Help with 1/2 way done Desmog!!

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Oct 1, 2006
Just purchased a project that was 1/2 completed. Previous owner attempted a desmog and got 1/2 way through it. Not sure where to begin. Does anyone have a diagram/schematic/map of a desmog? This is a 2F, don't know where to start since i am just inheriting someone else's work. (I did get a really good deal though ;p)


Give us a hand here, what year truck? What has been removed? Do you have to pass emissions in your area?

Congrats on the new rig and start a build up thread!
The truck is a 78', i do not need to pass emissions in my area. The air rail has been taken off and plugged with bolts. It appears all emissions stuff has been removed.
Here's a pic of how it should be set up.

Could a moderator please add a link to this pic off the tech page as a "1978 Federal 2F desmog schematic"?
Not to hi-jack... but first thanks to Jim for posting that daigram! I needed that for my own '78 de-smog.

One question though, on the carb where the line from the power valve heads down to the charcoal canister, there is a smaller vacuum line attached to what looks like the same port. Does this need to be plugged (I'm assuming that's the answer, so the vacuum will reach the power valve and close it) or open?

I'm still curious about the power valve - I think from other posts that it needs to be plumbed to manifold vacuum. Is that correct?

Also, are most people hooking up the lines to the distributor cap? Does anything special need to be done there?

There is no power valve connection on most 1978 2F carbs, including the schematic above.

The hose going near the PV is just the large bowl breather hose that dumps to canister.

Dissy cap ventilation system is stand-alone, not emissions related. Leave as-is.
Thanks for posting that Jim, I think I have all the parts-not sure about blue VTV and no EGR on mine.
Try and down load a FSM manual from the internet. Cant remember were I got mine, maybe from here. And then go to MY DESMOG THREAD in the 60 section. Tons of info there. I think you will be able to figure everything out using both of those resources.

But the key is keep studying. Oh and one more thing, watch all of fj40jim (Jim C) post. He is the desmog guru.

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