- Joined
- Aug 3, 2010
- Posts
- 30,095
- Reaction score
- 27,231
- Location
- Usually not in Ohio
- First Name
- Andy
- Truck Year
- '77, '78, '79, '84, '88
- Truck Model
- K5 thru K30
- Engine Size
- 350-454
Magnoflo. I did a LOT of research when I put this together. See post 41. I'll try to dig up the part number for that cat. It was slightly different from the rest in that it is CA rated. All that means is it has more catalyst and cleans the exhaust better than the same non CA version. Still a high flow unit.
Some pitfalls to avoid. It needs to be hot to work. The hotter the better. The closer you can get it to the Y-pipe flange the better. My first Y-pipe was 2-1/2" diameter. Big mistake. It shed heat way to fast, I remade it with 2" and the difference was noticeable. Ceramic coating or wrapping the Y-pipe would also help. Since I shi*t canned the headers and used the Holley Manifolds (ceramic coated) it solved the issue.
I understand the small y-pipe and single converter, it makes sense for heat. What confuses me is why GM went this route on a lot of trucks/vans, but on others, they had large (like 2.75") pipes into dual converters, sometimes with one of the converters mounted all the way back by the muffler. Any idea on that?