Cylinder head bolt holes that have broken into the intake port due to porting or CNC.
Any pros and cons about inserting a brass tube into the head bolt hole to prevent vacuum leaks or oil into the port.
I have installed the tubes in the past, but wonder if it is really necessary in a NA application.

This message has been edited. Last edited by: Bruce Williams,

not an expert but suggestion is go ahead and do it.have seen them pull oil.

Thanks Rusty.
Depending on how well the head bolt washer seals against the head would determine if oil can seep past and port vacuum suck it into the engine.

bruce i am sure some run without the tubes ,i have also.you just have a lot better chance with tubes.good luck

I thought I read a post at one time from Chad Speier where he said that he usually doesn't use them and it isn't a problem.