Originally Posted by tazzco
I thought a vacum is a vaum, but I made sure new hose was new and small clams to ensure they did not slip off. The vacum I have is located just behind the carb, I would say half way between the carb and distributor. There is no obstructions in the vacume, should there be??
nope. Vacuum is not vacuum,
The Vacuum feed to the trans modulator must be direct manifold vacuum. It needs to raise and fall with engine load (throttle opening) so the modulator receives the proper signal to control pressure inside the transmission.
One side effect of low or no vacuum is ''no upshifts''