Catalytic Converters on 1st Gen Camaro (68)

Hi guys,

Posted this on the camaro forum also, but figured their maybe some more input here.

Read a number of posts on the matter. I know everyone has their opinion about cats.

In my case, I have a 350 SBC chev. It has a fitech unit on it. I have a moroso catch can that is doing a good job of removing oil from the PCV - so I have done a number of things to reduce the exhaust smell.

Played with my AFR's. Previous owner installed a big cam in my car, so my AFR's move a little at idle - from 14 to 15 parts. Which is lean.

My wife is a great mother, but goes in to protective overdrive with my kids. Moment any chemical smell is around, paint, cleaning chemicals, or exhaust smell - she goes totally nuts.

Put it this way - I already installed 3 point seat belts and had kids booster seat anchor points all properly certified by an engineer - and she still complains the car has no crumple zones and is unsafe.
That is what I am dealing with. : )

The whole point of having the Camaro (aside from my own joy), was being able to share that with my family and kids. If they are getting out of my car, stinking of fumes any time they are near it, the wife will soon make sure the kids are not in the vicinity when my camaro is running.

So I am now considering Catalytic convertors. My car is a cruiser, not a horsepower hero. From what I have read, the performance is little impacted anyways. I know everyone has an opinion, but my mind is made up - I am gonna try Cats.

My question though....

I have been looking underneath the car, trying to think of the placement, as well as heatshield options. Can't see any images in google search for cats on 1st gen camaro to help.

My key question is about PLACEMENT though.

At this point, best places I can see that will allow for the room, required air gap from floor pan, without impacting ride height (my car is on ridetech coilovers - I like it low), seems to be either the tunnel, or maybe up near the sump.

Has anyone with a low ride installed Cats on a 1st gen camaro? Would love to hear.

I have short headers (sanderson) ready to fit, which should allow for the most flexibility in making up an exhaust, just wondering if anyone can share info about their experience/success/issues.

My biggest concern is cooking my floor pan and ride height. The right heat shield requires enough air gap though...struggling to see where I can make the install happen which will give me the clearances I need + allow me to keep it low.

Thanks in advance.

The 1969 Camaro never had "cats" They werent on cars till 1975 .I believe it would be a waste of money to do so .

Cats definitely make the car more enjoyable. I have had walker high flow cats on my '71 since around 2000 and the difference is night and day.

I dont come in the house with my clothes smelling like exhaust.

My wife is the same way about smells and stuff. So the fact that she'll ride in my car says something. I too have EFI and have it running about as efficiently as possible, but without cats my guess is the exhaust smell would be pretty bad.

My car is about stock ride height though. So even though cats weren't stock in 1971, fitting a couple of small cats under the car was pretty easy.

Completely agree with the difference in smell...I have two LS swapped vehicles, one with and one without. The one without the exhaust smells rich like an old muscle car should and consequently my clothes carry that smell around for days after. The one with cats doesn't have that smell and does not affect performance. I prefer to run the cats after having both.

You can get oval shaped universal cats that come with a heat shield already attached to them. They aren't much "taller" than the OD of the pipe itself. How much room do you have from your current exhaust pipes to the floor, in the area you're considering installing the cats?

Glad you brought this up. This is my plan this winter. I have very little room myself and oval tubing which also poses a challenge. Not to mention there aren't any decent exhaust shops anywhere near me.

I plan on running Magnaflow cats. For my new engine I'll be getting custom shorty headers made and installing the cats right after them (using v band clamps) like on a modern car. Then they aren't so much under the car as tucked on either side of the transmission bellhousing. I also have a SS oval exhaust already made that I'll be fitting after that.

I think the small loss in power and change to the exhaust note are well worth having the cats.

Like Snowcatter said, you won't notice any loss in power. It will get a little quieter too, which I liked. I like having a clean understated car.

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Originally Posted by ULTM8Z

Like Snowcatter said, you won't notice any loss in power. It will get a little quieter too, which I liked. I like having a clean understated car.

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Any recommendations on brand of high flow cats? I have a SBC.

I've had Walker 2.5" cats on the car since about 2000. They've worked really well for me.

I have 2 Dynatech cats on my Olds 442 convertible mounted right after the header collectors. The Dynatech cats have metal substrate cores which are more tolerant of mixture variations than ceramic cores. They also have a spun stainless shells, come in 2.5", 3", & 4" sizes and flow just under 400cfm each. I'm very happy with them and the car doesn't smell like un-burned gasoline. They are bit pricey though at $200 each.

