Carter Yf And Idle Problem

Hello-

This is likely the dumb question of the day, so thanks for any input in advance.
1966 CJ5A won’t idle once warm. It hunts and stumbles, and I have to give it fuel to keep running.

I know vacuum leaks are common and will be doing a rebuild. That said, I’m wondering if the attached pic shows an issue with the fast idle arm. Where contacted by the idle speed screw, there’s a hole that renders my screw setting ineffective, as the screw tip just goes in the hole. Is this hole by design, or worn by the screw over many years? It seems like an easy fix to weld up the hole and grind flat.

Thanks again.

Edit - despite a file size of only 788KB, my photo is too large to attach, sorry.

 

Disregarding the idle screw for a moment, your symptoms may be related to wear around the throttle shaft - if so it would benefit from re-bushing. Not part of an ordinary "rebuild."

 

A good carb shop can re bush loose shafts, a common problem with old carbs including YF'sI. had to have mine done. Depending on where you are, you may have to send it out
Vintage Jeeper and Old Jeep Carbs are options.

 

Thanks - I hadn’t considered that. I’ll check for play. I assume someone sells a kit, or carb shop only? A newly refurbished YF is $300, so a rebuild plus those bushings would approach that cost…

 

I recall a kit but it requires reamers and so on, IIRC.

 

I’d appreciate it if someone could take a look at their Carter YF and let me know if the idle screw contacts flat surface on the idle arm, or if it goes into a hole.

 

Here's some notes I got back when mine was rebuilt:

https://flic.kr/s/aHBqjA9jxK

 

Thanks for this info. It mirrors what’s in the Haynes manual. On your first page, figure 7, it shows the fast idle arm and adjustment screw, as you’ve marked. Like Haynes, it doesn’t show the surface that the screw contacts.

I’m pretty sure that hole shouldn’t be there at this point. It effectively allows the throttle to retract completely, thereby reducing rpm’s to the point of poor idling.

 

I would never rely on a Haynes or similar. Too much 'generic' info combined from different models.

Get a specific FSM.

 

Neither on mine, screw contacts the edge below the tang that contacts the housing. Below the hole made for the tang to bend over.

20230524_175437 by Joe with a jeep, on Flickr

 

Exactly what I was looking for, thanks much.

 

I’m in S Cal also. Did you use a place around here, or send it out? Someone referred me to El Monte Carb. Those online places look like they do pretty good work, albeit with a shipping and time delay cost.

 

You may have found my vacuum leak. There’s significant play on that shaft. I also had some gas leak out around there when playing with the throttle (engine off). Sounds like a rebushing is called for?

 

I started with send mine out to a specialist...
It came back with the shafts fixed but set up for a F head so ran like chit. Another Wagon buddy took on the chore and got it dialed, even hand made a metering rod. Havent heard lor found a shop nearby but El Monte is close.
Where in the oc are you?

 

I’m in Tustin.

 

Silverado

 

Nice. I’ll message you if I get it going well enough to brave Saddleback Mountain again.

 

Near the old LTA hangers.

 

Lighter Than Air...

 

Sorry in advance to bump this for what is likely a dumb question.

I’ve had my carb “rebuilt,” but it still idles poorly when fully warm. I don’t think they did the throttle shaft, so I’m wondering if there’s a definitive way to tell if it’s too loose? I talked to a pretty knowledgeable guy around here who indicated that the YF’s were always fairly loose, so I’m unsure as to how tight it should be.

Question - with the engine off, and hand application of throttle from the linkage, should gas drip out of the carb from the end of the throttle shaft? That would seem too loose to me, but again, I don’t really know.