not have the spring or the long snout on the seat. Will the fuel pressure going into the bowl overpower the spring?



last question.... how many turns should I open the idle screw to start out? I have it an one turn now.

thanks,
mike

 

Question #1: On which model YF are you working? Look at the vertical rib on the body, just behind the linkage. Stamped there should be the model number.
Question #2: From which vendor did you get a kit without instructions?
Question #3: Do you own a Vacuum Gauge and/or a Dwell/Tachometer?

OK. Moving on.
Photo #1: On the left is a fuel flow Check Weight Needle.On the right is a check ball weight. Look down the barrel of the carb, near the top with the carb oriented as in Photo #2. At the three o’clock position you will see a tiny hole. That is the accelerator port. Immediately to it’s right is a vertical passage. Depending on the YF model upon which you are working, you will insert the Check Weight Needle or a check ball and the weight.
Right side of photo #1; Refer first to Photo #3. Do you see that big ol’ sheet metal screw , (which has no business being there?) in the throttle housing? The big silver plug is supposed to go there. Don’t worry about the other two plugs you’ve shown.
Photo #2: DO NOT REMOVE this metered orifice. If you want to poke something in the calibrated hole to make sure it is clear, do not use wire. Use clean, dry compressed air.
Photo #3: Aside from the aforementioned improper sheet metal screw take note. There is another improper sheet metal screw inserted where it doesn’t belong. The plugs should be removed to allow a thorough cleaning of the carb, inside and out. These tools are good to have for this purpose.

Still in #3; The Idle Mixture Screw should be turned in until it lightly bottoms out in the passage. The turn it out from 1/4 to 1 1/4 turns.
Finally, Photo #4. Without a view of the float itself so I can determine which type it is, and not knowing the model of YF this is, it is hard to say, other than if you can’t set the float to it’s proper height, and again we don’t know which carb this is so we can’t tell you. Ultimately I am concerned about a pair of vacuum leaks where the sheet metal screws are located.

Hope this helps.

 

Question #1: On which model YF are you working? Look at the vertical rib on the body, just behind the linkage. Stamped there should be the model number. Sorry, I can't find any other numbers on the carb except X 1538 on the bowl area and I don't think those are the numbers you want.
Question #2: From which vendor did you get a kit without instructions? I got it from CSE offroad, I believe it is from Omix-ada though
Question #3: Do you own a Vacuum Gauge and/or a Dwell/Tachometer? No.

OK. Moving on.
Photo #1: On the left is a fuel flow Check Weight Needle. On the right is a check ball weight. Look down the barrel of the carb, near the top with the carb oriented as in Photo #2. At the three o’clock position you will see a tiny hole. That is the accelerator port. Immediately to it’s right is a vertical passage. Depending on the YF model upon which you are working, you will insert the Check Weight Needle or a check ball and the weight.
Right side of photo #1; Refer first to Photo #3. Do you see that big ol’ sheet metal screw , (which has no business being there?) in the throttle housing? The big silver plug is supposed to go there. Don’t worry about the other two plugs you’ve shown. Cool, will be glad to get that PO crap out of there.
Photo #2: DO NOT REMOVE this metered orifice. If you want to poke something in the calibrated hole to make sure it is clear, do not use wire. Use clean, dry compressed air.
Photo #3: Aside from the aforementioned improper sheet metal screw take note. There is another improper sheet metal screw inserted where it doesn’t belong. Should there be a plug in there or left open?


Finally, Photo #4. Without a view of the float itself so I can determine which type it is, and not knowing the model of YF this is, it is hard to say, other than if you can’t set the float to it’s proper height, and again we don’t know which carb this is so we can’t tell you. Ultimately I am concerned about a pair of vacuum leaks where the sheet metal screws are located. There is a lot of wear on the bottom flap linkage, but I did not detect any vacuum leaks when I sprayed the area with carb cleaner earlier. Here is a pick of the original float setup.... maybe this will provide you with more info.



Thank you very much for your help.

 

Many threads here on all this in the past - search the archive.

You really need to have a good set of YF instructions and specs - again, they can be found on line if you search.

Many vendors sell generic YF kits, as used on many different vehicles - but JEEP applications are different. Be sure you have a JEEP kit.

