Vacuum Modulator 1968 Mustang 289 w/ C4 adjustment
10

Asked by MSGKots Nov 28, 2017 at 07:27 PM about the 1968 Ford Mustang Coupe RWD

Question type: Maintenance & Repair

I just had the engine rebuilt and I have it reinstalled.  I added a new cam,
intake, 4bl edlebrook and heads.  Now the tranny shifts harder.  The
modulator and lines hold 20 psi of vacuum with no drop.  So, how do I make
adjustments to my vacuum modulator?  Specifically, I have not been able to
figure out how to get a screwdriver in the nipple.  Do I have to take the
modulator off, otherwise I have not figured out how to get to the screw.

3 Answers
39,075

beatupchevy answered 6 years ago

on the auto rebuild shows the performance intakes don't have as much vacuum and that's dictates the shifts more vacuum later shifts ,, it probably goes through gears pretty quick right ?, (early shifts) try going without the module ? ? ? a small screw driver won't get to the adjustment screw ?

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10

MSGKots answered 6 years ago

The position of the modulator in relation to the tranny crossmember makes it virtually impossible to get a screwdriver in. Wondering if anyone has a tip.

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