My 406 cracked a cylinder. The crack is fairly visible but I have a feeling it could be repaired. I called a few machine shops and asked about a sleeve and they said they could weld the cylinder (cracked toward center of bore thru to steam passage) and sleeve the cylinder. Some shops say that will hold fine and some say it will be too weak.

I was thinking of having it welded and sleeved but also doing a half fill of hard blok to strengthen the cylinder(s). I wanted to get the expert opinions from here before I waste time or money. Will be street driven, occasionaly hard, but not strip use. Not a daily driver.

What do you guys think?

 

if you can't find another block, or have a lot of jack tied up in that one i wouldn't worry too much about the sleeve.

 

The sleeve will hold. A friend of mine has a 406 in a 72 chevelle taht reuns 11.00 at 119 MPH. The motor has TWO sleeved cylnders due to a cracked block. He has no poroblems with overheating or performance, and he does not use any blockfiller.

IMO I dont think you have to worry about the sleeve.

 

Is the crack through to a water jacket, or just the steam hole? Are you positive it doesn't extend through to an adjacent cylinder?

The only block I've ever had to sleeve was a Pontiac 400 V-8, and it worked fine through a boat-load of abuse afterward.