2.5" Manifolds?

[L31MaxExpress]

My '94 C2500 ecsb (7200 lb GVWR) 5.7 had them as well. Discovered this when I was pulling the Y-pipe and broke a few manifold studs, figured weather was cold, I'd just swap some other manifolds on instead of fighting the broken studs. Nope. The others were 2", so I went to work pulling the broken studs and replacing them. Not sure if "all" TBI 2500's and 3500's had the 2.25" as the other examples I had at the time were different combos or the engines were already removed and sold, and I sold them complete with manifolds.

Richard

Makes sense. Although those were probably 45* exit on both manifolds. The G-van logs have the older 70s style exit where the driverside is straight down between cylinder 5&7.

 

[kennythewelder]

I know you said, you dont want headers, but. I have had my Summit brand shortys on my truck for 7 or 8 years. Engine bay heat is never an issue. It did take a little tweeking, but I havent had to replace my header gaskets in 3 or 4 years. First off, people but cheap built headers then have issues. The flanges on mine are 3/8" thick. I learend to use Fel-Pro header gaskets, and to torque the hell out of the header bolts, the re-check them within the first few miles after the engine has heated up, and cooled off once or twice. Long tube headers will give you more bang for the buck, but are more of a PIA to install.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[L31MaxExpress]

I know you said, you dont want headers, but. I have had my Summit brand shortys on my truck for 7 or 8 years. Engine bay heat is never an issue. It did take a little tweeking, but I havent had to replace my header gaskets in 3 or 4 years. First off, people but cheap built headers then have issues. The flanges on mine are 3/8" thick. I learend to use Fel-Pro header gaskets, and to torque the hell out of the header bolts, the re-check them within the first few miles after the engine has heated up, and cooled off once or twice. Long tube headers will give you more bang for the buck, but are more of a PIA to install.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

I had the same set of headers on a 1980 C10 for about 4 years. Pulled them off and added long tubes, had them coated and ran them on the Express van for a couple of years. I had a weld finally crack at which point I put the Thorleys on.

 

[PlayingWithTBI]

I got the Summit Racing G9015 (2-1/2" collector) for my truck because I have the stupid A.I.R. (smog pump) system. I wound up putting insulating sleeves on the back 2 plug wires because the slant plugs got them too close and melted the boots. I agree with @kennythewelder, you need to re-torque after a couple heating cycles.

You must be registered for see images attach

And this JBA 2831 SY mandrel bent Y pipe. Shown with the high flow Thunderbolt 3 cat

You must be registered for see images attach

 

[Erik the Awful]

Again, thanks! I watched the Brzezinksi video then looked up the LT1 manifolds. If anybody else wants to look them up, they're '93-97 Camaro/Firebird manifolds. RockAuto currently only has the right side for $45-65 depending on brand. I don't like the idea that the driver's sides won't get a bolt in that last hole.

Also: https://www.castheads.com/manifolds-carb/exhaust-manifolds/exhaust-manifold-faq/