ryanleiker

iTrader: (2)

I've done the vacuum modulator modification on my 4l80e.
I need to put in a check valve in the vacuum line from the motor to the modulator.
I've eliminated all visible/external rubber vacuum lines on my motor and converted them to nylon line with push-connect fittings.
I'm trying to put in a check valve for this vacuum modulator that doesn't use a hose clamp and hose barb.

What check valves/arrangements have you guys used on this mod?

forcd ind

iTrader: (7)

Are you running boost? you shouldn't need a ck valve-I used one of those TCI I think vents to blow out boost, but it was nippled.
If you use a ck valve, depending on how its installed, you would end up holding vac. against the mod, or not getting vac to it-think power booster for brakes, what the ck valve does

ryanleiker

iTrader: (2)

Yes, I'm running boost.
I understand how a check valve works.

The check valve goes in a tee off the main vacuum feed so that it closes under vacuum to communicate with the modulator, but bleeds off boost and doesn't damage the diaphragm in the modulator.
I also need to track down an orifice fitting, with, I believe, around .050" hole.

twinturbo496

iTrader: (2)

Make sure the cut down modulator seats correctly in the adapter. I added a chamfer so that it would seat right.

PBA

And I thought I was the only one who thought out of the box (adding the chamfer).

forcd ind

iTrader: (7)

Somewhere I have pressures written down with/without the mod. installed, the pressure readings were @ 1200 RPM for each gear-if anyone is interested I will post them-I think I was running the HD-3 man shift kit.

ryanleiker

iTrader: (2)

Here's what I ended up with. It's not pretty, but it'll get the job done long after I'm dead.
Important fittings: #3- jic .047" orific fitting, #7(top)- check valve

josh4ku

iTrader: (10)

MY new 4l80e from north texas converter has vacuum modulation. I didn't realize i need to install a check valve somewhere. shoot.

ryanleiker

iTrader: (2)

only if you are running boost