C4 vacuum modulator question

[MI-Bronco]

I just swapped out my intake and carb. It was EGR and I got rid of it (fortunately MI hasn't caught up with CA).

I still have my old C4 trans vacuum modulator with two vacuum inputs.

Probably a stupid question, but should I just replace the two line vacuum modulator with a one line - probably the green stripe version?

BwoncoHowie, thanks for your previous posts on this subject - only reason I can sound even remotely intelligent about this.

 

[67EB_in_619]

In my carb-no-egr-setup, I had a single green stripe modulator... not saying it was right but it fit and it worked... keeping the same setup with the EFI swap....

CAUTION: HIJACK IN PROGRESS!
... can I use a different modulator to firm up the shifts?

 

[flint_knapper]

some of the modulators have a screw in the end of them for just that, so you can adjust the shift point a little.

 

[TJK74]

I switched mine to the single port modulator. Mine is adjustable as well. been running it for about six year with no problems works great. The reason I switched was when I put the 351 in with the cam I have my shifts were all out of wack. Took it to the tranmission shop the guy popped the single port modulator in and with a few trips around the block we were able to adjust the shift point back to normal.

 

[BwoncoHowie]

With your EGR removed, you can run the red stripe modulator as long as you disconnect plug off the small port. The green stripe is a good all around modulator to replace the dual diaphram modulator but you will need to get the correct hold-down bracket. Until I have everything needed to convert it, the red mod with the small port disconnected and plugged is the method I am currently using. I did this by stuffing a BB in the hose at the upper end of the steel line and re connecting it . Thanks for reminding me to go to Ecology wrecking today.~bh

 

[76 explorer]

speaking of modulators. how the heck can you adjust it while its still mounted in the tranny? i can barely get the vaccume hose on and off using the tips of my fingers due to the crossmember being extremely close to the modulator. i havent looked at it in a while but i dont think i have but maybe 1 inch between the end of the vaccume port on the modulator and the crossmember

 

[BwoncoHowie]

speaking of modulators. how the heck can you adjust it while its still mounted in the tranny? i can barely get the vaccume hose on and off using the tips of my fingers due to the crossmember being extremely close to the modulator. i havent looked at it in a while but i dont think i have but maybe 1 inch between the end of the vaccume port on the modulator and the crossmember

I use a pocket screwdriver that has been shortened. If i had a camera I'd snap a pic of it. I have used a piece of welding rod with the tip flatened with a hammer and then ground square. then you bend a small loop in the other end so you can turn it. The adjusting screw is not tight but under a slight spring tension. From the factory pre adjustment do not turn the screw more than 4 turns in either direction. Start with 1 1/2 to 2 turns in then drive it and adjust as necessary. Use needle nosed pliers to disconect an reconnect the hose. hope this helps gotta go.~bh

 

[BwoncoHowie]

In my carb-no-egr-setup, I had a single green stripe modulator... not saying it was right but it fit and it worked... keeping the same setup with the EFI swap....

CAUTION: HIJACK IN PROGRESS!
... can I use a different modulator to firm up the shifts?

Firming the shifts is not it's primary purpose but is a side-effect of increasing modulator pressure. I suggest that if your shift points are where they should be then don't adjust the modulator. If you still need firmer shifts, modify the valve body or transmission internals. Drain the pan and converter and replace with a fresh sump full of type F,( 8-9 Qts), this will help to firm shifts as well.~bh

 

[76 explorer]

gotcha.... im assuming screwing it in would lengthen the shift points correct?

 

[BwoncoHowie]

gotcha.... im assuming screwing it in would lengthen the shift points correct?

You assumed correctly. Screwing it in, increases modulator pressure, this in effect will make the shifts later and firmer. Screwing it out will do the opposite. Remember the 4-turn rule. ~bh

 

[76 explorer]

thank you very much