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03-03-2018, 10:56 AM | #1 |
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Lets talk Catalytic Converter positions
On my 94 Suburban 2500 7.4, 2wd, my cat is AFTER the muffler just before rear axle. It looks fairly new, but my smog test, I just squeaked by by points of failing on 1 part(i will have to look which one).
I thought a cat needed to get HOT to be efficient? If I put in closer to the front, where does it go? Thanks
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------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
03-03-2018, 10:58 AM | #2 |
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Re: Lets talk Catalytic Converter positions
It should be ahead of the muffler. I'm surprised it passed, as strict as they are. They are staggered on the pass side, under the foot board/seat.
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03-03-2018, 11:19 AM | #3 |
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Re: Lets talk Catalytic Converter positions
Mine is a single(94). the y-pipe is stock and has not been cut. I have seen a couple others this way, but I dont understand the reasoning behind it. I plan on moving it forward, but need to see pics of stock locations.
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------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
03-03-2018, 02:08 PM | #4 |
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Re: Lets talk Catalytic Converter positions
No oem cat has ever been installed after a muffler, period.
I have the oem service manual, all 4 books and like 3000 pages worth.
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03-03-2018, 04:42 PM | #5 |
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Re: Lets talk Catalytic Converter positions
Every 92-95 3/4 ton suburban that I have worked on had the cat at the rear behind the muffler.
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03-03-2018, 05:14 PM | #6 |
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Re: Lets talk Catalytic Converter positions
Is there a reason they are behind the muffler? Can they be put in FRONT like all the others? Or is something in the way or what? I looked under mine and dont see any reason it cant be moved, but GM did this for a reason that I dont understand.
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------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
03-03-2018, 05:41 PM | #7 |
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Re: Lets talk Catalytic Converter positions
That really defies logic since a cat has to reach a certain temperature before it will even work. The only unit I'm aware of installed after a muffler is a resonator.
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1989 K1500 Chev. EC Original owner; some of the aftermarket parts I've installed are Borla headers, Hypertech chip, Edelbrock water pump, and a Stillen rear disc brake conversion kit. 2009 Hummer H3T 3.7L 5M (sold) 1997 K2500 Chev. EC 7.4L/ 4L80E 2018 Dodge Ram 2500 HD R/C |
03-03-2018, 06:11 PM | #8 |
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Re: Lets talk Catalytic Converter positions
I'll get some pics of my walker catalog when I'm at work on Monday.
I should have clarified earlier, the only ones I work on are big blocks. Small blocks may be different. Last edited by 95 S_Trucker; 03-03-2018 at 06:17 PM. |
03-03-2018, 09:31 PM | #9 |
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Re: Lets talk Catalytic Converter positions
My '89 K3500 Single cab/single rear wheels has the cat behind the exhaust near rear axle
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03-04-2018, 08:33 AM | #10 |
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Re: Lets talk Catalytic Converter positions
I had 2 454 1 tons 88 and 89, both were in same location, under pass side, before muffler. something doesn't make any sense.....
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03-04-2018, 08:09 PM | #11 |
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Re: Lets talk Catalytic Converter positions
My original Cat is stuck above the transmission cross bar & has a "32 of an inch of room, above / below. I need to change it & move it past the tranny support.
It actually rests on the support... ( exhaust is kinda old)
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03-04-2018, 11:34 PM | #12 |
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Re: Lets talk Catalytic Converter positions
Couldn't find the Suburban, but the 3500 checks out. Converter behind the muffler.
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03-04-2018, 11:50 PM | #13 |
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Re: Lets talk Catalytic Converter positions
I just dont understand why though. Its my understanding the cat needs to get to a certain temp to operate correctly. Why did they only do this for a couple years and then go back to the forward position?
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------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
03-05-2018, 07:09 AM | #14 |
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Re: Lets talk Catalytic Converter positions
I couldn't find anything on my walker catalog, which tells me that walker isnt making the parts to keep a factory exhaust on these 92-95 K200 Suburbans with the 7.4
I did look up this picture on my 92 light truck service manual. This was in the suburban section. 8600 GVW with the 7.4. It clearly shows the converter behind the muffler. |
03-05-2018, 08:03 AM | #15 |
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Re: Lets talk Catalytic Converter positions
Maybe this will help. I scanned this pic out of my '89 Chev truck shop manual. Maybe this cat is some type of "afterburner".
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1989 K1500 Chev. EC Original owner; some of the aftermarket parts I've installed are Borla headers, Hypertech chip, Edelbrock water pump, and a Stillen rear disc brake conversion kit. 2009 Hummer H3T 3.7L 5M (sold) 1997 K2500 Chev. EC 7.4L/ 4L80E 2018 Dodge Ram 2500 HD R/C |
03-05-2018, 09:21 AM | #16 |
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Re: Lets talk Catalytic Converter positions
This is from my service manual. ( C2500 5.7 )
I don't know why they needed to jam the converter between the tranny support
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'70 GTO Midnight Blue '88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany. '93 Cadillac STS Black '93 Mercedes SL 500 Teal '86 Yamaha FZ750 - 15,000 RPM '86 Yamaha FJ1200 - Criminally Fast 2016 Ferrari 488 GTB, I drive it - don't own it. '05 GMC Yukon XL , SLT 4wd ( just purchased 2018) |
03-05-2018, 09:25 AM | #17 |
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Re: Lets talk Catalytic Converter positions
You guys are posting exhaust for trucks. The OP has a suburban.
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03-05-2018, 10:32 AM | #18 | |
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Re: Lets talk Catalytic Converter positions
Quote:
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------------------------------------------------------ -Lance 2000 Chevy C2500, 5.7, 4L80e 1999 Suburban K2500, 7.4, 4L80e 1980 Camaro..son's car...PROJECT |
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03-05-2018, 12:18 PM | #19 | |
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Re: Lets talk Catalytic Converter positions
Quote:
The big question is why the cat is where it is since the cats normally require heat shielding and heat of 600-800 degrees to work. Even Calif. doesn't require cats on old cars with new engine swaps because the old cars didn't have heat shielding under the pass. area.
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1989 K1500 Chev. EC Original owner; some of the aftermarket parts I've installed are Borla headers, Hypertech chip, Edelbrock water pump, and a Stillen rear disc brake conversion kit. 2009 Hummer H3T 3.7L 5M (sold) 1997 K2500 Chev. EC 7.4L/ 4L80E 2018 Dodge Ram 2500 HD R/C |
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03-05-2018, 03:39 PM | #20 |
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Re: Lets talk Catalytic Converter positions
I had the same problem with my converter laying on the tranny crossmember. I replaced my transmission mount and now I have plenty of clearance.
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1988 Chevrolet C1500 RCSB |
03-05-2018, 03:55 PM | #21 |
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Re: Lets talk Catalytic Converter positions
What sort of transmission mount - cross member did you get?
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'70 GTO Midnight Blue '88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany. '93 Cadillac STS Black '93 Mercedes SL 500 Teal '86 Yamaha FZ750 - 15,000 RPM '86 Yamaha FJ1200 - Criminally Fast 2016 Ferrari 488 GTB, I drive it - don't own it. '05 GMC Yukon XL , SLT 4wd ( just purchased 2018) |
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