Originally Posted by befumo
But why would this affect idle speed? Seems to be something funky going on. It refuses to fast idle properly as well.. even though it is set to 1700. (Changed it with the EGR valve hose plugged, second cam etc). It will start up to 1700 then start increasing towards 2,000 rpms.
Went through and checked all vacuum hoses today, all good.
re: Manifold heater: Didn't mean to check the operation, but check the mounting for vacuum leaks. These are known to cause intermittent vac leaks, and are rarely checked as they aren't visible without a mirror.
If your carb won't hold a steady idle when warmed and properly adjusted, check the return springs (2), and check the throttle shaft bushings for wear. Worn shaft bushings will cause the throttle to stick partially open at idle when warm.