Can anyone point me to some info on how vacuum is supplied to the modulator on an M-pump equipped car? I recently snagged one from the local p/p and it does not have a VCV on it,like the MW-pumps do. None of the gear on top of the valve cover was present, BUT the trans DID have a modulator of course...

I lost that link. Thanks for re-posting it!

Custom Vacuum System
 

I'll confess that I came to this thread late and didn't read quite all of it so this may have been addressed - but is so, I missed it.

Anyhow, I'm putting an '84 300SD drivetrain in an '82 S10 Chevy PU to be used as a Land Speed Racing vehicle. It will never see street duty and is trailered to the track. I posted a couple of threads in the "Diesel Performance" section if anyone's curious. I won't be using much of the vacuum system (no PB, no heat/air system, etc.) but I am retaining the MB transmission, the vacuum engine shutoff, and any other bits that you guys tell me are critical.

So -
- How do I plumb this monster?
- What vacuum readings should I see at the shutoff, transmission vacuum modulator, etc?
- Can I skip the pile of stuff on top of the valve cover or is that critical to transmission operation? (Sure would look better w/o that mess!)
- Any other input? I'm new to MB but a pretty experienced automotive professional (retired).

Thanks for whatever input you can provide.

Dan

I'm pretty sure, all you'll really need is to get vac supply to the vcv, properly, 13-15 in/hg....and have the vcv connected to the modulator thru an orifice restriction fitting.

http://imageshack.us/a/img20/8785/19811984.jpg

That will depend on the car. Can you specify?

The VCV of a MRSF pump has an input (vacuum supply) and an output (regulated vacuum). It also has a vent line on the side.

I dont understand, there doesn't appear to be anywhere to connect vac lines to the pump itself

I see the two bolt holes where a VCV would go, I guess thats how I would hook this up... this is an M pump isnt it?

http://imageshack.us/a/img824/483/boschmpump.jpg

Thanks for the diagram. That helps a lot!

Dan

That is a MW pump.

Any time Dan, I'm happy to help if I can. As far as the pump types, I guess I had to re-read on how to tell the difference.

without VCV ;)

.

The stock transmission doesn't have a locking torque converter...you will always be seeing a loss between the engine and transmission. I'd recommended swapping in a different transmission if you're building a race car.

You can ditch the pile of stuff on the valve cover.

Dang. The vacuum diagrams only go to 1985 on his site

Thanks so much for the great info