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tucsonjwt · 05-01-2015, 10:21 AM

As I recall, trucks over 8600 GVWR were considered heavy trucks and did not require cats in the early years. I don't know if your half was heavy enough to qualify. My 83 C20 has no cats and no vapor recovery system, but it has a smog pump and a lot of smog lines - the pump and lines get a lot of inspection every time I go through emissions in AZ. All of that junk does take a toll on fuel economy, especially with a 454, but after a recent cheap rebuilt carb the emissions are very low.

05-01-2015, 10:21 AM	#1
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,198	Re: Oregon DEQ test results :smoke: As I recall, trucks over 8600 GVWR were considered heavy trucks and did not require cats in the early years. I don't know if your half was heavy enough to qualify. My 83 C20 has no cats and no vapor recovery system, but it has a smog pump and a lot of smog lines - the pump and lines get a lot of inspection every time I go through emissions in AZ. All of that junk does take a toll on fuel economy, especially with a 454, but after a recent cheap rebuilt carb the emissions are very low.