neutering a cat

[nmurph]

this is a simple how-to about modding a cat muffler. i had one on a 359 that i wanted to MM. i have MM a 359 cat muffler, but i left the cat plate in place and used a 288 deflector. this time i figured i would remove the cat for the MM.

i started with opening the muffler. i have read about opening the crimp with blunt-nosed clippers. i could not get this to work. i also tried heating the seam without success. so, i decided to use the cut-off wheel on a small angle grinder. i cut along the middle of the seam. i had measured the distance from the back of the muffler that thought it work perfectly as this is right in front of the cat plate.

next i used the cut-off to cut around the edge of the cat and removed it.

i used a small cut-off disk on the foredom to remove the exit tube, increase the opening under the deflector, and a small wheel to smooth things out.

one small obstacle to over come with cutting the muffler in half was aligning the support tubes so that exhuast doesn't escape through them. to get around this, i used 3/8"x1" copper coupling. i used the cut-off disk to split and grind. i left a small gap in the coupling and tapped them in place with a set punch. the hole closed nicely and the tension keeps them in place. if you are going to do this, remember to drop the muffler bolts into the support tubes bf you insert the couplings. they will be captive and won't fall out. if you are not concerned with a minor amount of exhaust getting out through these tubes, then this step can be skipped.


then everything was put back together. the muffler was wire-brushed, sanded, painted with 2 coats of grill paint, and baked.

the saw has 0.030 squish. i will probably pull it down and put in a thinner gasket. i may try opening the ports some also.

 

[1steve]

Looks good, nice job. Thanks for the detailed description and pics. Let us know how it works please. And thanks for letting the:catut of the box.

 

[The Count]

does my new 346 XP has a cat?
if I attempt a such trim what I should expect power wise and life expectancy, fuel consumption etc ?

 

[Teddy.Scout]

Pics, description!
Top Notch!

 

[Miles86]

Thanks for these pics, nice job, it will run a lot cooler now.

 

[nmurph]

update

i had a small set back today. i splashed a little mix on the muffler and the paint immediately rubbed off. i don't know what else to do. i wire brushed and then sanded bf i cleaned, painted and baked. i applied two coats of krylon grill paint.
i'm open to suggestions.

 

[ScottWojo]

i had a small set back today. i splashed a little mix on the muffler and the paint immediately rubbed off. i don't know what else to do. i wire brushed and then sanded bf i cleaned, painted and baked. i applied two coats of krylon grill paint.
i'm open to suggestions.

I would suggest you use POR 15 black velvet. I brush the mufflers and then bake them in a toaster oven. The paint is bullet proof.

 

[nmurph]

thanks scott. do any of the big auto retailers sell POR products? i see it on-line, but i would rather walk in and pick it up.

 

[jsk0307]

thanks scott. do any of the big auto retailers sell POR products? i see it on-line, but i would rather walk in and pick it up.

I've never seen it in the big retail stores. Around here it's sold at the automotive paint shops.

 

[redprospector]

Neutering a cat! Hahahaha!
I was going to sugguest stuffing the cat head first into the top of a cowboy boot and go to work with a sharp knife. But I see that wouldn't apply in this situation.

Andy

 

[Winn R]

i had a small set back today. i splashed a little mix on the muffler and the paint immediately rubbed off.
i'm open to suggestions.

nmurph -- It's a little pricey but KG Systems Gun-Kote is available in "Original Black". It's a bake on finish and seems to be impervious to everything.
:smile-big:

 

[JONSSTIHL]

unless I missed it, You don't mention how you got the two halves back together. I assuming tig welded but would like more details. I have a cat muffler from my 2153c hanging around that I wouldn't mind modding. Also assuming you had to cut the two support tubes at the same time as cutting the two halves open.

thanks for the info

 

[hamish]

Another option is to order a non-cat muffler for about $30!

 

[nmurph]

the halves were brazed together. if i do another muffler with the support tubes, i will use a band saw to cut the muffler apart. i ended up with the support tubes at slightly different lengths. i have a table-top band saw, but never use it. it is in the storage shed. it would be perfect for getting everything even. what i did do was, once i got everything apart and cleaned up inside, i used a table-top belt sander to get everything square and even. i think the bandsaw would eliminate this step. the copper tubing was put in just to make sure that nothing shifted and to have a good seal inside the muffler tubes.

 

[SawTroll]

does my new 346 XP has a cat?
if I attempt a such trim what I should expect power wise and life expectancy, fuel consumption etc ?

I thought you instructed your relative there to find a non - Etech one?

Hopefully he did!

 

[SawTroll]

Another option is to order a non-cat muffler for about $30!

:agree2:

That is by far the simplest solution!