CIS & Cat Bypass

[3rd_gear_Ted]

Are there any reasons a CIS motor can't deal with a cat bypass? I would like to install one to eliminate the heat a cat converter causes.

[SteveinTO]

That's what I did on my '82. Works great. Make sure you get one with a bung for the O2 sensor if you have one. You may want to tweak the A/F afterwards as mine seemed to do more popping & farting on decel. It may make just a bit more noise, but not much. Hard to tell.

[AzTarga]

Did it on my '81 . Works fine , sounds great .

[joe payne]

No problems and gives the stock muffler a nice throaty sound.

[jasonlee]

cat bypass on my 82 SC with CIS. No issues at all. a little popping on decel, but sounds cool

[glewis80SC]

No issues on my 80SC, +1 on the 02 sensor hole.

[3rd_gear_Ted]

Thanks gang, Just wanted to be sure those CIS hybrid circuits from the 80's have the ability to deal with the change. It appears that all the CIS controlling is done up front on the intake side with pressure sensing & flow rate control.

[Peter Zimmermann]

Originally Posted by 3rd_gear_Ted

Thanks gang, Just wanted to be sure those CIS hybrid circuits from the 80's have the ability to deal with the change. It appears that all the CIS controlling is done up front on the intake side with pressure sensing & flow rate control.

Be aware that in CA your car will not pass smog with the bypass on the car. It will probably pass the visual, but the cat is needed for the tailpipe test.

[Joe Bob]

Typically a 3.0 can pass with SSI heat exchangers. At least mine did when I convinced the guy they were dual cats.....

[3rd_gear_Ted]

Your right about putting the Cat Converter back in there for smog testing in CA. Thats where the anti-seize on all the bolts comes into play.