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Idle speed - Carb.

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Idle speed - Carb.
Hedgehog

Hedgehog

Always Off-Roading Jeeper
Posts
9,370
Thanks
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Location
Tucson/Marana Arizona
Vehicle(s)
-1975 Jeep CJ5, 360 V8, Headers, Duel Exhaust,T15 transmission, D-20 Transfer case, Twin Stick Conversion, Warn 8274 Winch
-1951 Willys Wagon, 4 cylinder, "F" head, little rust, very close to stock
Okay so the CJ failed it's emissions inspection. So I took it to a carb. professional and he did his magic. We passed the emissions inspection with no problem. But, now it idles between 800 and 1,000 RPMs. The idle speed set screw is beyond adjustment. I took it back to the carb guy and he adjusted it some with an idle speed at 650 RPMs. That was yesterday, this morning it was back at ~900 even after it should have been warmed up. Frankly I'm frustrated and looking for advice.

AMC 360 V8, standard Motorcraft 2150 carb, was rebuild less than 6 months ago.
 
Have you ck'd for vacuum leaks?
Are ALL the manifold bolts and carb base bolts tight?
Are BOTH of the idle mix screws turn'd out the exact same amount?
LG
 
Lumpy - Yes

Torx - That is a possibility. The Carb, guy said that if the problem continues I should take it off and bring it in to check the shafts for leaks. I thought they checked them when I had the thing rebuilt. That was part of the reason I had the thing professionally done.
 
Hard to believe that shaft wear would show up all of a sudden like that-:confused:
Wonder if your carb guy might have gotten some vacuum lines switch's around.
Confirm, you did NOT have this high idle issue till after he mess'd with your carb.
LG
 
I would be looking for a vacuum leak. you looked? keep looking. Are the throttle plates closing all the way or slightly off center. what is the timing right now.
 
Hedgehog said:
Okay so the CJ failed it's emissions inspection. So I took it to a carb. professional and he did his magic. We passed the emissions inspection with no problem. But, now it idles between 800 and 1,000 RPMs. The idle speed set screw is beyond adjustment. I took it back to the carb guy and he adjusted it some with an idle speed at 650 RPMs. That was yesterday, this morning it was back at ~900 even after it should have been warmed up. Frankly I'm frustrated and looking for advice.

AMC 360 V8, standard Motorcraft 2150 carb, was rebuild less than 6 months ago.
Click to expand...

Usually when a carb is adjusted to pass emmisions, the a/f adjustment screws are adjusted inward....less fuel at idle, less hydrocarbons in the sniffer. Anyway, if its an auto choke, have you checked the choke setting and looked at the fast idle screw to ensure its off the fast idle cam when warmed up? :chug:
 
I remember having to run the screws in as far as I could and keep it still running. I don't think a carbed '75 CJ with a 360 could pass in CA. but a AMC 304 could.
 
Ok Long shot. can you use a longer idle screw with stiffer spring?
 
Lumpy - I agree about the shaft ware, probably not an issue, but a possibility.

IO - I used vacuum port plugs from Harbor Freight, I was very careful to use the right size for each port, but one has cracked already. An inspection of the others is in order. The timing is set at 12*, I could back it off some.

Fast - I did ask about the choke and got an explanation, not convinced though. It does act like it's not coming off fast idle. Can you tell me where the fast idle setting would be on a 2100/2150?

Torx - This is a fairly fresh 360 from an 82 wagoner. Once the cracked vacuum plug was replaced it passed quite nicely here in Arizona, even with a high idle speed.

Dan - The idle screw is long enough, it's up off the idle stop. I've go two springs in addition to the one in the carb already. The Shop guy says that to much spring causes excessive wear on the shaft. I'm hesitant to add another one.

The shop says that I should remove the carb and check to make sure the throttle plates are free and easy to move with no gasket material getting in the way.
 
Hedge, the fast idle adjustment screw is located on the passenger side of the carb, a couple inches up from the bottom and approximately in the center. Before you adjust it, ensure the engine is warmed up, and the choke plate is completely straight up. You should be able to see if the fast idle screw is on the fast idle cam. When fully warmed up, it shouldn't touch. If it is, then turn the screw about a quarter turn counter clockwise, then bump the throttle and see if it no longer touches. Sometimes all that is required is a spray of WD 40 on the choke linkages as they could be dirty, or very dry, and sticking a bit.
 
Thank you for that information. The carb. is like new clean, but there might be something there I can't see, a dry lube shot wouldn't hurt anything though. It really does act like its hanging only slightly on something. I assume the adjustment is a flat sided screw driver slot for adjustment.
 
Hedgehog said:
Thank you for that information. The carb. is like new clean, but there might be something there I can't see, a dry lube shot wouldn't hurt anything though. It really does act like its hanging only slightly on something. I assume the adjustment is a flat sided screw driver slot for adjustment.
Click to expand...

I'm fairly sure its a flat head screwdriver slot. I would go look at mine and let you know but my broken axle jeep is outside....in the rain. :(
 
Hedge, have you found anything out yet? Is the issue resolved?
 
Ravenous information beasts .... :) With Halloween and an early morning vet visit, along with a couple guitars to repair, I haven't had much of a chance to investigate. After the Halloweeners stopped coming I did get the flash light out and check my carb for the fast idle screw. it is right where Fast described it to be, unfortunately it is also covered by the E-choke so I can't really see the cam. I believe I did figure out a way to tell if it's touching though. Information will come as I continue.
 
Hedgehog said:
Ravenous information beasts .... :) With Halloween and an early morning vet visit, along with a couple guitars to repair, I haven't had much of a chance to investigate. After the Halloweeners stopped coming I did get the flash light out and check my carb for the fast idle screw. it is right where Fast described it to be, unfortunately it is also covered by the E-choke so I can't really see the cam. I believe I did figure out a way to tell if it's touching though. Information will come as I continue.
Click to expand...

"early morning vet visit" I hope all is well with him/her. :confused:
LG
 
Not a big deal, we got a couple birds .... yes birds, a mini Macaw and a Pionus .... that were/are in poor over-all health, this was the first visit to the Bird vet. An 8:00am appointment and almost three hours waiting, a local Zoo had 2 birds and a bunny involved with some sort of an emergency visit that took priority. All in all an expensive visit for us and the bird.
 
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