exhaust cross over (heat riser) fill

[Mark Yacavone]

Originally Posted by dartman

Heat riser passage may be
blocked from intake manifold side of cylinder head. Blocking
passage down in valve pocket prohibited.

I use thick tin between my intake gasket and head as i was told by the tech guy that pouring in is prohibited

Kelly, I do this process for one of the premier shops in the country. You CAN fill and separate the exhaust crossover in the head.In fact, the newer LT1 style head has this feature, unlike earlier SBC heads.
On Stockers, I place a cotton ball, saturated with plaster of paris into the exh. hole from the port side. I push it in about 3/16ths so there is no question about it being in the port.
This does not hurt the flow ,I have been told .I then fill it right up from the intake side, and then grind off excess.
On bracket engines , I fill from the port side ..in one side ,until it comes out the other port, then grind and smooth, as others have stated. It really helps to put about a 1/16 th air bleed hole in your block off plate.
I have been using aluminum and a home made ladle ,and a cutting torch.
I will look into the zinc deal. Thanks