"two orifices in 3-way connector"...? (1 Viewer)

Nov 22, 2009
hey all... 78 stock 2F FED...

i am dialing things in on the rig... just had it manifold and oil pan gasket replaced, hooking up vacuum lines again and i am revisiting the "two orifices in 3-way connector"...?

this appears in the Emission Control Repair Manual on the schematic drawing...

is this important....?

is it holes in the vacuum line....?

having a little trouble high end power...
May 3, 2009
It's basically a tee. There are several pictured if you look closely. I have a few that came with my truck but they were in a box so knowing which one went where was, well, pretty impossible so they're not currently hooked up. (One is a little larger though.) I think they just regulate how fast the vacuum and/or air pressure equalizes on each side as none that I have are "one way".

Notice that the tee you're asking about passes through another tee which connects the atmospheric vent on the Evap system VCV and to the single filtered air source on the air cleaner. The loop of vacuum hose around the clean air source for the smog pump is also connected to the vacuum lines from the VSV to both sides of the distributor advance/retard canister. I'm guessing that the idea is for each vacuum lines to the distributor to get back to atmospheric pressure as the computer (through the VSV) sends vacuum to each half of the canister at the appropriate time so there's no fight between retard and advance signal.

This is the best pic I have showing the tee you're asking about (not my truck). Consult the schematic in the 78 emissions manual for the federal model to see if you can determine what each orifice does. Sorry I can't be more helpful. Post up if you figure it out.
78 Bay.jpg

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