So This is the problem. I have a 78 Chevy Blazer full size that wasn't built with Catalytic coverters, however the garages in my area are doing nothing but arguing with me telling me that it was built with them. I don't know if there's a particular way that i can tell that they were built with them or not. It doesn't have a restrictor plate in the gas filler tube. The truck I believe was built for commercial use and that's why I think that it wasn't built with them but I have no way to prove it. I was told that you could possibly tell by the VIN number but I'm not sure how I would go about doing that? If anyone can help me with this issue it would be appreciated being that I must get this truck back on the road and inspected ASAP!

 

Try calling your local dealer with the vin? Maybe RPO code?

 

I'm not entirely sure how you could tell but when I took in my '78 k5 to have it smogged the guy at the shop had a little book in which he looked up my truck and it told him it didn't need a catalytic converter OR an EGR valve.

 

This from the EPA:
"Catalytic converters have been installed on most 1975 and newer passenger cars and light-duty trucks by the manufacturers to reduce exhaust emissions and allow the vehicles to meet Federal standards."
Yours should have come with on on it. At some time an owner may have removed it thinking it would never matter.

 

What size engine did your's have in it? I'm getting the whole "well it was optional that year" run around. It originally had a 305 and was swapped out for a 350. I'm getting mixed answers from most of the auto parts places and exhaust specialists in the area and it's getting extremely overwhelming.

 

I am pretty sure that all Blazers came with cats starting in 1976 (except diesels). I am also pretty sure that federal emissions law exempts vehicles built before 1982 or 83 (???). That could just be a Texas thing so don't quote me on that... You need to talk to someone who knows Pennsylvania emission laws.
On a side note... You could just go down to your local muffler shop and have them install a hollowed out cat (or two). It is perfectly legal for them to do so, they just can't permanently remove one.

 

[quote=bandidolenny;215636]I am pretty sure that all Blazers came with cats starting in 1976 (except diesels). 1.I am also pretty sure that federal emissions law exempts vehicles built before 1982 or 83 (???). That could just be a Texas thing so don't quote me on that... You need to talk to someone who knows Pennsylvania emission laws.
On a side note... 2.You could just go down to your local muffler shop and have them install a hollowed out cat (or two). It is perfectly legal for them to do so, they just can't permanently remove one.[/quote]

1. I have no idea where you came up with that. Been here in Texas all my life and never heard of such a thing. Check with the Texas DOT on that one.
2. It is most definitely a Federal violation for any shop to remove or make inoperable a catalytic converter on any vehicle driven on public roads in the USA.

 

My blazer came stock with a 350 so maybe the bigger engine ones didn't require a cat?

 

The early emissions laws were based on the GVWR of the vehicle in question. If it came with a catalytic converter, federal law requires that it has one.

Catalytic converters became standard on the K5 Blazer in 1975, but only on the models with a GVWR under 6000lbs up until 1979. In 1979, the GVWR was raised well in excess of that (8500lbs IIRC) causing all 1/2 ton and most 3/4 ton vehicles to be required to have catalytic converters.

 

A friend recently had a 1984 one ton truck inspected and was told by two different shops that since it was newer than 82 it was required to have a cat. That's how I came up with that... but like I said, don't hold me to anything here.