Reason for brass screw on intake.

[Beltfed]

Purchased a dirty and well used intake manifold last week, three stud carb.  Decided to run it through my grit blaster to get the burnt on whatever off and make it pretty.  Going to have it planed next week.  Notice while blasting it that there is a brass screw about 1/4" o.d. on the side of one of the runners.  Believe it is foward of the carb and on the driver side.  Just wondered what it's purpose is.

[larry butcher]

Show a "pic" of this manifold, I may know what it is, Also before you spend a lot of time on this pc, check real good underneath for "rot out" due to moisture and acids eating away the 

aluminum  -Larry

[peecher]

The brass screw is actually a brass plug. There should be 2, one forward of the carb and one to the rear of the carb on the left side of the manifold. These  plugs are used to cover the access hole drilled in the side of the manifold to drill the "equalizing" holes in the inner division wall between the left and right  intake runners.

[Beltfed]

Attached are two pics of the manifold.  One is hopefully showing the two screws, yes they have slots.  The other is the under side which I looked at after reading Larry's post about "rot out".  The bottom looks good enough to me that I'm thinking taking a few thousands off will make it good to go.  The pencil is pointing to one of four hole with something in them.  It acts like carbon but might be fossilized rubber.  Any idea on that?  Thanks

 

dang, where the pictures go?

Edited September 8, 2016 by Beltfed (see edit history)

[Beltfed]

had to remember how.

[peecher]

It's probably carbon. The hole is for exhaust which heats the riser section in the manifold.

[38ShortopConv.]

Hi Beltfed, haven't heard much from you lately ,thanks for the speedo drive pics for the Columbia, its all assembled, installed and back in 38 LZ conv. now.
Yes it will be carbon filling up  those 4   holes in the hotbox inlet manifold riser. The exhaust  heat from the  4 holes on top of the block travels up into the riser and stops the carburetor icing up in really  cold weather. You can clean them out carefully then sit manifold upside down overnight, fill those 4 holes with water and see if the level drops indicating an exhaust  leak into the fuel air area of the inlet manifold.
LZ motors don't run too well if hot exhaust gas is getting mixed with the fuel air system.
If there is a leak you can block those holes off with welch plugs, engine may hesitate in cold weather till warms up
. Nuff for now.