I have been wanting to try and clean up a bit of shade tree hacks done to my motor and first on the list would be the vacuum lines. I have a loud hiss I can hear over the engine but will stop when I put even the slightest bit of pressure on the brakes.

Looking at various diagrams (which are tough to distinguish honestly) and comparing to my setup, there looks to be a lot missing. But possibly not, just routed differently? Photo of my engine bay below shows as it is now. The vacuum advance looks to hook right up to the carb which I was mainly wondering about. My eye catches the yellow and nearby gray fittings that are bare.

 

The yellow and gray fittings are bare, yes, but they're not going to cause any hissing sounds. You're missing a bunch of vacuum lines, but they likely went with the rest of the smog equipment when it was removed.

I can't really tell from your picture, but is one of the vacuum connections on your carb unused and not capped? There are three barbs on the front of your carb...one connected ignition advance, one to PCV, and the 3rd one (driver's side) looks like it is unused? Is it open?

I'm no expert...just looking over your pictures.

 

You have a non-stock carb on there. You will not have places to hook all the vacuum lines up. Pretend your engine was from the 60's with the bare minimum of vacuum lines. If you have underhood inspections and have to pass smog, you may have a problem.

 

Good old Clark Count Washington doesn't require emissions on vehicles 25 years and older.

I was leaning towards the aftermarket carb handling whatever needed vacuum lines all on it's own. I will check to make sure any are capped that look to be open.

The yellow and gray ports, they look like temperature controlled valves being ported off the coolant neck, that right? I could cap them just for brevity but don't think they are actually sucking air.

 

If you ever drain the coolant for some reason, take them out and put plugs in their place

 

I do need to drain fluids since I never did since I bought it. I would only drive it on the weekends here and there but recently did daily it on the highway for a week while my other car was getting new coils and VVT solenoid. During that week of daily driving, I knew I need to get in under the hood and so some basic maintenance.

New engine build is in the works and hopefully by end of the year Dan will get a new motor and transmission. So just enough to keep him running till then.

 

As Franklin said 60's vacuum hose routing - Dist. vacuum advance to carb, Power brakes to manifold, and if you have AC, vacuum for that is all I can think of.
That is all I have hooked up on my 81 F100, oh and the charcoal canisters to vent the fuel tank & carb bowl vapors.

The yellow & gray temp controlled valves don't need to be capped as you don't have any vacuum supply to them.
As someone pointed out if you don't like the looks of them sticking out like that when you have the cooling system drained pull them and install a threaded pipe plug.
Dave ----

 

Cool. That makes sense. I'll get in there and make sure the advance, brake booster, and canisters are hooked up. Have AC but no compressor (will want to get that sorted at some point).

 

You will still need the AC vacuum hooked up as it is needed to work the vent doors for floor, defrost, dash vents even with out the compressor.
You also don't need to hook up the canisters at this time and would not till you et it running good then go back and hook it up.
My canisters are not hooked up to use a valve as per the radiator sticker. I went right to the top of the PCV port by passing the valve.
Dave ----

 

Ahh I see. Thinking about it, not sure what vacuum would control on the compressor haha.

In all honesty, the truck performs as I would expect. Don't feel like it's lacking power at all. My parent's neighbor has a dyno and I am tempted to roll up and have them do some pulls.

 

I was just out poking my head around and there what you spotted is capped. It's white and just dirty. However, I do have one port that is not hooked up.




That diaphragm at the end of the riser / spacer thing.

 

That thing at the bottom of the picture. Does it have a little lever coming out near the hood hinge that you can move back and forth? If so, that is your inside air/outside air damper actuator. When you put the A/C controls on "max", vacuum gets put on this actuator and it recirculates inside air instead of pulling in outside air with the fan.

 

This shot here is back of the engine. I did see the actuator you are talking about and is hooked up and working.

From my inspection, everything looks taken care of minus that diaphragm thing. From what I can find on diagrams, it's an anti-stall dashpot?

 

Ohhh. EGR valve. Should that be hooked up or capped?

 

Sounds like a vacuum leak in the power brake booster. Squeeze the rubber vacuum hose attached to the booster [use needle nose pliers] and if the hissing sound stops, then you will know the source.