Cracked guide boss in Aluminum head
 

I recently got my LS1 stocker heads back from machine shop and noticed that several of the valve guide bosses were cracked, where the new guides were installed. One is appx one inch down in the runner. My head guy, would rather not mention his name, informed me of this and said it was common. Has anyone ran into this? Is it a problem? Thanks for any info.

Re: Cracked guide boss in Aluminum head
 

It's a GM casting.

Re: Cracked guide boss in Aluminum head
 

they can split when ball sizing or burnishing a guide liner. the ball size can be too large for the liner too expand. always used to sneek up on the size. it should'nt happen if a solid guide is used. either way i was'nt conortable with that situation.

Re: Cracked guide boss in Aluminum head
 

I don't know where you're located but , you could call Jeff, at Modern Cyl Heads, Clinton Township, Mi ! The number is 586.468.7914, or 586.465.2811 ! He's really good !.....Later........John