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

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.

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.

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.

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.

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.

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.

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.

Re: Lets talk Catalytic Converter positions
 

My '89 K3500 Single cab/single rear wheels has the cat behind the exhaust near rear axle

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.....

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)

Re: Lets talk Catalytic Converter positions
 

Couldn't find the Suburban, but the 3500 checks out. Converter behind the muffler.

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?

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.

Attachment 1759620

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".

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

Re: Lets talk Catalytic Converter positions
 

You guys are posting exhaust for trucks. The OP has a suburban.

Re: Lets talk Catalytic Converter positions
 

Yup, thats the way mine is. But the muffler and cat have been replaced at one time. Have never seen this before. I think I will move it before the muffler. I still cant understand the reasoning behind a 3 yr span of putting it after muffler as I dont see any difference in floor plans, crossmembers, wiring etc.. from other years or from a 7.4 TRUCK.

Re: Lets talk Catalytic Converter positions
 

We are very aware of that fact. We're in Kali. That is also a fact. At one time there were 49-state vehicles and there were Calif. only vehicles that were optioned with EGR, AIR, etc. that 49-state vehicles were free of. Maybe that Sub was originally a 49-state vehicle (?).

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.

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.

Re: Lets talk Catalytic Converter positions
 

What sort of transmission mount - cross member did you get?