Too much vacuum

[Brian VT]

Any trick to getting the cap off the VRV? I tried for a while and I fear that trying much harder will break something.

 

[Big Bart]

Perfect. Thanks.
Good vacuum to VRV and a new modulator so I just need to sort out the in-between.
How much vacuum should be at the modulator at idle?

18-20hg, basically what the vacuum pump puts out. When the VRV is at say 70% of throttle it should drop to 8hg. (+/- 1hg) Ford says to put 1/2” block (.55”) between the IP throttle arm and the full throttle stop. Then set to 8hg, but that does not mean a high mileage IP and tranny shift where you want it. So it’s a way, but really more “gets you in the ballpark.” Then you can rotate the VRV valve.

So if it was me I would take my a/c vacuum pump (You can use a mighty mite hand vac pump, but it’s a pita to keep pumping it.), hook to the vac side of the VRV, then hook your standard gasser vacuum gauge to the other side of the VRV.
1) Check for full vacuum with the gas pedal at idle/rest. (Basically same vacuum reading on both ports. 1-2hg drop is not going to be a issue.) Put the VRV in the middle of its adjustment travel. Loosen the screws a little, move back and forth, set in the middle, tighten the screws. Now start moving the throttle, you need to see the vacuum suddenly drop to 6-9hg when you are say 60-80% full throttle. (It could do it sooner, later, but guessing it is not doing it at all.) If not you need to start adjusting the nut on the VRV till this happens.
2) I am not sure how many turns you can actually turn a VRV before it perhaps bottoms out or the top comes loose. So my recommendation is go up to 3 turns one way, one turn at a time. No results go back to where you started, then go three turns the other way. I think you get what you want to do.
3) You can also loosen the screws and push the VRV all the way towards the window (With a good one this is a late shift) to see if that little extra gets you where you need to be.

If you can’t fix then its bad, look for a used one or try the Nick Pisa one.

If you get it working, likely you can.

1) Now test for proper vacuum down at the modulator. You need to confirm the rubber and steel line is not plugged up or leaking.
2) If you bought a after market modulator most have a adjustment screw in them. (Factory Ford ones did not, I have a factory one, so no expert here.) It’s in the middle of the vacuum plug the vacuum line hooks to. Look to see if flat, philips or hex screw. So after you set the VRV to where you like the shift, you can see if you can fine tune using the modulator screw.
3) Hook everything up and go test drive. Do a couple shifts, pull over, and turn the VRV nut up or down to adjust. Do a couple times and you will get the shift point where you want it.

This is not as difficult as it reads. Feel free to message me with your phone number, I can set up a time to discuss when you are under the hood.

 

[Big Bart]

Any trick to getting the cap off the VRV? I tried for a while and I fear that trying much harder will break something.

Brian,

Can you send a couple pics? Let’s make sure you cap is on, not missing. (If missing you can see the nut under the head.) It’s not a hex nut, it’s round with slots as I recall.

My cap wiggles just a little bit, that is how I figured this trick out. I use both hands and 4 fingers to evenly pull straight up and wiggle off. It’s on there pretty snug. We should confirm yours is not glued on or something. It should wiggle a tiny bit

Also keep in mind the part is not working, you would be breaking the broken part if something happens. If it breaks don’t beat yourself up. It is likely 20-30 year old plastic.

With that said these are pretty well made except for the vacuum ports they have a tendency to snap off of the head.

 

[Brian VT]

It's the cap with the hoses going to it and has a sticker on it. It does wiggle easily. It just doesn't seem to want to lift off.
I'll let the engine run even longer in hopes of making the plastic less brittle and try again.

 

[Big Bart]

Brian here is a VRV valve missing the cap, perhaps yours is missing the cap too.

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[Big Bart]

The nut is the ring with the tabs above.

 

[Big Bart]

Here is one with the cap. That cap will pop off the head of the VRV. You can see the bottom of the nut under the cap in this photo. The big long circular holes are for adjusting the VRV, when it is in spec. Your is likely out of spec, thus why you need to access the nut under the cap. Perhaps someone already pulled your cap off. I get it, I was nervous I would break the head off. But it was not working so I had nothing to loose and everything to gain.

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[Brian VT]

Thanks.
Glad I didn't try harder. Never having done it I was also pulling up on the hose barbs. DOH!
I could only turn the nut clockwise @ 3/4 of a turn before bottoming out. I'll try diving it now but I'm thinking I need more than that 3/4 turn or the VRV is bad. I also have some room to adjust the whole body towards the cab. If that 3/4 turn of the nut helped at all then I'll try moving the body as a last-ditch effort before getting a new VRV.

 

[Big Bart]

I hope that works for you.

Maybe it’s bottomed out (Out of thread) down to the bottom. But as I recall you want the head to go up higher and release sooner. So try moving the VRV to full tilt towards the window.

Then go counter clockwise, as I do not recall which way worked for me. As I said the head going up causes the dump of vacuum sooner.

But something inside the VRV could be broken or stripped if neither way fixes it.

 

[Brian VT]

The original 3/4 turn clockwise didn't help so I turned it 3 turns out from bottom. I guess it was in 3rd before I got to 15mph (I wasn't even paying attention that early) and the shifts were almost undetectable. It may have even been starting off in 3rd. lol
So it turns out that clockwise gets it to shift later. Now I've got it dialed in and it shifts great. I had almost resigned myself to buying a new VRV. It's bizarre that Ford didn't mention that adjuster. WTH?
Thanks all!!!

 

[Big Bart]

I was surprised when I figured it out 30 years later. I was surprised no one else had, or if they had, posted about it.

My guess is that is how they were set to tolerance at the factory, then shipped to Ford within spec.

Hundreds of these valves were tossed in the trash because no one knew they were adjustable after the fact.

Glad you are shifting like a champ again!

 

[Brian VT]

I was surprised when I figured it out 30 years later. I was surprised no one else had, or if they had, posted about it.

My guess is that is how they were set to tolerance at the factory, then shipped to Ford within spec.

Hundreds of these valves were tossed in the trash because no one knew they were adjustable after the fact.

Glad you are shifting like a champ again!

You are the one that figured this out? Cool! And thanks!

I'm not shifting like a champ "again". It was like that when I got it. Today was my 1st day of normal/happy driving with this old girl. After getting the air leak ironed out and the tranny shifting properly I almost have a daily driver.
Just need to get the instrument cluster lights working so I can drive at night (and know how fast I'm going). I've got the cluster unscrewed/loose but it seems there's no play in the cables back there to let me pull the cluster out. I called it a day and cracked a beer and will research more on that job.
Thanks again for all your time.

 

[Big Bart]

I remember when I got my truck it was not using the VRV to shift. (I was having late and very hard shifts.) I thought no way the VRV is going to make that much difference but it does.

I have not pulled my cluster but if something is holding on, my guess is it’s the speedo cable.

But others can chime in to help you out.

 

[Brian VT]

Yeah. My plan next is to try to find out how to disconnect the speedo cable at the other end to give some slack. From what I've been able to dig up it connects to the transfer case.

Edit: Turns out there's enough slack down below that I didn't need to disconnect. Just shove some cable up into the cab.

 

[Austin86250]

Happy that the thread I posted helped more people than myself