How much is to be gained by removing the original cat?

[pizza442]

I could tell on my 79 H/O that the stock system and cat were pretty restrictive even for the R code 350 and even more-so with a plugged bed/bead cat. I owned it around '87-90, 54k orig miles and in mint Calif condition, but someone had replaced the dual-outlet crossflow muffler with an incorrect single outlet so I got into the Walker catalog and ordered up a correct one (saw the illustrations for the diesels with the dual outlet muffler and 'missing' cat part of the exhaust which was interesting to see/discover) Anyway, you could hear the restrictive exhaust when you floored it so IMHO there is at least some power there to be opened up.

Wonder how it would've done with the 83-87 cat-back system? I wanted to do that but no $$ at the time.

 

[azmusclecar]

I could tell on my 79 H/O that the stock system and cat were pretty restrictive even for the R code 350 and even more-so with a plugged bed/bead cat. I owned it around '87-90, 54k orig miles and in mint Calif condition, but someone had replaced the dual-outlet crossflow muffler with an incorrect single outlet so I got into the Walker catalog and ordered up a correct one (saw the illustrations for the diesels with the dual outlet muffler and 'missing' cat part of the exhaust which was interesting to see/discover) Anyway, you could hear the restrictive exhaust when you floored it so IMHO there is at least some power there to be opened up.

Wonder how it would've done with the 83-87 cat-back system? I wanted to do that but no $$ at the time.

Yes lack of funds is always my limiting factor, trying to stretch the dollars buying used parts and searching for the best buys.
My H/O revs up but seems to hit a point where it's just trying to breathe in more and I feel the exhaust is holding it back.
I'd love to put a nicely done dual cat back system on mine but as the lead in to this post says, money is the key...

 

[olds307 and 403]

My 1979 Hurst Olds with the 350 still has it's OEM CAT, with 83K on it. It has a small hole in it and I was just thinking of having a straight pipe
made for it and eliminate the CAT altogether.

I may end up patching the hole in the OEM Cat if the cost of a straight pipe is cost prohibitive. I'm in an emissions exempt area.

Quite a bit. I changed the high mileage unit with a straight pipe on my 81 Delta 88. The reason, I lost a close race to a Mercury Mistake, um Mystek. He wouldn't race me again, I would have won, a noticeable difference. Put on dual exhaust, the Olds crossover pipe is a joke along with that big restrictive cat, kills power.

 

[LeftLaneOnly]

Blew out a donut on the drivers side and it seems to be choking, going to open the connection at the cat . If it runs better I'm putting in a straight pipe this weekend.

 

[pontiacgp]

It is easy to check to see if a cat is plugged or restricting the flow by taking the in and out temperatures with a temperature gun

 

[azmusclecar]

It is easy to check to see if a cat is plugged or restricting the flow by taking the in and out temperatures with a temperature gun

Well I just happen to have one..............just how much of a difference shouldl I see in your estimation?

 

[azmusclecar]

Blew out a donut on the drivers side and it seems to be choking, going to open the connection at the cat . If it runs better I'm putting in a straight pipe this weekend.

I blew 2 donuts out that is why I thought my CAT may be blocked....just replaced the 2nd donut...now I'd like to find the cause.....I love donuts
but not the kidn we are talking about.

 

[pontiacgp]

Well I just happen to have one..............just how much of a difference shouldl I see in your estimation?

on a good cat it will be cooler in the front than in the back

 

[Supercharged111]

Newer factory cats are superior to 49 state aftermarket cats. Scour Craigslist for LS takeoff cats. I got some off of a C6Z Corvette that are going on my 1500 if I ever find the time to redo it's exhaust.

 

[pontiacgp]

Newer factory cats are superior to 49 state aftermarket cats.

where did you read that?... 🤔