I have an 89 bronco which i'm going to install a fresh 302 with a roller cam, trickflow heads and a mustang intake and throttle body. I will convert it to mass air but my real question is the exhaust. I want to replace everything and want long tube headers with 3 inch collectors. Then i want to insert 2 high flow cats, 1 each side and exit the tail pipes in front of each rear wheel. I would like to know if it is legal to do this so far as the cats are concerned
Thanks Jamie

 

By the letter of the federal laws it is not legal. The cat can only be replaced if it is deemed burned out or broken by a certified mechanic in writing, and then it has to be replaced with a stock replacement cat in the original location.....However, it really depends on the local inspectors. They are the ones that police the smog laws, and even though the federal laws are specific, the local laws allow for a lot of variance. I currently have to pass fairly rigid smog inspection, but I still replaced my 300 with a 351W and added full length headers, true duals, and two small Dynomax cats. I also run an open element air filter and got rid of my smog pump. The first time I ran it through the inspector, he passed it, but wanted me to re-install the heat riser from the headers to the air cleaner (and...why would you need a heat riser on an open element filter???) So....once again, it all depends on your local jurisdiction.

'82 F150 2WD w/351W (orig 300 I6)
Slik

 

I've heard somewhere that you have to keep the original cat (unless it goes bad, then original replacement required) up until so many miles (50k?), and then it doesn't matter what kind you replace it with. Personally, I don't see why they worry if it is a direct replacement or not, just so it burns clean. Like he said though, check with local inspectors.



88 F-150 4X4 w/5.0 EFI 5 spd
86 Ranger 2WD w/2.3L EFI 5 spd to be 351W 4bbl C4

 

jamiew , go to your DMV office and get you a copy of the state emissions and inspection book. Then you will have all the answers, every state is alittle different
Trouble

 

I used to have a 1991 Bronco with a 302. The exhaust i ran on it was in my opinion the best set up for a bronco. I had JBA shorty headers with 3" single mandrel bent pipe with a highFlow cat all run in the stock location so it would'nt get smashed 4 wheeling