Thread: Catalytic converter question?

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Is this thing supposed to go on in a certain direction?There is no markings for inlet ,and outlet.

Originally Posted by BigTruckDriver

Is this thing supposed to go on in a certain direction?There is no markings for inlet ,and outlet.

it don't make no dif.!!

i think with some monolithics, the direction does matter because it has different catalyst material in different places that need to be hit in order. i've always seen the air tube in the middle point forward after it bends 90*. i cannot swear to these things, but it's what i've heard.

if there is no tube then it makes no dif. if there is a tube, put it back the way the tube was on the old conv.

I have never read anything about cats needing to be on a certain way but have turned them around and had a major difference in NOx reduction. I install them like this (if there isnt an air tube stand it up so the part number is not unside down. the top of the cat goes to the front). I dont know if NOx reduction is important in Texas but I think NOx the only emissions affected by a backwards cat.

Originally Posted by lt1s10

if there is no tube then it makes no dif. if there is a tube, put it back the way the tube was on the old conv.

let me start over again. most conv. are direct bolt on, or have a tube , so there is no question how they go, but with the unv. muf. shop conv. you can put them on most any kind if way, E.P.A. put a # on all conv. sold across the counter, and when you install the conv. you are suppose to put that # so it can be read standing under the car while its up on the lift. there is a post card in the box with the conv. that you are suppose to fill out and send to E.P.A, to let them know that you changed that conv. i believe if it made a lot of dif. which way it went on then they would have made it harder to install.