Y block high idle

I cannot seem to get my 239 y block to idle down. I nave tried adjusting the two screws on the back of the carb but they sem to have little to no effect. Would timing being off make the idle race? Are there other adjustments on the carb?

 

What carb? Is there no idle adjustment screw near the linkage?

 

It has the stock holly 2 barrel. I don't see any external adjustmens other than the two on the back of the carb.

 

Check for a vacuum leak.. Disconnect throttle linkage and see if throttle plates are closing all the way.. Check timming.. I'm sure there are others to look for........

 

There is a screw on the linkage at the throttle shaft,

 

I am voting for the vac*** leak. I went threw the same thing with my 292 a few years ago.

 

put your hand over the carb and if it idels up you for sure have a vacuum leak if it bogs the engine down or the engine dies id say you safe and dont have a major vacuum leack.

 

I don't see a screw on the throttle shaft... On the drivers side of the carb base there is a boss that is empty, should ther be something there? I used the choke to kill the engine a couple of times so I am thinking I am okay as far as vacuum leaks go.

 

After you find the idle adj screw, check the linkage for being too short. I read a thread where a neo mechanic adjusted everything on the car before finding the linkage was holding the ****erflies open.

 

There should be a seperate idle speed screw somewhere on the carb, though I don't know enough about this model to tell you exactly where it is. It will likely have a coil spring around the body of the screw to keep tension on it and help it to hold it's adjustment.

Does this carb have a dashpot on it? If faulty or misadjusted it could be holding the throttle open too much. Same for the choke pulloff if equipped with an automatic choke.

What about transmission linkage attached to the throttle? Improper adjustment could also hold the throttle a bit above idle. Check for interference with the carb linkage. Brackets, vacuum hoses, wiring, air cleaner base, anything not routed properly possibly getting in the way.

 

How about a return spring to pull the throttle plate lever and linkage,,,got one ?

 

just a thought have checked your timing lately?? should be set at 8 degrees on the lines on dampner , also have heard y blocks can vary and some run the best at 12 ....try checking it you may be to advanced thinking it wont idel down...

 

KINDA BEHIND THE AUTOMATIC CHOKE IS THE FAST IDLE ADJUSTMENT. IT'S HARD TO SEE AND HARDER TO ADJUST. lOTS OF TIMES THIS IS THE PROBLEM WITH HIGH IDLE THAT EVERYONE OVER LOOKES. OTHERWISE IF LINKAGE ADJUSTMENT IS OK, THEN IT'S A VACUUM LEAK. TAKE YOUR PROPANE TORCH(DON'T LIGHT IT) BUT WITH IT ON RUN IT AROUND THE BASE OF THE CARBURETOR, THE VACUUM ADVANCE ON THE DISTRIBUTOR AND ANYWHERE ELSE THERE IS THE POSSIBILITY OF VACUUM. IT YOU IDLE CHANGES NOTICEABLY, THAT'S WHERE THE PROBLEM IS.