I won't try to cover all the details here, but the spring loaded needle valve is an example. It was intended for "rough service" Jeep applications and has a entirely different float setting specification than YF street applications with a rubber tipped needle. Also the Jeep valve seat should have a smaller orifice than the 'civilian' YF to reduce fuel pressure on the needle, reducing flooding on steep grades or rough travel.

 

"Photo #3: Aside from the aforementioned improper sheet metal screw take note. There is another improper sheet metal screw inserted where it doesn’t belong. Should there be a plug in there or left open?” That port is for a vacuum fitting (vacuum advance distributor) or screw-in plug and should be 1/8”, fine thread.
From what I see of the adjusting tang resting on the needle, you have adjustment room. Bend the center tab (tang) to achieve the proper float setting of 5/16” as measured placing a 5/16” gauge (shank of an unused drill bit will work) across the upside-sown top (as you have it in the pic) to the float. As close to exact is what you want.

PeteL is exactly right. A search of the site should yield the instructions you need. You definitely need a vacuum gauge and a Dwell/Tachometer.

 

For some details when rebuilding a YF, check this Mike's carburetor yf rebuild you-tube:

I recently rebuilt my YF using one of Mike's carb kits, and was at first befuddled about the kit's replacement parts for the two parts related to the float. I didn't have a spring-loaded pin in my YF, but in a phone conversation with Mike, he explained to me about using the spring-loaded pin (you seem to have that under control). However, when it came time to calibrating the float, I had to add an additional washer to the left-hand side component in your Figure 3 to bring the float tang to proper specs (without bending float parts). Upon reassembly, the engine started up easily. But now I have some 'hunting" (surging up and down) during idle, so maybe I have a leak. I'm glad that reply#1, Scoutpilot, pointed out that the YF screws and plugs you illustrate may be a leak-source. I'll check for that sometime this week. Not much information on the internet on carb-idle 'hunting' (most of it for small engines), but what I did read points to fuel-air mix too lean, or a leak.

-- ronnie

 

I have one YF driving me nuts with severe 'hunting' and I've run out of ideas after removing and rebuilding it several times. I will be very interested in whatever info you come up with.

 

Will do, PeteL. In the little experimenting I did this weekend, before reading about possible leak as the cause, was to turn the mixing screw way out -- probably 3-4 turns -- and that seemed to quiet down the hunting somewhat. But that can't be the true solution to the problem because the screw is now far out of normal operating range. Then I ran out of time to keep working on the idle. I'll look into it more as I have time after work this week.

 

sweet, this is great info. I was not sure where the check weight needle went (even though scoutpilot did a good job explaining it to me)
Photo #1: On the left is a fuel flow Check Weight Needle.On the right is a check ball weight. Look down the barrel of the carb, near the top with the carb oriented as in Photo #2. At the three o’clock position you will see a tiny hole. That is the accelerator port. Immediately to it’s right is a vertical passage. Depending on the YF model upon which you are working, you will insert the Check Weight Needle or a check ball and the weight. Evidently, my carb did NOT have these parts in it.
My original problem was it would not idle and would stall out when I applied the brakes. gas was just swirling around the carb like a toilet instead of spraying down the venture. the accelerator pump was as hard as a rock.
I learned 2 important things from the video... where the check weight needle goes and that the choke linkage makes the idle go up. My linkage was set so that it was not doing anything to the idle.
My first test (missing the check weight needle) it is idling better, but it is 'hunting'. I will install the check weight needle today and I will let you know if that corrects the hunting..... maybe you guys are missing that part too?

 

small update. Inserting the check needle caused it to not run at all. Long story short, I figured out that a check ball was placed under the main jet by a previous owner. Everything is now set up properly, but now I have vacuum leaks everywhere ( the gaskets that came with the cheap kit are too thin to seal properly. I have a new carburetor rebuild kit ordered from mike's carburetors, so hopefully this will fix my problems.

 

Update: The Mike's carburetor kit was no better than the cheaper kit. Actually, it was worse! The cheaper kit came with springs and a lot of metal components. The only thing that the Mike's kit had was the correct needle and seat...... and directions. Unfortunately, the directions suck. Oh well, it is back together and running better..... not good. I think I still have a vacuum leak at the throttle linkage. I will buy a bushing kit and see if I can fix it. Otherwise, I think a new carb. is in my future.

