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1977 Need Emission Guidance

ZombieK5

ZombieK5

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I am back on the forum for the first time since selling my 85' K5 back in 2004. I just purchased a 1977 K5 that apparently had a 400ci as original equipment.

I am having issues finding data regarding the "original" condition of the truck and the local emissions shops are killing me with their "knowledge" or lack of it.

The truck is of course modified with lifts (4" suspension + 2" body), overgrown tires, better axles (14Bolt and Dana 60) and a 468ci BB Chevy under the hood hooked to a 700R4 and a cast iron NP205. 20" Weld Racing Rims (which I need to get rid of).

I need a verifiable source of info regarding the existence of cats and/or smog equipment when it was new. I have read over the existing posts but there was not any consistent conclusions about what was really going on with the K5's in 1977.

My VIN# starts with CKR187F######

The vehicle is currently in NYC but I am driving it back to Philly next week. I also have issues with the bumper height which is 36". PA laws require it to be lower (29" max)....that also means I need to determine the official GVWR which dictates the max height. So much to do.

ALSO need to re-install the EBreak lines from cab to 14Bolt drums.

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I would ask the DMV what your requirements are. Isn't anything older than 40 exempt everywhere but CA?
Since it never came w a BBC, Iwould think you would fail on visual alone.
Cats started in 75 for anything less than 6000gvw, and in 79 all trucks less than 8600gvw.
 
Hmmmm, from my research in the past 15 minutes it seems the '77 K5's were about 6,100 gvw.

Chevy mechanic said I would only have a visual inspection so the simple presence of a Cat, vapor canister and maybe EGR will get me by but I'd like to be sure. Our DMV is useless. They don't have specific vehicle info and told me i needed to have a Cat. I dont believe that.
 
All 77 blazers left the factory with a CAT. Federal law says you have to have a CAT. No Blazer left the factory with a fat block.
 
frankin5 said:
All 77 blazers left the factory with a CAT.
Click to expand...

Sorry but I have to disagree, my 77 has the factory RPO sheet in the glove box and it shows factory dual exhaust. I believe there is no way the factory put dual cats on anything in 1977 except maybe Corvettes. Also there are only heat shields where the mufflers are located, if it had cats there would be another set of heat shields.
 
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Capt Ron said:
Sorry but I have to disagree, my 77 has the factory RPO sheet in the glove box and it shows factory dual exhaust. I believe there is no way the factory put dual cats on anything in 1977 except maybe Corvettes. Also there are only heat shields were the mufflers are located, if it had cats there would be another set of heat shields.
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That's a K5? What engine?
I suspect the 400's did get away with fewer emissions.
 

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Just found the actual 1977 Blazer Brochure. Very nice to look at and good info but again, no emission data.

However the brochure shows the BOTTOM of the Blazer with the body removed. There are NO CATS. Unless anyone can tell me they are hidden, I dont see them

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I went ahead and ordered all the Chilton/Hayes manuals and the OEM Factory manual. HOPE they have the answers.

Service Manual.jpg
 
The LMC catalog shows catalytic converters for 78 - 79 with 400 . not 77. This is not a verifiable source but it's safe to say that a 77 with 400 motor probably did not come with cats.

smog shop should tell you what you need. Don't use a smog shop in the city, go to rural area where everyone has old Chevy trucks
 
Can you see the link in my signature block? I'd check the parts manual.

It's going to be a mess because of the number of exhaust systems in use at that time, but it's worth a shot. You probably need to know the RPO to be 100% certain, but if you know the original engine, you'll be able to at least narrow down what was possible.
 
dyeager535 said:
Can you see the link in my signature block? I'd check the parts manual.

It's going to be a mess because of the number of exhaust systems in use at that time, but it's worth a shot. You probably need to know the RPO to be 100% certain, but if you know the original engine, you'll be able to at least narrow down what was possible.
Click to expand...


I do not see a signature or a link

Screenshot_20200223-015337_Chrome.jpg
 
dyeager535 said:
Can you see the link in my signature block? I'd check the parts manual.

It's going to be a mess because of the number of exhaust systems in use at that time, but it's worth a shot. You probably need to know the RPO to be 100% certain, but if you know the original engine, you'll be able to at least narrow down what was possible.
Click to expand...


I couldn't find a signature link. Also, the original engine from this truck is long gone. It has a 468 BBC in it right now. I am sure the RPO is long gone also. I have a stack of paperwork from the seller but he is about to 15 person in line to buy this truck.

I went I went to a Chevy dealer but they no longer have their paper books from the 70s and early 80s. Somebody threw them out several years ago. I will try another Chevy dealer if I can figure out which one is Ben in the area send 1977. I'm also going to hold out until the factory manual gets to me. Hopefully it specifically details the emissions diagrams from that time period.
 
http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1

I suspect the issue is on phones. I can't see my signature on the phone either. PC it works fine.

Anyway, pretty sure the GM heritage center can't pull up RPO tags by VIN. I believe that was discussed in here. But the VIN itself should specify the engine IIRC, and I want to say the GM VIN code breakdown is in the front of one of the two parts books (there are two for each year, the illustration one is easiest to start with). You can find various GM VIN decoders online as well.
 
The oem manual has good schematics
Heres pic of my 78

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Seems like cat or no cat is determined by emmision rpo

Light duty says all were equipped, heavy duty not mandatory but still depends on rpo, fed tier o, fed tier1 , ca spec , ect.
 
dyeager535 said:
http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1

I suspect the issue is on phones. I can't see my signature on the phone either. PC it works fine.

Anyway, pretty sure the GM heritage center can't pull up RPO tags by VIN. I believe that was discussed in here. But the VIN itself should specify the engine IIRC, and I want to say the GM VIN code breakdown is in the front of one of the two parts books (there are two for each year, the illustration one is easiest to start with). You can find various GM VIN decoders online as well.
Click to expand...
If you flip the phone sideways you can see the signature
 
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