Maybe about as much as your newer (obd2 vehicles) at startup.
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Thinking of adding catalytic converters
- Thread starter CraigFulton
- Start date
Maybe about as much as your newer (obd2 vehicles) at startup.
Damn that's putty. My truck was that color.
I had the exact same problem with my '86 K5. At the time it had a 305 with a Holley and NO catalytic converters. All my life I've been anti-cat. But, I spent the better part of a year trying to lean out the mixture and such just so I didn't have all the exhaust fumes. I finally gave up and put a pair of quality Walker brand catalytic converters on the truck. Boom!! I had no more exhaust fumes! Now I can drive with the top off and not smuff-a-cate (made up word). Keep in mind the cats really need to be as close to the exhaust manifold as possible and at normal operating temp to burn off the gas fumes, but they do the job well. I have not noticed any mileage loss. But I wouldn't care either way as long as I don't have any more fumes. I swear by cats... use them!
Don't be tempted to "cheap-out" and buy the bargain cats - they will melt down on you and burn a valve or two. Get quality cats!!
This is the exact kind of reply I was hoping to see.
T
tenderfoot
Guest
Alright, I live in Austin. Just got rid of my cats. No difference before or after. I used to live in Carson City, NV. They had no emissions at all. So I ran all new exhaust from hooker headers back to flowmasters. Had an Edelbrock intake Edelbrock 650 on a 350 with a cam. Thing ran like a timex with no smell. I have the same set up now only a bit smaller cam, headman headers, magnaflows. Stinks all to high heaven. Doesn't run to it's potential, bogs under sustained high rpms. There is quite an elevation difference but I'm not giving that much thought, yet.
My point is it's not cats. It my inability to figure out my tuning deficiency. I will get her figured out and will be smarter in the end for it. Get cats if you want. It's my opinion that if it even works it's just masking the real issue.
My point is it's not cats. It my inability to figure out my tuning deficiency. I will get her figured out and will be smarter in the end for it. Get cats if you want. It's my opinion that if it even works it's just masking the real issue.
My '90 Jimmy smells better out of the tailpipe now with the new '72 engine and Edelbrock injection than the old TBI engine did. It didn't have and still doesn't have a cat. Granted, it still has some smell to it when cold, but nothing very obnoxious. And my 2 carbureted trucks in the garage don't make excessive smell when I start them, only if I let them run inside too long.
So my point is that I believe some of the problem is the fuel mixture. If you get that right, then put a good cat on. But there will still be some smell when cold. The company truck shows that to me. It's am old '07 GMC with a 6.0 and all factory exhaust. I park it inside every night.
So my point is that I believe some of the problem is the fuel mixture. If you get that right, then put a good cat on. But there will still be some smell when cold. The company truck shows that to me. It's am old '07 GMC with a 6.0 and all factory exhaust. I park it inside every night.
CraigFulton
1/2 ton status
Thanks everyone. I’m getting into this thing tomorrow. I’m going to replace the exhaust manifold gaskets to ensure no exhaust leak. Then I’m going to pull and look at the plugs to see what story they tell me. Lastly, I’ll start analyzing the settings on the Holley sniper and see what’s going on. I just think it shouldn’t be eye burning after an hour of driving when I back into the garage. And I am getting 7mpg. Something is up.
Sounds Rich, I get 9-10 with 4.56 gears, 35s and no OD.
CraigFulton
1/2 ton status
Definitely an exhaust leak on this side that doesn’t have the O2 sensor. The a-hole I bought this “turn key” rebuilt Blazer from broke the exhaust bolt off in the head. I hoped a pair of vice grips would get it out but it wouldn’t so I pulled the head and drilled it. This sucks.
But pulling the plugs they look really good.
But pulling the plugs they look really good.
CraigFulton
1/2 ton status
F yes it did! The guy I bought this from was a hack. Had the engine rebuilt but the assemble of the accessories was piss poor. Everytningnis loose or broke.
CraigFulton
1/2 ton status
Gives me a chance to repaint everything in the engine bay...AGAIN. I got white overspray on everything when I was painting the two tone. Paint cloud came up from underneath and covered everything on this fresh engine. This thing has been a pain in the ass.
Ahh, welcome to truckdom
it might be a pain in the ass, but it is gorgeous! 
I liked this because of your hard work! Don’t quit!
T
tenderfoot
Guest
I woke up with a thought instead of a song stuck in my head.
Could a bad PCV valve cause a stink.
See what I did there.
Soon as I get some time I'm gonna go get a new PCV and brake booster check. And maybe look a little closer at a possible leak at the booster and hoses. You have fuel injection so the PCV valve would be different but, I wonder
Could a bad PCV valve cause a stink.
See what I did there.
Soon as I get some time I'm gonna go get a new PCV and brake booster check. And maybe look a little closer at a possible leak at the booster and hoses. You have fuel injection so the PCV valve would be different but, I wonder
Some people are jack-holes... Don't let it dissuade you from enjoying the truck. You're just getting to know her better.
Looks like you found the source of most of the smell.
