Yesterday after finally getting my exhaust fixed I got the car to idle on its own for the first time in 6 years. The cat was bad so I got a new one put on and had the line from the air pump attached as well. I thought things were great.

Fast forward to today: The car was idling very high, 3-4k rpms. I had adjusted the idle screw so I though that was the problem although the car would seem to accelerate itself. I get home and pop the hood in order to adjust the idle screw and I see the header all the way back to the new cat bright orange. You know the orange that looks like it is super heated. I also have the heat shield on around the header with that cotton packing stuff around it but it was so hot that it caught fire! I had only driven the car for about 20 minutes and this has never happened before. What does everyone think is going on? Talk about scare the crap out of ya, you know.

 

damn u must have a lot of backpressure which is causing that maybe ur new cat is defective....i wouldn't drive it like that

 

So is that probably the problem then???

 

Could be running very rich being that it's carbed.

 

No, the leaner the air fuel ratio is the hotter the exhaust temps. So it would be running too lean. Lean is not good.

 

So adjusting my air/fuel mixture on my carb should fix the problem? Then the exhaust isn't the issue?

 

Would a too lean condition make it idle high though?

I'm wondering if your ignition system is alright. I know that a very late spark, or retarded timing setting, can burn your exhuast up pretty fast. I don't know, but I'll be interested in hearing how you finally solve it so please keep us posted.

 

hard to say for sure, but richen it up and see what happens first. If that doesn't work check your cat, for what I dunno, it shouldn't be clogged already....

 

Was the cat designed specifically for a rotary? I think I heard that a normal one will burn up and clog in short order.

 

I don't think it is designed for a rotary but I've only put about 100 miles on it since it was put on. I'll richen it up and see what it does.

And yea, Would a too lean condition make it idle high though?

 

You just need to richen it up, then lower the idle speed. The idle screw is about an inch or two to the right of the mixture screw on a nikki.

 

Ok, richened up the car and completely screwed in the idle screw but it still idles at about 4k. I pulled off one of the wires that went to the distributor, the one closer to the firewall, while the car was running, and it slowed it down some but only to about 3k. I'm completely lost as what to do next.

 

PM'd you.

Rich