Vac lines

[tychain99]

I just finished a little winter project i wanted to do, Have not been on here since I parked the car in December after it started snowing here in CT.

Had some parts powder coated, and put new in new silicone vac lines and manifold boots.

I replaced the vac lines one at a time, took one off, cut the new one to corresponding length but there is one line behind and under the intake box, I cant figure out where it goes..

Help?

[Danglerb]

To the air pump diverter maybe? Does it come from a V fitting on the head?

[tychain99]

from a T fitting that is connected to 2 fuel pressure regulators.

[riber.bentsen]

You need to flip your flexi-intake-tubes around The solid pieces should be directly above the timing belt covers. There is a hole in them that fits over a small tube...

[Guest765]

I don't know how different the intake and vac lines are on the early engines but those fuel regulators (dampers) absolutely need to see vacuum from your intake or the car isn't going to run right. One of mine got bumped loose and the car ran like trash until I hooked it back up

[topfuel67]

Don't forget the vacuum line above the cat for the trans. There's a metal line coming from the pass side and then a 2" piece of hose and back to metal. This was the most rotted one I found due to the heat coming from the cat...

[Mrmerlin]

on the picture with that really nasty coolant bottle cap, (yes you need to replace it now)
the black hose thats coming out of the firewall is a washer squirter hose.
Roger sells em they are inexpensive to use a factory part

[tychain99]

SO i took the intake / filter box off. Seems to give me a better idea of what is going on .. I also found a diagram... I have the 2 lines coming from the pressure regulators, but the line splits, and I do not know where the goes....

[tychain99]

according to the diagram it ends between the 2-3 intake tubes, but I am not seeing how. Maybe I hooked something else up wrong, but it seems to me, as I took each line off, i replaced one at a time to avoid this little issue.. going to be nice tomorrow, I wanna drive this hog!

[vandenham]

If I read the diagram correctly, it look like the line you are holding (t'ed off between the two fuel pressure regulators - marked #5) goes to the front of the engine to the pressure damper - marked #3.

It looks like this goes through a 4 way 'T' that is between the decelerator valve - marked #15 and the throttle housing - marked #12.

[topfuel67]

I have the same set up on my 81. I'll take a pic and post it this evening.

[tychain99]

Thank you both.. I will check in a few to see if there is anything up front which looks to be willing to accept this little hose.

and that pic would be awesome. thanks

[tychain99]

I see the 4 way in the diagram, this makes sense now.. however I only had a 3 way. I cracked this 3 way changing my plugs before, and replaced it, upon doing this, I def noticed there were some lines which had been spliced, perhaps my lines were not hooked up correct initially.. so that pic from a functioning car would be awesome.

[Guest765]

The loose vac line needs to be attached to your intake. I do not know exactly where on the early cars but from what I can see its not getting any vacuum from the other end going into the firewall

[topfuel67]

The lines from the fuel regulators go into the 3 way T. The line you have out then goes to a 4 way t under the intake runners. If you're looking at the 4 way from the front of the car the front one goes to the fuel dampner on the front of the engine. The rear one goes to the 3 way T where your vac line is. The one pointing to the passenger fender makes a u turn and then goes to a ddiaphragm on the base of the throttle body. The one pointing to the driver fender goes to a vac fitting coming out of the base of the throttle body on the driver side. In the second pic its where my finger is pointing. Hope this helps
IMG_20130412_161945_074.jpg Photo by topfuel67 | Photobucket
IMG_20130412_162129_859.jpg Photo by topfuel67 | Photobucket

IMG_20130412_162019_411.jpg Photo by topfuel67 | Photobucket

[tychain99]

Got it ! thanks, I had to get another T, I couldn't find a 3 way, so i just had to splice off and T twice.. much appreciated

[tychain99]

so it is back together, looks good, does not run nice... idles at 2000 rpm.. played with distributor, not a lot of luck there, any thoughts?

[Danglerb]

I did a long post on one of the other vacuum threads, but short version.

Throttle has a flat plate inside, when it open from idle the front goes up and the rear goes down, this creates "control" vacuum ports located with small opening just above or just below the front or rear portions of the plate.

Front port has vacuum at idle, as throttle opens the pressure goes up to air filter no vacuum at all.
Rear port at idle has no vacuum, as throttle opens the pressure drops to manifold vacuum.
Main port is far enough above the plate to always have manifold vacuum.
Big breather port goes to base of throttle almost no vacuum, just tiny drop from air going through air filter etc.
There is also a thermal vacuum switch on the 1/4 head that either opens or closes when it warms up.

[tychain99]

alright, I played with the idle knob on the front of the manifold. Before i started, start up rpm is 2000. It drops when put in reverse.

I tried to dampen down the idle with the knob in the front of the manifold, I got it down to 1000 ish and it made the motor sound weak, and it stalled out.

at start up rpm are 2000, it sounds to loud, and motor just does not sound right. sounds like is working to hard.

the only thing i changed was the vac line from the rear fuel pressure regulators. I ran that up to the side of the manifold, and spliced it in as a 4 way, can some one else check and see if they have a 4 way connection on the passenger side of the manifold?

[Bills928]

What the diameter size of the vac lines ?...... this is the next project for me