Thorley headers heat

[tmsnyder]

I read that to mean you'll move one of the 2 existing mufflers to the back and you'll keep the other as a spare.

Please confirm as some are reading it another way.

I'm definitely reading it the other way, but your way makes more sense Richard. Thanks for the clarification. (reminds me of a joke, next time we're together I'll tell it lol)

 

[tmsnyder]

Just a quick note regarding intake gaskets:
When I was by Jim K's place last summer, I mentioned to his tech that I had messed up my install due to the front seal slipping out of place and my not noticing it. He told me that "they never use those" and that silicone sealant is their choice. Seems that has become the go-to for sealing that area. My 4.3L boat motor (GM) replacement gaskets don't even include that one. RTV used their now (and lots of it).
Anyway, that will make it significantly easier to drop the manifold down when you have the manifold gasket (I used the tub tub style), sealant around the ports, AND sealant on the block off plates. Should be "one shot, one kill" as long as you line it up right when you "simply drop it in place".

To get the alignment on the first shot, cut the head off a 3/8 bolt and thread that into the hole (driver's side?) where the intake has a notch cut into it instead of a hole for the bolt. That notch will get you lined up front to back and side to side, you just need to drop it into place parallel with the engine.

And yes, throw the rubber gaskets in the trash. My friend is a long time mechanic and racer, extremely knowledgeable on the BBO told me long ago those rubber gaskets for the front and back of the valley are junk. He recommended using a complete tube of Ultra Black RTV, half on the front and half on the rear. (This is for when installing block off plates in the FelPro style gaskets, one on left, one on right. Not for Turkey Tray style gasket)

 

[Billygoat]

I read that to mean you'll move one of the 2 existing mufflers to the back and you'll keep the other as a spare.

Please confirm as some are reading it another way.

Correct, thats what I thought was the setup with a muffler in the back, am I wrong in that understanding?

 

[pvfjr]

Correct, thats what I thought was the setup with a muffler in the back, am I wrong in that understanding?

Just to clarify, if I'm correctly reading what the confusion might be, here's the factory setup. Each bank gets its own muffler, which is why we can get away with 2.5" mufflers. Then they Y together downstream, and there's one long, continuous run to the tailpipe.

If you were to have a muffler after the Y, you'd need to upsize it since it's flowing for all 8 cylinders rather than just 4, and there might not be enough room for one that tall unless you get fairly creative/custom.