I am trying to adjust my shift from 1500 rpm to 2000 rpm, and everyone says to take the vacuum line off the vacuum modulator, and turn a screw inside. Is this picture of my vacuum modulator? If so, notice the leaking fluid? There is a metal line running from the intake manifold (where the rubber vacuum line hooks up) down to within 3" of this thingy, and then a short piece of rubber hose bent in a 90 degree bend. It is very brittle, and is leaking now that I touched it. I need to replace this hose. Is this where the adjustment screw will be? If so, do I have to drop the tranny mounting bracket to get to it, or lift the rear of the trans up? It is right there behind the brace. Should I replace the entire unit while I am down here? If so, is this the thing everyone talks about as being "A" or "M" or some letter designation? and finally, if so, what letter do I need to order? Too many "if so"s in this question. :confused:
if you have fluide leaking out of the line the mod. is bad. they can be a "boy dog" to get out and in. replace the hose also. that is where the adj. screw is...(small screwdriver)..frank...
go buy a new one that is adjustable. inside where the vac line goes should have a small adjustment screw. take current one as a sample. uusally push in style, green stripe . if has 2 vac ports (late model) then get push in w/green stripe. only hook up line that has manifold vac. plug other line.
This is what came off...appears to have no screw, at least as far as I can tell, and a yellow stripe. O'reilly says they have the green stripe with adjustable screw for only $9.99...does that sound right?
OK, now I bought it and wanted it to shift around 2000, rather than the 1500 stock, at slow takeoff. So, I turned the screw 1/2 turn "tight" and installed it. refilled the trans and took it for a drive, and no difference. How much turning will adjust the shift to what rpm? Is there someting else wrong with my setup... I have the vacuum line coming out of the back of the intake manifold, split to the modulator and to behind the dashboard for the heater box controller. Can I share these, or does the modulator need it's own vacuum supply? Anything else maybe wrong?
If the mod is not getting enough vac, shifting will be very hard and high rpm. So if all is smooth, you have enough vac. The screw should be turned in little at a time until you have the shift you want. Dave
You did remember to put the little pin (in the picture of your old modulator) in the new modulator didn't you?
very good question I left mine out once...long time ago..... *just put a manual valve body on it and forget it Sorry, had too, thats the racer in me
Yeah, put the pin in and it actually shifts a little sooner. I ended up just driving it manual, since I hate it shifting at 1400 rpms. How much is "a little at a time"? half a turn tighter, full turn?
i,m impatient. if it's no where near where i want to be i'll screw it in a lot then back it out. but that's just me. mine goes to a vaccuum block attached to the manifold.
I ended up having to crank the screw about 5-6 full turns in. Then it got to a point where it wouldn't shift out of first (at all, as far as I know, I didn't go over 4000 rpm in the neighborhood). Finally got it to where it shifts around 2000. Once it got to the point where it would shift again, it was very fine tune adjustments, like 1/8 turn at a time, otherwise it would quickly go back down to 1400 shifts. Had that car jacked up at least 12 times, then a jaunt around the block. All the neighbors began to laugh at me just driving in small circles. I may have to back off a little since when I gun it, it doesn't shift until 4500 or 5000, which is where I shift by hand when I race. Also, on moderate takeoffs, the home-made shift kit i made really cuts the back end loose. Funny thing is, when it shifts at a higher rpm, it doesn't do the 2-3 flare anymore, or at least barely noticeable. Was that flare due in part to a faulty modulator?
