1977 K20 Heavy Duty Emissions

Evening All,

My name is Johnny. I live in Alpine, Ca., just a little outside San Diego.

I picked up a K20, 4x4, automatic transmission, no rust and decent interior. The exterior is sun baked, but not too bad. The truck is a one owner prior to me and he passed away about a year back. His friend sold it to me. It was last on the road in 2002.

It runs and I'm going through it now to get it road worthy. Under the hood the only sticker left on it is the jack instructions, and the Federal emissions stickers are gone. I assume they were on the air cleaner cover.

If anyone could help me out with figuring out what the emission sticker / decal looks like, I'd appreciate it. According to a VIN lookup it's a Federal emissions truck and a heavy duty (GVWR 8400). Seeing as I'm stuck behind enemy lines, I am just thankful it doesn't have the cat and the extra burden to get it passed through the smog folks out here.

- JB

Hey Johnny. Congratulations on the K20. I got my '76 K20 about 3 years ago and have been going through restoration. I'm in the same boat with the smog. My truck didn't have any of the original equipment, so I slowly reconstructed it. It actually wasn't too bad. Here is what I learned for the '76 with HD emissions. I assume it is the same for '77, but you'll want to confirm.
* No catalytic converters required
* No EGR
* Yes on a smog pump, which means you'll need the manifolds with the air inlets, or the CARB approved headers by Edelbrock. I went with the Edelbrock ceramic coated smog legal headers. They are really nice.
* You need the thermostatic vacuum switch on the water neck. This controls vacuum to the vacuum advance, depending on water temp.
* Supposed to have the idle kicker solenoid (I don't recall the name of hand). It is a vacuum controlled solenoid that kicks the throttle slightly open under high vacuum situations. These are unobtanium. I've looked for years. You may get lucky. I have a work-around design that uses an electric solenoid, driven by a vacuum swtich. I'm not sure the smog guy will really care about that item, though. We'll see.
* Have to run the stock air cleaner with all the features hooked up. Can't recall their exact names. One is a vacuum valve and the other is the hot air valve.
* You can get a correct carb, built to the original specs (or slightly modified depending on how you plan to build your engine) from a number of Q-Jet specialists. I got mine from National Carburetor and I'm very happy with it.

The smog pump was probably the hardest item to find that was correct. Will take some searching.

I've looked and looked and haven't found the correct air cleaner smog sticker. There are a lot available, just not for the engine/year/emission level of mine. My truck has the 400 engine.

So far, I've gone through everything from the ground-up. The only thing left is to get it painted (body work is done) and install my USA1 interior (that took ~2 years to finally receive). Happy to answer any questions you have.

-Rob

Hey Rob, nice to meet you and thanks for taking the time to write me back.

That’s interesting about the smog pump. I am hoping to avoid having to put one on. Mine came out of the Fremont plant and the intel I have seen, which I admit is tainted a bit by hopeful and wishful thinking, seems to indicate my truck was a Federal emissions truck and they didn’t push out smog pumps for these 350’s in ‘77.

It isn’t the end of the world if I have to do it but would be nice. Thanks for the tip on the Edelbrocks. That’s good info on everything.

I’m intrigued about the workaround design you mentioned. I’m in the middle of discovery learning as much as I can and may need to send a bottle of scotch or your pleasure your way and beg for a description of how that workaround works.

My sincere thanks again.

I’m keeping some notes on my progress of the build here on the forums and over at YouTube if you’re interested.

Respectfully,
Johnny