Just rebuilt the motor, as some of you may know, 22r carbed (aisin), EB 268 cam, 20 over, does have a 4-1 header from where don't know, previous PO put it in. While trying to set timing (950) I can not get this thing to idle below 1500. It will stutter and stall. I did rebuild the carb a while ago as well. Float level seems a bit high, i think the level is just above the sight glass from what I can tell (if that matters). If I hold my hand on the air horn idle does go up. This is what makes me think vacuum leak somewhere. I did find a possible vac leak in the oil pan gasket (will fix that later) I solved that iissue by plugging the hose for the pcv valve. All the vac lines have been checked, double checked with vac diagrams and identical to the tee. The choke is a little messed up stays somewhat engaged. (where do i find a cheap choke for this thing). I did mess with the idle mixture screw a little, but moving that does not affect idle at all.

Any help is greatly appreciated. thanks.

 

Also seems like the distributor is getting vacuum from both line at the same time. Is this also normal?

 

The distributor will get vacuum from both lines some times. One of the lines is ported from the intake and the other should be ported from the carburetor. The two lines sort of work against each other: when intake vacuum is high, you get a lot of advance since that side of the diaphragm is getting vacuum from the intake, but when you open the throttle, the other port adds vacuum to the opposite side of the advance canister, pulling against the intake vacuum, thus reducing advance based on throttle position. This is why you have to pull and plug both vacuum hoses when setting the ignition timing on your truck.

Float level should be in the middle of the sight glass. If it's not, something is wrong, likely with the float or the return from the fuel pump to the tank has some blockage. If the fuel level in the float chamber is high, too much fuel will be released by the carb and the only way to get it idling properly is with a high idle. Make sense?

Get the float level right, then troubleshoot things.

 

I'll try that with the float level first, just still curious why i get a higher idle when holding hand over air horn, usually this means that the engine is running lean, most likely from a vacuum leak.

 

u may hav a vaccum leak at the intake gasket try spraying carb cleaner at all the gasket areas and see if the rpm go up then replace gaskets as need be

 

I hope not, brand new build, but its a possibility. maybe my valve lash is off?

 

well after some more trouble shooting I solved the "vacuum" leak.

turns out that it was not a leak.

the connector for the carb/choke was not connecting correctly. two of the wires were backing themselves out of the connector not mating with the female connectors, leading to the fut cut solenoid not energizing.

Now on to tuning the idle mixture and idle speed. woohoo.

 

are you going to address the high fuel level?

 

heyyy....he had the same problem im STILL having.........this is interesting..im gonna try to fool around with my plug and see what happens..

 

that's next. but should not affect idle at all right?

 

did you ever get this figured out???

 

The original problem was the plug on the carb not connecting properly. the spades were backing out of the connection and not allowing the fuel cut solonoid to get power. Still have that high float level yet though. havent gotten around to fixing that yet.

So yes vacuum leak solved.