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Need help with exhaust!

B

bwoodard

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I have put a new crate motor in my project blazer and I need to figure out a new exhaust system because the passenger exhaust manifold is cracked and the y pipe was made to fit that manifold and the exhaust diaphram. I want to put headers on buti do not want to buy two of everything and if I can do it all myself that would be great. I have looked at Thorley headers that merge into a y pipe has any one used these and or has any other ideas that would be great and could send pics.
Those dam CATs are expencive and I have to take it to emissions when all is done. Thanks to anyone that can help.
 
When I ran my headers and duals I used a single cat on either side, like $80 a piece, and I think those are the cheap ones (catco). The cats made my exhaust stink real bad, you know that nasty sulfer smell? our emissions testing was stopped so I took them off, I just couldnt stand the smell. Make sure you get good quality ones if you do.
 
I have a feeling something else is going on here, besides cheap converters. I have a friend with a Monte Carlo with a "quality" cat converter, except larger diameter pipes, and headers. His car smells TERRIBLE, like you describe.

I'm thinking either this is a problem of mixture reaching the converter (friend dumped the CCC system in favor of old school stuff) and also dumped the converter AIR injection. Trucks didn't get AIR injection AFAIK, so thats probably not the problem.

One of the reasons converters are not allowed to be ADDED to vehicles is because they must reach the proper temp to work correctly. Without accurate temperature testing, a backyard mechanic isn't going to get the converter in exactly the right spot to heat up to that temp, and besides, when going with duals, you are cutting the amount of exhaust, and heat, that the converter is seeing.

I don't know exactly how you'd cure the problem, but would be interesting to have someone fab up sections of pipe, to see if the distance/volume of exhaust from the engine really is the problem. I bet it is.
 
Dave, How long did you run the cats?? Just curious because I have cheap cats and a new exhaust system, and it smelled weird for about a week then nothing.
 
I thought if your vehicle came with single cat you had to stay single.. your couldnt go true dual. I live in Colorado and run single 3" for that reason, am I right or can I go to true dual 2.5"? Also went to an air injected cat on my 84 because I dont have air injection into my exhaust manifolds now "headers"
 
Yes, you are correct. It is illegal to change the amount of converters the vehicle originally had, + or - Only exception is if going to a newer drivetrain (for example engine, transmission, exhaust) from a newer Camaro with dual cats, THEN you can have duals, but you have to have ALL of the emissions stuff in place.

A lot of people run true duals with no cats (myself included) because I'm not tested, and its what I had laying around. If there is no visual inspection, as long as you don't move, you won't get in trouble as long as you can pass the sniffer, if you even have THAT test. Emissions laws/areas change, so thats something to always think about before ripping something off...you may have to put it back on later.
 
I ran the cats for about a year. I had them installed at a custom exhaust shop along with the rest of my exhaust. They made sure they were far enough from the headers so they wouldnt get burned out (thats what they said). I am running 2 1/4" pipe on both sides all the way back with turbo mufflers. I have a new 350 crate motor w/o the air pump, egr valve, and the rest of the emissions stuff. I had the carb tuned at a shop that works on dirt oval race cars. I think it might still be a bit rich, but it's how they set it. I kind of get a bit of blue/white smoke for a few seconds after starting.
I have an Edelbrok 600 cfm carb on the performer alunminum manifold. Any suggestions on tuning it better? Also I got an HEI distributor made to work on non computer controlled vehicles (not really a computer, but the mixture control settings that used to go to the quadrajet)
 
I'd get the A/F mix right first, and make sure your engine temp is 195 (t-stat) but other than that, I think you'd have to have an accurate measure of the cat converter temp, and thats going to be hard to do. I'm not sure of the +/- temperature that cats are effective at, but for some reason 600 degrees comes to mind.

Again, more than likely, its why you can't ADD converters...they are specifically designed and installed by the auto manufacturer to work at a specific temperature, and only someone that will invest a fair amount of time and money would be able to retrofit cat converters, and have them be as effective as something factory installed.
 
i had 3 inch duals all the way back. no cats just tripple chamber cheap mufflers. it sounded great at an idle and roared down the HW. sounded like a HD
Grant
 
Mine came through with single- but when the previous owner wanted to upgrade the exhaust he wanted duals- cats, and all- with 3" pipes. It took him 4 different exhaust places- before he found one that would do the work. Once they are on- the only problem is WHERE you get the inspection done.

In my case, not only is my truck "illegal" with the duals exhaust, it also does not have mud flaps- which any truck lifted above stock height is required to have here. to top it off my bumpers are almost a full inch higher than legal as well.

When he got it inspected every year...its normally $15 in this state.. he ended up having to pay $20.00. I know the guy that he went to, and have already discussed with him getting it inspected this spring. for $5 I'm not going to spend the time for $$ to fix the stuff- or take off my exhaust.

whats that old saying It's not who you know its ....oh never mind!! :O

Brandy
 
Mine came through with single- but when the previous owner wanted to upgrade the exhaust he wanted duals- cats, and all- with 3" pipes. It took him 4 different exhaust places- before he found one that would do the work. Once they are on- the only problem is WHERE you get the inspection done.

In my case, not only is my truck "illegal" with the duals exhaust, it also does not have mud flaps- which any truck lifted above stock height is required to have here. to top it off my bumpers are almost a full inch higher than legal as well.

When he got it inspected every year...its normally $15 in this state.. he ended up having to pay $20.00. I know the guy that he went to, and have already discussed with him getting it inspected this spring. for $5 I'm not going to spend the time for $$ to fix the stuff- or take off my exhaust.

whats that old saying It's not who you know its ....oh never mind!!

Brandy
 
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