Need info on (97) vortec exhaust manifold flanges (downpipe flanges)

[Ricky8680]

Howdy boys. If anyone has some stock manifolds handy,could you get me the measurements of the 3 bolt triangle flange that connects to the downpipes of the exhaust pipes on a vortec truck? Correctly working on redoing my exhaust,but the hoe is my daily and I don't have the time to break it all down to measure it. So specifically,the 3 bolt pattern of the triangle,and the hole inside,so I can order the correct adapters to build my exhaust with. Or if anyone has a part number already,that'd be sweet too. Thanks in advance!

 

[Schurkey]

on a vortec truck?

Vortec? WHICH ONE?

4.3L, 5.0L, 5.7L, or 7.4L?

 

[Ricky8680]

Vortec? WHICH ONE?

4.3L, 5.0L, 5.7L, or 7.4L?

My bad,5.7,1997 one specifically,k1500 with the small headpipes

 

[jjupiter100]

are you building with shorties?

 

[Erik the Awful]

Well, if TBI manifolds are similar, I measured 2.1" inside diameter with an estimated 3.3" bolt circle. It's 25* outside so I wasn't gonna dork around, but I'm assuming it's intended to use 2" exhaust tubing with a 3.25" bolt circle. Since it's a conical flange you might get away with 2.25" tubing if you can still fit the bolt circle.

 

[Schurkey]

My '88 K1500 uses a 2.25" donut. Fairly sure that's stock size, although I don't have stock manifolds any more. The headers have a 2-bolt flange.

Photo 1. Fel-Pro 9998. http://hbassociates.us/K1500_Exhaust_Donut_01.jpg

You must be registered for see images attach

But I don't have a Vortec small-block to compare.