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Old 04-19-2006, 08:45 PM
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TH-400 auto trans. "Vacum needs?"

With a Turbo 400 trans., running a vacum modulater, what type of vacum source is needed for proper operation?
I wish to increase line pressure under hard acceleration, as compared to low rpm's and idle situations.

Do you want 15 inches of vacum at idle, then drop to near zero at wide open throttle? or do you want the vacum to increase with wide open throttle?

I'm not real sure on what a vacum modulater does with these older automatic transmissions, or how it operates. I know on my late model cars, the computer does it all, TPS sensors, MAF's, ect...,

How do you know if a vacum modulator is working correctly?


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Old 04-19-2006, 09:00 PM
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needs direct manifold vacuum. High at idle , low at WOT.
Dont worry how old you are... it is the mileage on your body that adds up.
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