Reply to "Aussie Cleveland vacuum routing"

Espen,

When the coolant outlet gets too hot, the vacuum "switch" or "tree" substitues manifold vacuum for ported vacuum. At a stop this has the effect of slowing down the idle speed of the car, with the intention of reducing the heat load on the cooling system .

Instead, what occurs is the circulation of coolant is slowed down when the idle speed drops, and the heat load INCREASES, because the retarded ignition timing makes the motor less efficient. More of the energy from combustion becomes waste heat instead of work. The result is, the motor has a greater tendacy to overheat.

Remove all the vacuum lines, connect the "ported" vacuum on the side of the carburetor directly to the "advance" side of the distributor's advance mechanism. It will work much better. Then adjust the distributor at idle, with the motor fully warmed up, to achieve the setting where the motor idles the fastest (this is also where the intake manifold vacuum will be the highest). Drivability, throttle response & fuel economy will improve. Your motors efficiency will be maxmized & therefore waste heat is minimized. The heat load on the cooling system will be reduced.

your friend on the DTBB