This has been beat to death, I have been looking in the two manuals I have for this 1980 F150, with 302...

Vacuum diagrams are like pictures worth a thousand words... or questions.

I found a lot of vaccum sources/tubes not hooked up at all and I am suprised the truck would even run, much less be getting 12-13 miles to the gallon.

I am trying to identify certain parts of the system and I am not having much luck. I don't know what all was considered stock on my truck but here goes.

The question is, is this a EGR/PVS valve on the back on the intake manifold or a vacuum source?
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what should be here? (in the rusty thread hole)



and what is this called? (blue vacuum valve in the middle)


probably more questions to come...

 

I guess the real question is, do I need a PVS, or can I just route the distributor vacuum straight from the carb?

 

Yes, you can run the dist vacuum directly to the carb. Hook it to the port that does not have vacuum at idle, but has vacuum as you rev the engine.

 

Your only getting 12-13 mpg,my 302/4 sp od,I get 18 mpg.the only vac lines I have on mine are vac advance straight to ported vacuum on the carb,pcv and power brakes,and one for the heat riser to the air cleaner.

 

so the pcv, and aircleaner heat riser get straight manifold vacuum, or off of the carb ported?

 

pvc,power brakes and heat riser go off manifold vacuum and dist off of ported vacuum. if you had and auto tranny you would also have one line going to modulator valve.

 

you wouldn't by chance know what vaccum source is used for the EGR valve?

 

i believe it also would be ported vacuume as well,you don't want it on during idleing or when you floor it.it should only open during crusing.

 

The egr also goes through a vacuum switch screwed into the water jacket. They don't want the egr working till the engine is somewhat warmed up(coolant about 100 degrees)

 

i was hoping you would chime in Franklin2.you have more knowledge in this than me.

 

Thanks to the both of you. I really appreciate the help. I am not the best at reading vacuum diagrams. Electronic circuits are more my thing... similar, but acronyms are way different.

 

Plugged her all together. I stared at the diagram on the radiator housing for a while and it started to make sense. The #1 photo above is a ported vacuum switch, which is on the opposite end of the intake manifold from where I've seen others (usually in the water pump outlet housing from what Iv'e seen online) The bottom is the ported vacuum inlet, the top is the switched output that is supposed to go to the EGR and air pump bypass stuff, which makes the EGR get ported vacuum only when the engine is warm enough.

the ported vacuum is tee'd to go to the ported vacuum switch as well as the distributor and the unidentified blue thing in pic #3 which is between the carb and charcoal canister, another vacuum line goes off of this to the PCV.

I have full manifold vac going to the power brake booster and to the air cleaner bi-metallic valve which then goes to the snout to let warm exhaust manifold air go into the carb when cold.

She starts up fine and the choke operates well, she idles a little high now after warming up though. No hesitation anymore, although she seems like she is missing.

Next up is spark plugs and wires (which I think are burning on the exhaust manifolds....) as well as a compression test.

Thanks again guys!

 

(wife is mad now she doesn't understand why, even though the truck saves us more money than it costs. Go figure.)