 

If I am correct, rebuilding with new bushings will require a having a reamer or using a machine shop. Expensive.

I found it more practical to buy a NOS carb.

 

you are correct, but NOS carbs are very hard to find. most rebuilt carbs are no better than mine. I found couple of vendors online that offer a 5/16 bushing kit (with reamer) from $40 to $70. I will try my hand at reaming it myself.

 

Be sure to measure the throttle shaft for size. Use a micrometer and you will discover that it has worn into an ‘egg’ shape, along with the throttles bores. Bushing may not be enough. New shaft is .3125”. Below .310 and you will have a vacuum leak. PeteL is correct in that you will need a 3/8” and a 5/16” reamer. How do you intend to install the bushings? If you have any questions just ask. I do two or three a week here. WO’s and YF’s.

 

I used the bushing kit from Carb junkies in Georgia. I used a dremel and ground the back side of the reamer so it turned from t ok push through reamer to a pull through reamer. So that you could use the shaft of the reamer as a line up too.
Here is the bushing kit
Carburetor 5/16 Throttle Shaft Bushing Repair Kit 8 Bushings 16 Screws Reamer

And here is the write up for the reamer modification.
StudeM15A-20: Throttle Shaft Bushing Install

 

I got the bushing kit from Carb junkies in the mail this afternoon. I couldn't wait to run out to the garage and pull the carb (I am getting pretty quick pulling and replacing the carb now) I bored it out with no problems using my drill press with the base of the carb clamped to a large piece of angle iron.
I have it all back together, but it got too late for me to work on it anymore, so I will have to see how it works tomorrow.

 

Update: I am starting to hate this carb!!!!

The tally so far:
2 rebuild kits - $50
worthless mechanic - $150
reaming kit - $50

Problems found and corrected:
vacuum leaks - all fixed
float had small leak - all fixed
accelerator pump not seating flat at bottom of carb - fixed
missing needle weight - added.

It now idles 'better' but not good (I can get it to idle with the choke completely off for the first time). fuel mix screw is turned out about 1 turn.... anymore than that, the engine stumbles when accelerating. At cruising speed (45-50mph) it won't hold a set speed.

Some things that I am focusing on now: A Mikes carb video on youtube shows how to check that the check weight ball is sealing. it says the accelerator pump should stay down if you hold the ball seated at the bottom, but mine slowly rises. It looks like the small ball inside the accelerator pump is not rising up and completely closing the hole in the accelerator pump. It also looks like the ball & weight combination sits down in the hole too far, so I am wondering if I should be using the weight needle?
There was a LOT of crud in the float bowl...... I mean a LOT! Looked like mud or something. I am wondering if a passage is still 'partially' blocked with stuff that won't blow out? (I did not remove any plugs during the cleaning process)
I am also looking for someone who has a dwell meter and timing light to help me sort that out too.

I can't believe I am so close to diving this thing and I am stuck at this last step. oh well, motor on.

 

My friend, I’m going to be perfectly honest with you. You cannot hope to succeed in this carburetor venture without the proper diagnostic tools. Please post photos of the vertical rib behind the linkage so we can determine which carb you have. Float setting is problematic if we don’t know which carb it is and which type, Viton or brass, needle you are using. Better still, send it to me and I’ll take a good look at it. I can see that you’ve already spent too much on it, so I’ll make you this deal. I’ll fix it for free if you pay the shipping.

 

Got the jeep in the hills for the first time yesterday, in the mud and had a blast!!! What a little climber this thing is!!! By the way, the Weber 2-bbl downdraft works perfectly--uphill, downhill, on side slopes, etc. I figured it would, since the float chamber is rather large. For those of you who would like to get rid of your carb issues and get more hp on your top end, 280 bucks out the door includes the adapter for the engine, too. The company is Redline, (sorry, I don't have the link handy) and you can also order jetting kits from Weber Carburetors Carbs 40 DCOE 45 DCOE 32/36 32/34 Jeep. Top-End Performance 818 764-1901 . The carb has a progressive mechanically opened secondary, so you don't have to worry about vacuum opening it. Looks nice, too. I think the carb number is K-553. I did the calc's on the F-134, with a formula I got from Timgr and determined that I needed 155 cfm carb. This is a 150 cfm carb and works very well.