I am stumped, and pulling my hair out and I don't have that much to start with. 292 Y block used rarely over past two years. Starts right up but stalls at idle unless manual choke halfway and idle therefore raised. New fuel filter, certain it is not bad gas, rebuilt carb, new intake manifold gaskets, no vacuum leaks, new coil, new plugs, dist cap and rotor cleaned, new coil, verified spark in wires, timing checked and good, timing chain in good shape, valve rods not bent and valves operating well. I replaced generator with alternator and that is operating well. new battery. Higher rpm it runs well. None of what i have done has changed the problem at all.

Please Help? I am losing my mind.

 

Same thing happened to me on my 223CI. Found out the linkage was out of adjustment. At idle, things were shut down 100% so when I pulled out the choke it would keep running. Now it idles smooth at 450 RPM. I'm running Mototcraft 1100 1 Brl. and I followed the initial set up that was explained by Mikes Carburetors on Youtube. I hope that helps.

 

Sure sounds like you've covered all the bases.

What carburetor? Just curious. I agree your symptoms point to a carburetion problem, but this can be deceptive.

You mentioned "no vacuum leaks", and not trying to doubt you, am wondering if you've hung a mechanic's Vacuum Gauge on the manifold. This tool is practically mandatory for both general old school iron diagnosis and engine tuning, to include carburetor adjustment. Not trying to cast doubt on your mechanical aptitude here, just that with four (4) posts we have nothing to go on. Maybe you sprayed Febreze around the gaskets and called it good, I dunno. We get some characters in the forums sometimes.

And manifold vacuum readings verify things for long distance armchair coffee drinking mechanics like me. It's Great Grampas Scangauge! OBD-Stoneage. I think they are $10 or so these days. Nod your head "yes", you want one.

Another angle that comes up frequently is the problem of slipped damper or balancer rings. The outer steel inertia weight on the balancer has the timing marks. When the rubber bonding ages and cracks the heavy steel ring slips off index and buggers setting the ignition timing, it will typically be 15° to 20° out, way, way off even though the light says it's perfect. If the damper on your Y Block has not been rebuilt or replaced it is guaranteed to be junk, by now.

When that happens, incorrect ignition timing, the manifold vacuum signal through the carburetor is usually very weak. The carburetor idle circuit is dependent on strong manifold vacuum and getting the idle mixture adjusted. Though called the idle circuit, it and the off-idle transition area is where a LOT of driving is done so it needs to be set correctly.

 

Thanks. I can keep the idle raised by using the manual choke (or throttle linkage adjustment) but the problem is I have to raise it way beyond idle rpm to (1500-2000) to keep it running. Holley 2bbl.

 

Thanks, I haven't used a vacuum gauge on the manifold. I have a vacuum gauge but not sure how to use it on the manifold itself, only on the one vacuum port from the carb to the dist advance.
Good idea on the balancer. The engine was rebuilt b4 i bought it 30 years ago and the timing mark has always been at least 10 degrees off (10 degree advance from mark to run right). I will look at that again. It's so far advanced that the vacuum pot on the distributor contacts the intake manifold and prevents further advancement.

 

Sometimes it's just a matter of the idle RPM screw and the idle mixture screws being improperly adjusted. A shop manual is advised, or carb manual. Make sure every carb setting and adjustment spec is on the money. This starts at verifying fuel pump volume and pressure, and "wet float height" in the carb bowl. All the little errors will start to stack otherwise.

Sounds like a 2100 carburetor. One bugaboo with high mileage carburetors is throttle shaft will hog out the holes securing it in the carb body and introduce a big ole air leak, this is impossible to tune around. Not saying this is your problem but it's something to check.

 

This is definitely at least part of the problem. Ignition timing. Been there done that. The balancer needs to be replaced (or rebuilt) It is no longer able to absorb any crankshaft vibrations either. This is important. At a certain RPM a crankshaft will reach what's called resonance. This is a bad thing without a working balancer, and can lead to cracks, or even a broken crankshaft. I'm sure it probably beats the hell out of main bearings too. Apparently the inertia ring will sometimes launch itself through the radiator or down the highway, things like that. Not pleasant.

For a field expedient it's possible to set the initial ignition timing without using a timing light utilizing a mechanic's vacuum gauge. Need a 3/8" NPT barbed fitting screwed into the manifold to connect the gauge, there's one right in front of the carb, since there is no manifold vacuum port on this type of carburetor. Currently in the pic there is an Ampco Vapor Lubricator plumbed into the manifold.

Sounds like from your description, the distributor itself is clocked wrong as well. After re-stabbing the distributor correctly try advancing the distributor clockwise (w/ vac advance disconn. and plugged) at 550 RPM (slow) for highest steady vacuum on the gauge, and then back off approx. 1/2 to 1" from that point. In Colo. depending, the highest vacuum you might achieve in a stockish healthy motor is only 14" or so. You don't live in Leadville do ya?

This will be very close to optimum initial timing for pump gas and should correspond to an actual 12° BTDC or so on the damper (when there is actually an accurate number to go by on the damper) When the ignition timing is straight the carburetor should respond nicely to adjustment.

Start shopping for a new damper. Powerbond makes a good one. I think Mummert sells them. Or it can be sent off for rebuilding.

 

Hey Tedster9, my mistake.. I lead us wrong on the timing issue. The numbers are very readable and it was another vehicle (buick) where the timing needed to be advanced ten degrees from recommended. This truck the timing is 10-12 degrees and rotor points at #1 cylinder. Distributor is stabbed correctly.
I looked at the throttle shaft and it is loose with a leak. Not really wallowed out but loose enough that spray carb cleaner raises the idle a fair bit. Carb is only 15 years old but it was a rebuilt. Holley 64-3055. I guess i'l throw a new carb on there.
You'be been a great help. I didn't think of the throttle shaft.

 

It's something to check for. The rebuild I bought had bushings installed for the fix. I think Mike's Carburetors has them, they are probably a standard size available anywhere though.

 

I had similar idling issues a few years back. Mine, however, turned out to be from ethanol gas eating into the carbs body. The carb had been rebuilt just the year before. It formed a white powder in the bowl. A little bit of the powder filled the idle ports and I couldn't get it to idle without choking it. Try removing the idle adjustment screws and blow some carb cleaner in the holes using the straw included. then try a little air in there too. put the screws back in and adjust. It ight help.

 

Update: Problem solved. I replaced the carburator and it now runs like a top. I did trace the problem to the fuel valve mount before I replaced. I had replaced the fuel valve when I rebuilt the old one but there was something screwed up with the mount for the fuel valve on the float bowl. Anyway, the new carb fixed the issue. It is an exact replacement for the one I had put on there 15 years ago and was a Autoline C709, which is a rebuild of a Holley. Thanks for all the replies. It really helped.

 

Sweet. We like pics here too! We won't take it badly if it ain't been warshed.