Gutting C4 Pre-Cats ???
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Gutting C4 Pre-Cats ??? (autotech)
Nope, never heard of a way to gut a precat without cutting it out and gutting them then welding back in.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Gutting C4 Pre-Cats ??? (autotech)
Considering where the pre-cats are located it would seem very difficult.
Anyway, a big part of the restriction also comes from those little 2 1/4" waffle-bent pipes that were used.
The best remidy is to have a good exhaust shop custom bend & weld up a 2 1/2" mandrel-bent front Y or get one from MAD.
Anyway, a big part of the restriction also comes from those little 2 1/4" waffle-bent pipes that were used.
The best remidy is to have a good exhaust shop custom bend & weld up a 2 1/2" mandrel-bent front Y or get one from MAD.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Gutting C4 Pre-Cats ??? (autotech)
The front Y bends just below the collectors and again rearward whter the two pipes blend into the single pipe that mates with the cat.
Check the bends in those areas; if they are smooth and not compressed in pipe diameter then you could just cut off the pre-cats, gut them and weld them back.
Check the bends in those areas; if they are smooth and not compressed in pipe diameter then you could just cut off the pre-cats, gut them and weld them back.
Thread Starter
Racer
Joined: Oct 2003
Posts: 273
Likes: 0
From: Midland Texas
Re: Gutting C4 Pre-Cats ??? (65Z01)
I have a heliarc but I feel you would have to weld everthing in position to get it to fit properly, and that aint happinin with a heliarc. In other words, take it to the muffler shop...Or, tack it together in place, take it off to weld and reinstall.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Gutting C4 Pre-Cats ??? (autotech)
My front 2 1/2" SS Y was custom built and I believe that's what they did.
On the rear they simply cut a section from each Y and welded it up on the car; what a supurb pair of welds too.
On the rear they simply cut a section from each Y and welded it up on the car; what a supurb pair of welds too.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
Re: Gutting C4 Pre-Cats ??? (autotech)
If its the same as an 87, it can be done. It just isnt worth it. I spent an entire Saturday with a hammer and a bent 3/8 stainless steel rod knocking out the guts. A real pain. I did it so I could keep it looking as stock as possible. It can be done but I dont reccomend it unless you have more time and patience than$$$$. :chevy
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