[A390GT]

I just replaced the intake gaskets on the 68 Catalina because of a bad exhaust crossover leak, after when I took it for a check out ride it wouldn’t shift out of first and When it did it felt like it was slipping or in neutral and would go back to first.
The vacuum hose for the modulator is connected to the port on the intake down in front of the quadrajet where it was before. I was going to give the modulator a Tappidy-tap to see if it’s stuck.
It’s got the right fluid level and shifted right last week before I swapped the gaskets…
Any thoughts??

[Scott Thelander]

you have the hose mixed up
vacuum modulator hose fitting is on the pass front of carb ...in picture 1... just out of view
looks to be a q jet...??

Scott

[A390GT]

Yes it’s a Quadra jet. I looked through my books and couldn’t find any vacuum diagrams… I thought the vacuum port on the pass side was for the air cleaner. I think Im using that one for the hideaway headlights..

[Kenth]

Switch the aircleaner hose and modulator hose and you´ll be fine.
The vacuum signal from intake runner #1 only is too weak for anything else than the aircleaner inlet motor.
Hideaway lamp goes to the Tee at rear of throttle plate iirc.

[A390GT]

I Swapped the vacuum hoses today and it still has the same problem. Any way to test the modulator?
And how hard is it to swap out? I have 2 other th400 in stock

[stevep]

Did you unplug the connector on the driver's side of the transmission?
The modulator comes off by removing the bolt holding it in.
1st, verify that you have good vacuum going to it.
You could also have a bad governor.

[A390GT]

I live in nj… I know I have a bad governor…

That said, I only had enough time to swap the vacuum lines around.
Hopefully today I’ll be able to get to looking at the transmission side of things.
But the last time I didn’t hook up the modulator I at least had second or 3rd. This is just slip until it bangs down back to 1st.