Looking for vacuum schematic for 81' C10.

[PStansb]

Hey All -

I'm looking for a vacuum schematic for a 1981 C-10 with a 305 in it.  I've got several hoses that go nowhere under the hood (just bought it last week) and need to know where everything goes.

At least some of these are obviously affecting performance, because when I plug a couple of them with my finger, the motor RPMs increase and smooth out.

Just out of curiousity, what do most of the vacuum lines in these series do?  I hear people all the time say "I just pulled all those vacuum lines out.", but no one seems to know how to trouble-shoot/fix them.

Thanks in advance!

Paul E. Stansberry, III
Edmond, OK

[Lt.Del]

Yeah, i would get that fixed soon. You have to be robbing half your horsepower and fuel efficiency.

You should have a silver rectangular sticker under your hood by the hood latch somewhere, next to your radiator. This would be the vacuum schematic.

I am very familiar w/ 1979's which I am sure are very similar, if your's is still stock.

Can you describe where these hoses end up or begin?  Depending on where they go to, i can probably tell you what the other end connects to.

Vacuum lines go to your carb, to your TVS (thermal vacuum switch) on your thermostadt housing, they go to your distributor for advance, a hose behind your carb on the intake goes to your auto transmission modulator, One goes to your EGR valve.  ONe goes from the intake to your air filter housing to control that valve in the snout.  Don't forget about the lines going to your charcoal canister that attaches to below the carb (gas vapor return lines).  You have one going to your pvc valve on the valve cover.

It all depends on which line you are talking about.  Do you have a digital camera you can take pic and post?

I believe the Haynes manuals have the vacuum schematics also.  

SgtDel


 

Edited by: SgtDel at: 12/25/05 8:43 pm

[PStansb]

Thanks for your help.  Yes, I'm attaching 3 pictures below that I need help with...  It doesn't appear that anything under the hood has been modified from stock, if that helps.


This one comes off the distribituor and T's off to go....  where?  Then continues on to go...  where?


This little metal tube comes off something down towards the transmission.  I have no idea where it's supposed to go.


This one is probably the worst.  This is at the front of the motor, in what I THINK I have learned is the TVS on the thermostat?  There are three lines that appear to be supposed to come off of that, but as you can see they don't go anywhere.  Here's a close-up of that spot...



I appreciate all your help!  I just want it to run smoothly.  It's running now, and isn't killing me...  but I plugged the T and the loose hose off the distributor and instantly the motor smoothed out noticeably and the RPMs sped up.

Thanks!

Paul E. Stansberry, III
paul@stansberryweb.com
Edmond, OK

Edited by: PStansb at: 12/26/05 11:19 am

[PStansb]

OK - I think I got it.

I started examining the TVS and found that one of the 4 plastic nubs was broken completely off, so I bought a new one, installed it, and then re-routed the vacuum lines according to the schematic on the label under the hood (Thanks SgtDel for pointing this out, if it were a snake it would have bit me) and then tried again.

Starts, idles, & runs much smoother now.  Next will be plugs, wires, and distributor.

Thanks!
Paul

[DnStClr]

That Sgt dell is all right ain't he? Paul, did ya get the small metal line figured out?  
Was it the early fuel evap line going to the tvs? Either that or it is the line going to the trans for torque converter lock-up.