[ChevyC102007]

I have the vaccum advance hose connected to the vaccum port located underneath the fuel inlet line on the left hand side of the carb. As stated this is the ported vaccum for the Rochester QJet carb (I.e no vaccum at idle but pressure increases with engine RPM's) from my research this is where it is on as near as I can tell all stock engines with Qjet carbs until the middle 80's when the switch to TBI tock place. The PO of the truck had the hose hooked to a constant vaccum sorce on the carb causing absolutely NO advance at higher RPM's. Just my 2 cents.