hi

1978 Chevrolet Blazer , Manual , carburetor V8 350 Ci

when i starts the engine the RPM jump over 3000 and stay there , no matter i put shifter in gear or it's on idle the RPM stay above 3000 !

i have checked the Vacuum and carburetor and also Wire gauze !

now i don't know what to do !!!

any Idea ?

 

there is a adjustment screw on the carb for the idle. it may just need to be loosened. also make sure its returning all the way back to idle position. sometimes a vacuum line or other crap will get lodged behind it

 

That is a high idle. Check for a Vacuum leak somewhere. Intake gasket area, carb gasket are where I would start. The carb baseplate could be worn too causing the throttle blades not to fully close.