Latest Surprise
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Joined: Jul 2016
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Latest Surprise
My new to me 78 with the L48 is missing some of the emissions components. There is no air pump, oxygen sensor or catalytic converters. The rest is there from what I can tell.
Problem is strong exhaust fumes idling at a light, in garage etc. Knew there was a fume issue when I purchased but there was gas leak at carb which confused the issue. Had carb rebuilt, plugs, wires and a few other non engine related items repaired.
Still have the fume problem and after searching here with others having the same condition it appears that not having the catalytic converters is causing the problem. Pre emission cars did not have this problem so what is the difference the way the engines are setup?
Can just installing the cats solve the problem without having to completely restore the emission system?
Problem is strong exhaust fumes idling at a light, in garage etc. Knew there was a fume issue when I purchased but there was gas leak at carb which confused the issue. Had carb rebuilt, plugs, wires and a few other non engine related items repaired.
Still have the fume problem and after searching here with others having the same condition it appears that not having the catalytic converters is causing the problem. Pre emission cars did not have this problem so what is the difference the way the engines are setup?
Can just installing the cats solve the problem without having to completely restore the emission system?
Instructor
Joined: Jun 2015
Posts: 169
Likes: 10
Is the motor stock? Or has it been rebuilt for performance with a big cam etc?
My new to me 78 with the L48 is missing some of the emissions components. There is no air pump, oxygen sensor or catalytic converters. The rest is there from what I can tell.
Problem is strong exhaust fumes idling at a light, in garage etc. Knew there was a fume issue when I purchased but there was gas leak at carb which confused the issue. Had carb rebuilt, plugs, wires and a few other non engine related items repaired.
Still have the fume problem and after searching here with others having the same condition it appears that not having the catalytic converters is causing the problem. Pre emission cars did not have this problem so what is the difference the way the engines are setup?
Can just installing the cats solve the problem without having to completely restore the emission system?
Problem is strong exhaust fumes idling at a light, in garage etc. Knew there was a fume issue when I purchased but there was gas leak at carb which confused the issue. Had carb rebuilt, plugs, wires and a few other non engine related items repaired.
Still have the fume problem and after searching here with others having the same condition it appears that not having the catalytic converters is causing the problem. Pre emission cars did not have this problem so what is the difference the way the engines are setup?
Can just installing the cats solve the problem without having to completely restore the emission system?
Team Owner
Joined: Jun 2000
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From: Southbound
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Joined: Jul 2016
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Believe the engine is stock and the fumes are definitely exhaust. No pressure when gas cap is removed. Didn't mean pre emission c3,s just cars in general.
A search about strong exhaust fumes point to the missing catalytic converters as being the problem. My question is will installing converters solve the excess fume problem or can the engine/carb/timing be setup different (like a pre emission type engine) take care of it?
A search about strong exhaust fumes point to the missing catalytic converters as being the problem. My question is will installing converters solve the excess fume problem or can the engine/carb/timing be setup different (like a pre emission type engine) take care of it?
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Pro
Joined: Jan 2016
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From: Reno Nevada
Believe the engine is stock and the fumes are definitely exhaust. No pressure when gas cap is removed. Didn't mean pre emission c3,s just cars in general.
A search about strong exhaust fumes point to the missing catalytic converters as being the problem. My question is will installing converters solve the excess fume problem or can the engine/carb/timing be setup different (like a pre emission type engine) take care of it?
A search about strong exhaust fumes point to the missing catalytic converters as being the problem. My question is will installing converters solve the excess fume problem or can the engine/carb/timing be setup different (like a pre emission type engine) take care of it?
installing a Cat will have no effect on your smell other than potentially turning it into a rotten egg smell if you are running rich.
You need to determine what the smell is. Is it running rich? Is it a raw fuel smell? what are you smelling. the smell of exhaust does not help much as it should smell like exhaust. What smell are you smelling that makes you think something is wrong?
Pro
Joined: Jan 2016
Posts: 502
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From: Reno Nevada
If it smell like gas at the exhaust and you are getting excess black soot, then your carb is not set up correctly. You need to rejet your carb or at least adjust it.
Adding a cat will only plug the cat up and ruin it.
What carb are you running?
Last edited by 73racevette; Sep 6, 2016 at 06:12 PM.
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
I'll repeat the first advice you received to check ALL of the hoses involved in the EVAP (fuel vapor) system! If the hoses are toast (like mine were) fuel vapors wind up in strange places due to the connection with the PCV system.
Pro
Joined: Jan 2016
Posts: 502
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From: Reno Nevada
Possibly, but black soot in the tail pipe is definitely rich. Check your plugs to see how rich you are running. Sounds like a carb to me. Would not hurt to check other lines, but fixing the soot issue is going to involve the carb.
Drifting
Joined: Apr 2011
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From: Deerfield Illinois
2022 C3 of the Year Finalist - Modified
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These old cars smell this way. When I start my Vette in the garage I let it warm for a second and I pull it out right away. I also do the same when coming home. I leave it in the driveway for a half hour with the hood up to cool it down. The house will smell like horsepower if I don't.
Black soot on the exhaust could be multiple problems. Check carb settings and adjust, check timing, tuning. Pull plugs inspect and clean or replace them. Also, I run the best gas and highest octane I can find, 93 by me. I feel your way too rich right now.
Black soot on the exhaust could be multiple problems. Check carb settings and adjust, check timing, tuning. Pull plugs inspect and clean or replace them. Also, I run the best gas and highest octane I can find, 93 by me. I feel your way too rich right now.