fake

Car starts have to feather gas to keep running. Day previous turned high speed idle to 77 L-82 specs. Idled fine 800 rpm Today hard start keeps wanting to die! Spark plug wires i ohmed out fine changed in let filter on carb , vacumn hoses attached and new, i just want to adjust timing after intake gasket repair! Removed and replaced

vince vette 2

When you adjusted the high speed idle did you have to turn it down or up to get it to 77 specs? You say it idled fine then at 800 RPM, do you mean when warmed up and in park or neutral? When you are having problems now is that only only when cold?

fake

Car was warm when turned up. turned up idle! Will not idle when starting have to feather gas or stalls out!

vince vette 2

Still not quite clear on whether the stalling is engine cold or warm. Assuming in park or gear, etc. But that aside, my '80 L82 did the same thing straight out of the factory and for years. I had the carb rebuilt when I got back on the road a couple years ago. Certainly ran better with the idle mixture screws now accessible and properly set. Note the factory settings are intentionally lean on many of the later 70's cars, not sure on yours, but if they have plugs preventing you from access them because they are plugged, then they are set very lean. But that isn't likely the issue.

On mine the fix was to bypass the distributor temperature vacuum switch (DTVS) between the carb and the distributor vacuum advance. That switch won't open until the the engine warms up, so you have no vacuum advance. It is there in order to reduce emissions when the engine is cold, but it makes it run like you know what. If the issue is only when your engine is cold and you have a DTVS I suggest bypassing it to see if that corrects the issue.

Rescue Rogers

Is the choke connected. Are you letting the car warm up at high idle for a few minutes before blipping the throttle to get the choke to release?

28buick

If I read your post correctly you haven't reset your timing after an intake gasket replacement. Sounds like your timing is too low and you had to increase your idle speed to compensate.

fake

Engine is stalling cold can not even get it to idle to make an adjustment now. Ran fine when i timed it idle was low so increased it and now this problem!

Rescue Rogers

If you can get it to run at 1000 rpm see if the timing is 36* at 2500 to 3000 rpm without the vacuum advance. If it isnt, adjust it up so it is and then see where you have a stable idle with the vacuum advance connected. If you can get it down to 800 rpm or lower check your vacuum to see if you need to adjust your idle mixture screws.They could be out of adjustment.

You could also just have a good size vacuum leak. If everything else is good you could take some starting fluid and just squirt a little around the base of the carb and see if the idle jumps up, that would be where the leak is. Check all your vacuum lines for cracks and make sure they are tight at their connections

claysmoker

Throw a vacuum gauge on it. Sounds like a huge vacuum leak to me as well.

vince vette 2

I'll go back to the basic question, how does it run when it's warmed up

MelWff

Sounds like you did a number of things at the same time.
The people reading this thread have to know exactly what the sequence of these changes were and exactly after what change did your issue start.

mortgageguy

Does a 77 have a dash pot or some call it a choke pull off?

fake

Timed it after intake gasket replaced. Idled a little low so increased the high speed idle on carb to factory 800 rpms. Idle nice then. Shut off car went to start next day and hard start would not idle , could not even get it warm kept choking up, Shut off car check all vacumn lines all new! Carb filter changed,, no leaks visual around intake. We have gas in tank ,spark plugs and wiring correct on HEI cap. HELP!

Scott Liggett

If you are only having to add a 100 or 200 rpm when you feather your gas to keep the engine running, then it is probably something simple, like a lack of timing or the idle mixture is a bit too lean. Since you say you changed the intake gasket, start with checking your timing. Bump up the idle speed screw on your carburetor to allow the car to keep running in order to check the timing. With the vacuum advance disconnected from the carburetor and the vacuum port plugged ( I just pull the hose of the vacuum advance pot on the distributor and shove a golf tee in the hose on that end) set the timing to about 12-14 degrees advanced. Then see if you can get it to idle around the 800 rpm mark on its own. If it is still needing to be feathered, and your carb has the idle mixture screws accessable ( I can't remember what year they starting plugging off the access to them), then turn the idle mixture screws counter clockwise a full turn to see if that helps.

You may need to reset timing and idle speed and or idle mixture to get the desired settings and tune at this point.

If you need to rev the engine to more like 1500 rpm to keep it running, then you probably have a vacuum leak somewhere after your intake gasket change.