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Hi, guys. I've been working on bringing my 76 back from the dead for about 5 years, I'm getting close. I have a bit of a dilemma, I live in Massachusetts and the car needs a catalytic converter to pass visual emissions inspection. I bought some small, aftermarket cats and I'm hoping to place them just downstream of a set of shorty headers on the fresh small block at about a 45 degree angle to connect with the rest of a dual exhaust system. The car is standard shift and has a Borgeson box. What are you guys running for a nice set of ceramic or stainless shorties? I've tried looking at Patriot or Sanderson but, honestly their websites make my head spin. Any help would be greatly appreciated.
One option is the factory 1981/82 or 84-91 C4 L98. They were solely for weight reduction over the previous cast iron units and are good for about 300 crank hp only. You will have to remove/weld up the air injection/EGR tubes. I used 81/82 on drivers side (with Borgeson) and C4 on passenger side of my '69. I did have to dimple a tube for the Borgeson slightly but plenty of room afterwards. if you hit the right junkyards they are inexpensive, usually pricey on ebay though. They are 409 stainless
Last edited by Dynra Rockets; Apr 1, 2021 at 06:49 PM.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Do You really need to put cats on for a visual inspection down there? I would think you wouldnt have to pass an emissions test being that old. My 68 doesnt get any emissions, just safety. Mass sure has some whacky laws. Maybe contact a car club and see who they other hotrodders use. Can you get something that looks like a cat but is hollow? I used the 2.5 inch Ramshorns for a while, ceramic coated from Summit, they worked really well for the horsepower at the time. I dont think shorty headers are going to be any different. Long tubes will give you a bit more horse on a just above stock build but you will have to either get it custom bent from there back or buy a setup from a vender.
From: At my Bar drinking and wrenching in Lafayette Colorado
In Colorado, all cars 1976 and newer have to pass visual and functional emissions testing. Many States have put 1975 as the last year that can be licensed without emissions, so '76+ Vettes have to have cats, A.I.R. pumps, and EGR systems in place... Very common... The emissions test is stringent enough that most cars will not pass the functional test without working cats, so installing gutted ones aren't going to solve the problem.
Rescue Rogers-
Yes, it has to pass a visual inspection. It doesn't have to have an original cat, or even a functional cat, but it has to have something in place. My issue is not the cat, it's a pair of shorty headers I can attach the cats to. You're in MA, correct? What year is your Corvette? If it's 75 or newer, do you have a cat on it?
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Yes in Mass up north at the corner of Rte3 and 495. I have a 68, guess thats why I didnt know about that requirement.....most of the shorty style headers I had all matched up to the Rams Horn collector and down pipe so anyone you choose would probably work out for you.
Shorty headers
