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I recently replaced a cracked exhaust manifold on my 56 Chevy truck. Now that I've got everything back together, two weird things are happening. The first is that the engine sticks on high idle. You can punch the accelerator and it will come back to normal, but it always sticks again when you step on the gas. The other thing that's happening is that while the choke operates normally, it has no effect on the engine at all. I did have the carb apart to replace springs and seals, etc. I even took pictures of it before i disassembled it to make sure I got it back together right. Had it off again this morning and everything looks right but I'm wondering if I haven't gotten something wrong.
As far as the sticking idle is concerned, I don't think it's the linkage hanging up because I've tried several different springs in several different configurations and the result is the same. You can push the throttle linkage back with your hand and the idle will go back to normal, so it's sticking in some way but i don't think it's the linkage interfering with anything. The choke cable is attached correctly and operates normally. It just has no effect on the engine. Do I have a spring backward or not attached correctly? Something tells me it's something like that.

When one fools with the manifolds, it is important to lightly snug up the inter manifold bolts first, the tighten each manifold individually, then tighten the inter manifold bolts. Use of brass nuts guarantee future removals will go smoothly.

Ed

Thanks, Ed. I did follow those instructions when I reassembled the manifolds. I have to think this issue is related to the carb, though. Once again, the symptoms are: Sticks on high idle. And the choke, though it works mechanically, has no effect on the engine. I had the carb apart and I think I might have gotten something wrong when I put it back together, though everything looks right.

joflanigan Take your linkage off at the carb,accelerate by hand see if it returns to idle. If it does look for tight place at belcrank or floor board. If not look for tightness in carb. Do you have a spring under the accelerator pump ? That helps it return,also spring under the metering rod piston. Is the fast idle cam lever free to return ? Is your return spring vertical and attached down at pan rail ? Not binding the linkage. Watch for carb gasket binding throttle plate,is your thick insulator below the carb in there ? Good Luck with your hunt !!

OK, thanks. Good idea. I will try disconnecting the linkage and see if it still hangs up. I do have a spring under the accelerator pump. Also under the metering rod piston. I do have the throttle return spring in a vertical position and hooked to the edge of the oil pan. Everything seems clear under there and I don't see anything binding although it occurred to me that there might be some binding where the throttle rod comes through the firewall. I have to check that out.
Also, I do have the thick plastic insulator under the carb.

I'm not sure about the fast idle cam lever. Is this supposed to be under spring pressure? There is a spring wound around the choke assembly on the outside of the carb that seems like it's not doing much, which makes me think I might have it hooked up wrong.

joflanagan Yes there is a return spring on that idle cam,you have to wind it a little to get on the shaft flats then put your washer and screw on.

I managed to solve the sticking accelerator problem. Like someone suggested, the accelerator pump in the carburetor was hanging up somehow. I managed to get it so that it operates freely. Not sure what the issue was but something was making it hang up. But my choke still does not operate correctly. It has no effect whatever on the engine when cold except to kill it. I've attempted to attach a photo here. DOn't know if it will come out. It's a Rochester model B with a manual choke. WHen you pull the knob out, i understand that the valve at the top of the carb will close and restrict air flow and mine does that, but is anything else supposed to happen? If you can see the photo below, does it look like the linkage is correct? That's pretty much exactly how it came out of the truck. The small lever at the top of the carb contacts the longer piece (which i think is the throttle lever) but it doesn't move it very much. Could that be the problem? The weird thing is that it worked perfectly before i removed the carb.


choke linkagehttps://www.flickr.com/photos/192738021@N08/?

https://www.flickr.com/photos/192738021@N08/?[url=https://www.flickr.com/photos/192738021@N08/?][/url]

Joe, why are you not using our photo hosting process. Instructions are in the left margin of every page.

Sorry, didn't notice that. I looked elsewhere on the site for how to post. Might have gotten dated info.

Be sure the choke is closing all the way. that was my problem.

Looks like the idle speed screw is screwed in all the way.

http://www.tocmp.com/manuals/Carbs/Rochester/B/1951-B/MCarbRoch1951-B_0002.htm#1048577

The choke does close all the way. But as far as I understand, a choke closed all the way stalls the engine, so I'm not sure how that would be connected. And yes, the idle screw is almost screwed in all the way. I never touched it. That's just where it lands when the engine idles at about 500 rpms. I have noticed it, though, and think it's a little weird.

I can't bring up a photo of it. I would like to see one. When the choke is pulled out the choke plate closes & the lever on the side moves enough to kick up the idle speed a little. I'm thinking the ledge in the carb is not seated in the hole in the lever. The screw is tightening it down on the ledge. Thats the best I can explain it. The lever should move back & forth easily & the spring should pull it back.
George

Yeah, it seems to me by looking at it operate that the choke lever doesn't kick the lever on the side over enough. It barely moves it. When you say "the screw is tightening it down on the ledge" do you mean the idle screw? Anyway, while the choke valve closes, there is no increase in the idle like there was before I took it apart.

Never mind. i re-read your post and i understand what you're saying.

Joe -- Look in the column on the laft of this page. The very bottom item is our image posting guidelines/instructions. They are as easy and up to date as I know how to make them. If they do not work for you, let us know and we can help you debug whatever the issue might be.

Most of my stovebolt browsing takes place on an iPhone and I couldn’t figure out what folks were talking about with the instructions on left side of page. It wasn’t there. At all.

There a little “II” symbol in the gray bar at upper right of page. That expands things and will reveal the left column with the photo instructions. I feel less crazy now that I understand what you all were saying.

Joe's photo is on flicker:
Carb

JW! Thank you for the II tip!

Thanks, John.

JW ... Wow. I never knew about *that* ... I can't wait to tell peggy you guys have figured out how to turn her Announcements column off ... hehehehehehehehehehehehehe!



I wonder if Paul knew about this ... ???

Guess the mobile version of site collapses it? People kept preaching about how easy it was to post pictures. All I could recall was the old way where you had to host on a server somewhere and then link them. I was too lazy to go find a site to host my pics

Back to trying to help with the carb....


I would back that idle speed screw out as shown in the picture I posted earlier. Then set the idle mixture screw by turning it in until it's seated and backing it 1 1/2 turns out. The aim is to set the adjustments back to factory settings. If you cannot get it to idle properly from there, the carb needs a rebuild kit.

I can't put my finger on it but something is wrong with the position of that lever. Back the big screw & washer out to make sure it is seated right on the ledge.
George

I’d agree with that based on the picture. If a guys takes the air horn off, it’s easy for that fast idle arm to get on the wrong side of something and nothing works right.

With the idle speed screw all the way in like that, the throttle arm shouldn’t be hanging below “horizontal” like that. At least not with the two different Rochester B’s I have here to look at.

I agree something doesn't look right there. I definitely got something crosswise when I took the carb apart to rebuild it. I have a spare to compare it with and the position of the lever looks the same. BUT there is a LOT more tension on the spring to the fast idle arm. I'm wondering if I haven't wrapped the spring around properly. It feels kind of loose, like maybe it needs one more wrap. As far as the idle speed screw goes, I never changed that. It's always been like that and the truck has run great for over ten years. Also, the choke worked perfectly too, until I removed the carb. Anyway, I'm out of town right now but will get back to it when I get back. Thanks, everyone, for the help.

I think this is going to wind up being really obvious. And really dumb.

When you take one of those apart, that lever has a tendancy to turn up side down. You have to hold it back a ways while putting the air horn back on.
I agree, its something simple.
George

I remember having a similar issue when I rebuilt mine. You’ll figure it out. Just have to keep fiddling.