I put some low profile Stainless Works cats on my 63 Chevy II LS swap. They are the metal substrate variety. Night and day difference in smell.

For those sharing their experience with cats (which is great btw, thank you), if you happen to know the cells count/inch (usually they are 100, 200, 300, and 400 cell) please include that as well. The cell count plays a factor in the conversion efficiency. For example, you can get a stainless works for 3" in/out in a 200 or 300 cell (same external size).

Hi guys,

Sorry I have not responded sooner. Appreciate all the information posted here - very helpful. I am not sure on the measurements yet for my own application - I think a lot of that will be dictated by the new sanderson mid-length headers I have, but they are not yet fitted.

I also purchased a new lower-profile transmission crossmember for my 700R4 - so will be able to get the exhaust tucked away more than it is currently.

I first thought I would be fitting Cats right after the collectors. From what I can see, with the new headers - there should be the right amount of space there on both sides of the engine. However - I now realise my fuel lines run pretty close to that space on the passenger side. I know my exhaust gets hot and I am comfortable with the distance from fuel lines currently, putting a Cat right in that location - yeah - with their larger size and the heat they put out - brings it all a little too close to the fuel lines. Would concern me a little. Might have to re-work all my fuel lines to have Cats after the collectors.....rather avoid that.

Then I start thinking about Heat Shielding, the air gaps required, which is all a bit hard to visualise without the headers on and without being 100% on the Cat being used. The spaces and clearances - all start getting tight when you consider "proper" heat shields and appropriate air gaps.

I know the oval Cats incorporate heat shielding, BUT most modern cars would have them fitted AND heat shield underside the floor. Even one of those oval units with heat shield, sitting under the floor - I'm tipping would make the floor toasty.

At this point, I have booked my car in with a good exhaust shop. They know what I want to achieve, but I am not going to know their recommendations until they get my camaro on the lift and start fitting my new headers.

From what I am reading - sounds like Stainless Cats (not ceramic) are the way to go. Will post with how it all goes next week, share the results.

Hi guys,
Finally got my Cats and new headers fitted up. Looks great - shop did a really good job. I only drove it for a short period, but noticed the exhaust smell was decreased significantly. In the end I went with 100 cell cats - only becuase previous ownder installed a large Cam in my engine and I am still working through my fitech adjustments. Thought 100 cell metal would be safer whilst I iron out the EFI gremlins.

I'll take some photos, but in my case - with my 68 camaro and 350SBC + Sanderson Mid-length headers - I am VERY happy with the Cats placement. The headers left HEAPS of room. so my cats are sitting well in front of the transmission, below the collectors. Heaps of room for further heat shielding as well for firewall and floor.

My engine mounts are a little worn which unfortunately mean the shop had to work one of the tubes to clear the PS pump, but it is underneath the header tube, can't really be seen from above the car......that is about the only dissapointing thing, but headers are always a gamble. As from PS - clearances everywhere else are great though. I think new engine mounts would have allowed my headers to clear....so something to keep in mind if you are doing similar.

That really great to hear! The Magnaflows I'm going to be going with are 200 per inch. I have a sorta rowdy cam with Holley EFI.

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Originally Posted by showdog75

I put some low profile Stainless Works cats on my 63 Chevy II LS swap. They are the metal substrate variety. Night and day difference in smell.

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Do you happen to know the length from V Band to the the end roughly?

I have cats on my 66 Chevelle. Not for smell but because it was easier than trying to fool the ECM into thinking they were there when they weren’t. Same with my 67 Chevelle conv.
That said, there are a ton of other smells from a car that a cat won’t affect. In fact I would guess that MOST smells from a car won’t be affected by adding cats. And the smell that would be affected by cats is going out the tail pipe which if properly run would be all the way at the back bumper.
If you have any combustion smells in the cabin you have other issues. Something that cats aren’t going to fix.

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Originally Posted by cpd004

Do you happen to know the length from V Band to the the end roughly?

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I can measure it if you'd like although I doubt it'll do you much good. There is a v-band then a short length of tubing, the bellows, and then the cat. It didn't come as pictured.

I think I'm ok now. Is that flex tube 4"?

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Originally Posted by cpd004

I think I'm ok now. Is that flex tube 4"?

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Yes sir