Re: [AMC-list] exhaust ports...

[Frank Swygert <farna@xxxxxxx>]

Yeah, that's a good concern! Temps will be in excess of 600° coming out the port.  Could you go to 1/4" for the top? I don't think you'll eat through or melt the plate, but warpage will be a concern that I didn't consider when I replied. You've put a lot more thought into it, more than the 10 minutes I did before replying!

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Date: Sun, 7 Feb 2010 20:52:34 -0800
From: tom jennings <tomj@xxxxxxx>

On Sun, Feb 7, 2010 at 08:41, Frank Swygert <farna@xxxxxxx> wrote:

> Just the opposite -- sounds well within reason. I don't think I'd worry
> about the furnace cement though. Since the insert will stay in place by
> shape, don't worry about a little exhaust gas or heat rising into that well.
> You main concern is flow, right? At anything above idle exhaust gas velocity
> will be increased to a point that a small "crack" along the leading edges of
> the insert won't matter.

Actually I was more concerned with heat, eating the relatively thin (3/16")
steel roof filler plate. I figured with hot gases on only one side the metal
wouldn't cook. Cast iron has poor heat transfer and is much larger mass and
has a water jacket under it. My steel roof will be thn and right in the
exhaust.

I also figured if it warped from heat then it could lift up and get
hotter/warped-er... because I'd like this to be a one-shot deal and not do
some long term development I prefer gross overkill. But I might just weld
the three pieces in-place and be done.

Tabs welded to the plug and a ver small milled notch on the head would let
the manifold retain it and only reduce the gasket area 1/8" on two small
spots.

--
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)

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