Here's mine.
I have a rebuilt engine and am having hell getting the exhaust manifold to seal after the first cylinder at the bottom.
I am also curious if the exhaust preheat valve could be sticking and causing additional back preasure.
It is not sticking, but what if I wired it open?
The first picture is at rest with the manifold warm, the second the spring is under slight preasure to hold in that postion.
I have a really quiet muffler on it, so I expect I have some back preasure anyway.
I put the second gasket on and it did not seal at all, looking for ideas.
I thought I read that you must put the intake and exhaust on together but not bolted up, tighten everything, then tighten the preheat cavity.
Also looking for a tuning schematic for the 1BBL carbs if you might know where to find one.
Mike
CUSTOMAL@FLASH.NET