What modifications would be necessary to fit these to an Avalanche 2500 (8.1 L)?

 

Should fit just fine in the Avalanche platform, basically same application as the truck.

 

I had a problem with mine they hit the steering shaft. There is a spot on the shaft that is made to collapse in the event of an accident and it hit there. So instead of denting the headers which i think is hack, i cut out that piece of the shaft and welded in a pipe of smaller diameter. Basically i sleeved it. The only thing i can think of as to why it hit is that the 2500hd sits higher up on the frame to clear the trucks with allison's, putting the steering shaft at a higher angle. Other than that they fit great i love them.

Alex

 

Thanx for the first-hand experience. I don't have the equipment or knowledge to weld, so dimpling the header would be my only option. That sucks because I wanted a coated header (and I also think dimpling the header is a bit ghetto). The search continues...

Thanx again!

 

According to your signature your heads are milled??

If so this will change the overall fitment of the header, any header for a big block is going to be a tight fit and if its a larger primary headers tolerances will be much closer. A milled head will change the exhaust port location and effect fitment. Glad you were able to make it work!

 

The heads are milled .040. The part of the steering shaft would hit it no matter if they were milled or not. I did not think it was too big of a deal to do what i did but granted i have to tools to do it. I am not sure if you guys have changed the design of the headers at all. I bought them in 2006 right when they came out. I have brand new motor mounts in the truck as well. It may just be my truck, we all know none of these trucks are all exactly the same. It may even be because I took the whole cab off the frame because i restored the whole damn thing so it may not be dead nuts on. This is just my experience with my truck. I wouldnt take it as there is no way they will fit.

Alex

 

Do you know if these will fit on the older BBC trucks? 3/4 ton square body to be exact..

 

Honestly not really sure if they will work, I'm sure they may bolt to the block, but not positive on the clearance around the steering and the primary's clearing the frame. The angle of the collector could be different before entering the mid pipe location. What year truck do you have?

 

91 3/4 ton 2wd Suburban. Frames are similar from the late 70s to 91 on the 3/4 ton trucks and Burbs.

The reason I ask, is there are zero decent headers out there made specifically for these trucks. I refuse to put junk headers on a vehicle and I've had experience with SW in the past, so I know they are reliable and good quality.

 

For 8.1 Performance Check our friends at Raylar Performance, they do magic with the GM Big Block and man we cannot get enough of this amount of power.

Watch Video



01-03 Chevy/GM Truck-8.1L
2001-2003 Chevy/GM Truck-8.1L
2" Primary Tubes
3" Collector
Uses Factory Headpipes & Catalytic Converters
Fits: Sierra 3/4-Ton, Silverado 3/4-Ton

04-06 Chevy/GM Truck-8.1L
2004-2006 Chevy/GM Truck-8.1L
2" Primary Tubes
3" Collector
Uses Factory Headpipes & Catalytic Converters
Fits: Sierra 3/4-Ton, Silverado 3/4-Ton



Stock exhaust manifolds reduce exhaust flow, reducing power and economy. Headers promote better scavenging, improving exhaust flow, increasing efficiency and power output. Our performance kits increase your engine's ability to breathe and will show maximum gains when coupled with long tube headers.