Quote:
rgrinder wrote:
other possable ways of "fixing" the problem without a lot of brain damage are to use the vacuum advance port for the distributor to also supply the trans. or get a vacuum canister like many of the GM and Ford cars use on thier cruise controll systems, these look something like a juice can with vacuum fittings on them, built into them is a one way valve to allow vacuum to be stored and allow enough to be there when it is needed.
The vacuum signal available at the distributor vacuum port will not be any stronger than at any other point in the manifold, so this will not offer any advantage.
Using a vacuum storage tank will also help to confuse the trans as vacuum storage tanks normally use a one way valve to prevent the manifold gasses from entering the tank & lowering the vacuum value at higher throttle settings.
What this means is that when you floor it going up a hill, the engine works harder, but the vacuum modulator sees a high vacuum signal from the tank & hangs onto the higher gear for longer.
The vacuum modulator works like a TPS [throttle position sensor] or looked at another way, it acts as an engine load detector. This signal, combined with the rotational speed of the govornor produces a line pressure that controls the shift point.
With low vacuum [high load] the govornor needs to send a high pressure signal before it will upshift This means it needs a higher rotational speed at the output shaft of the gearbox. As you reach the top of the hill [or whatever] & the throttle setting it reduced, the vacuum signal increases & the upshift pressure requirement is reduced, so it upshifts.
A vacuum tank will screw this up even more than it is now. My suggestion is to do some research on your carb. If it is possible to use a slightly smaller venturi, then give it a try. The simple fact is that in its present state of tune, for street use, with this trans, the engine is over-carbureted.
Transfer
