bondospecial

My 87 N/A car has original cats and the previous owner complained of the pre cat glowing. I am going to look into the fuel end of things as well to make sure that is not the result of an over rich mixture but, this exhaust is also on its last legs and has some holes in it. I weld and I think I am going to make a new exhaust myself from mandrel bends and pipe sections. I intend to keep a catalyst system (I have really bad allergies and I do not want a car that reeks of unburned exhaust) but I would like to replace the multiple cat converters with one single, high quality cat. If I do this, I assume I would get one cat that has an air pipe to maintain the stock A.I.R. function as well?

Thanks

Steve

gracer7-rx7

iTrader: (16)

the stock cats are actually very high quality and do a great job. the piping sometimes causes a restriction since it isn't always as smooth as it could be (at least not on the FD).

If FC Pre-cats are like FD pre-cats, they do tend to clog. I'll wait for the FC experts to chime in. Most of the time pre-cats are generally to aid cold start emissions so you should be fine with just a good main cat. Not sure if that is enough to pass emissions in your state though.

bondospecial

The car does not have to pass emissions, 20 years old and older in MD is historic. I have historic plates on the car so no inspections or emissions inspections of any kind. All my older fun stuff is registered like this.

Thanks for the info on the pre cats. I will take the exhaust apart this weekend and see if a visual inspection lends anything

funkjaw

iTrader: (3)

If your engine is running well enough, even with no cats or air pump it will not smell terribly bad at all. However one main cat is fine as most the time the pre cats are clogged to all heck anyways. I ran only one main cat on my NA with an air pump for quite a while. It even passed smog with flying colors like that.

bondospecial

^ok that's what I need to know, that's what I was thinking, one cat with AIR. I am pretty sensitive to rich smelling exhausts making my chest congested (backing my roller cammed 350 chevy powered Firebird out of the garage irritates me, that thing has no cats smells terrible) so I am going to want it catted no matter what. Plus it's better for the earth right!

Thanks for the help guys

Steve

gracer7-rx7

iTrader: (16)

^I disagree. The smell bothered the hell out of me on my NA FC, Turbo II and my FD w/o a cat.

One main cat should definitely do the trick if you don't have to worry about emissions.

funkjaw

iTrader: (3)

To be honest for me it depends on what oil mixture I am running. When I was running whatever I can get my hands on or even idemitsu rotary racing oil my car would burn more oil and with no cat it would smell and irritate my asthma as well.

When I run 4 quarts VR50 plus two bottles STP oil treatment my car doesn't smell that bad at all and burns less oil even with my cat less exhaust.

On the emissions note most FCs will pass fine without the two pre-cats... I know this because I am a smog tech that works next to a rotary shop.

gracer7-rx7

iTrader: (16)

I don't doubt you. My opinion of smell, sound, spicy etc is probably different from yours.

Given your description, I guess you work next door to Rotorsports

funkjaw

iTrader: (3)

^^ Yeah. Come by and say hi!
I work the weekends.

masa_3100

iTrader: (1)

Hey im just about to buy a NA FC 86 and im just worried about it passing smog. so from my understanding it can pass smog easily with just one cat and doesnt require the pre cats? The one im about to buy seems to have passed smog twice from 2006, and it has had a rebuild from about 75000 miles ago.

gracer7-rx7

iTrader: (16)

If I understand CA laws correctly.... (I'm new to cA)

The seller is required to smog the car prior to selling to you. If it doesn't pass, its their co$t to get it to pass. Otherwise its your problem $$. There are plenty of FCs out there.

funkjaw

iTrader: (3)

Technically it is the sellers responsibility to have the car pass smog prior to selling it. However there are ways around this so they don't have to comply with the law.

Now the car has a good chance of passing the sniffer with just only a main cat and air pump hooked up, but by law it needs all original cats on it to pass the visual portion of the test. However most techs will just see a big main cat under the car (thats if they even look) and will just pass it visually.

If you are scared you can always bring the car by my shop and we can check it out.

masa_3100

iTrader: (1)

Ill definitely drop by your shop later if it has any problems. Im relieved that there is a rotary shop near my place, I was having nightmares of driving it to somewhere far off when its going to be my daily driver!