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L18 swapped 620, need to legally smog. What all do I need?


NoMoneyZ

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Many years ago, this truck was equipped with a l20. When it went south it was swapped with a l18. A few years ago we had it rebuilt so my mom could use it as her work truck. It runs great but there is no smog stuff on the engine and I have lost all connections with "smogs".

 

Does anyone know what all I need to put the smog equipment back on? I'm not sure what this engine came with. I know it will take some digging, but once I have everything it will make it much less of a headache when registration is due. So far the truck has an old cat that probably needs replacing.

 

 

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What year is the truck

Auto or manual?

Was it originally CAL, CAN or FED emissions? It will say on the under hood emissions sticker.

 

Get the Factory Service Manual for the specific year. It has lists and diagrams for the six different emission configurations that year.

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In CA?  L18 would never be legal, as it's technically an "older" engine.  Of course, no one may notice that, but the missing smog equipment is gonna be a problem.  You'll need original, unmolested manifolds.  It's a '77, right?  So you'll need a '77 manifold set, which contains the EGR connecting the 2..  '76 will work too, it's close enough you can't tell the difference.  If unmolested it will have the air injection tubing in place.  That then requires the air pump and all associated plumbing, the air pump's air filter, a stock air cleaner, the anti-backfire valve, and a stock 1977 Carb specific to what particular configuration it is.

 

The vacuum routing will be an issue unless you have a factory manual, AND manage to find a '77 in the junkyard with everything in place to remove (and mark where it goes) beforehand.  It's a spaghetti of hoses (though not nearly as bad as domestic V8s of the same era).

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What year is the truck

Auto or manual?

Was it originally CAL, CAN or FED emissions? It will say on the under hood emissions sticker.

 

Get the Factory Service Manual for the specific year. It has lists and diagrams for the six different emission configurations that year.

Truck is a 77 620. 4speed manual. California truck. I'll see if I can find one on ebay.

 

In CA?  L18 would never be legal, as it's technically an "older" engine.  Of course, no one may notice that, but the missing smog equipment is gonna be a problem.  You'll need original, unmolested manifolds.  It's a '77, right?  So you'll need a '77 manifold set, which contains the EGR connecting the 2..  '76 will work too, it's close enough you can't tell the difference.  If unmolested it will have the air injection tubing in place.  That then requires the air pump and all associated plumbing, the air pump's air filter, a stock air cleaner, the anti-backfire valve, and a stock 1977 Carb specific to what particular configuration it is.

 

The vacuum routing will be an issue unless you have a factory manual, AND manage to find a '77 in the junkyard with everything in place to remove (and mark where it goes) beforehand.  It's a spaghetti of hoses (though not nearly as bad as domestic V8s of the same era).

I figured no body would be able to tell visually that it wasn't the correct engine, I just need to put whatever came on it back on and replace the cat. Thanks both for the input. I'll get searching for a service manual and go from there.

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California smogs everything 1976 and newer, so 510s are too old but most 620s are not.  That's why 73-75s are desired. 

 

Could be worse- Nevada smogs everything 1968 and newer.  Technically, federal law states that everything 1968 and newer cannot have altered emissions components but it's up to the individual States to enforce.

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