Ok, thanks for the new info. I was thrown off by the cutaway view in the shop manual that shows the heat being sent up into and around the intake manifold. Now that I look at it again, there may be an interior chamber in the intake manifold that the fuel/air passes thru and a separate outside chamber surrounding it that the rising exhaust comes up into to warm the manifold. BTW, Tommy, I have a NOS exhaust manifold, and it is open at the top where it meets the bottom of the exhaust manifold.
Looking around the Internet, I see Smithys has glasspack and "metal pack" mufflers. I'm not familar with the last kind. When I was a kid, we only had glasspacks: Smithys or Cherry Bombs and I've only heard them on flathead F***s. Anybody out there have experience with the various lengths of either one?
Mick Iniss, I think you're a Smithy's fan.
