Turbo 400 experts please step in....
 

69 Chevelle , 496.
3.42 gears.
2 things:
The 1-2 shift is waaay too early. I want to delay that. I don't think I'm going to get there with just modulator adjustment. How about reducing or limiting the vac. source?
Secondly , is it essential that the electric solenoid switch be connected..........because it currently isn't.

Re: Turbo 400 experts please step in....
 

There are several companies that sell governor weights and springs to move the shift points around . You are correct that playing with the modulator won't get it done . The kick down solenoid basically bypasses the modulator circuit at WOT only .

Re: Turbo 400 experts please step in....
 

I knew that if you saw the original post, you would have the answer, Russ. From what Pustelny tells me, there are very few people who know GM automatic transmissions as well as you.

Re: Turbo 400 experts please step in....
 

https://www.hotrod.com/articles/hppp...ing-turbo-400/

Had someone use this to adjust RPM

Re: Turbo 400 experts please step in....
 

Re: Turbo 400 experts please step in....
 

What is the modulators job? If it has little to no effect on shift timing , then why are they offered as "adjustable"? I've already played around with the weights , 2-3 shift at WOT is about 5800-6000....which is fine. Presumably , under WOT the 1-2 may be similar.
This post is about shift timing at part throttle around town driving though.It shifts almost immediately into second , part throttle casual driving.
Does the kick down have to be connected to increase lne pressure?

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How much vacuum do you have at the modulator? -Al

Re: Turbo 400 experts please step in....
 

Check the modulator vacuum like Alan said. Some factory metal vacuum lines had a restriction at the modulator end. If so drill it out. The governor has more influance on the 1-2 shift, the modulator has more effect on the 2-3.

Re: Turbo 400 experts please step in....
 

NOT AN XPERT -- but I was always taught to believe the modulator determined to an extent the "firmness" of the shift that is "hard or soft" --where as the governor determines at what rpm the shift is made--FED 387

Re: Turbo 400 experts please step in....
 

The idle vac is 10"
From experience I know if the mod isnt connected , it wont shift.
That being said I would think low vac would make it MORE reluctant to shift.
No one has addressed the kick down solenoid? IF I dont care about kickdown , then its not required to be connected.....somewhere I read where the solnoid increases line pressure in kick down mode?