Cracks in block


Sharpest Tool
Jul 11, 2010
Western NY state 315 er
Willys Model
Willys Year:
I went to the machine shop to have a look at the block.He made a light pass on the milling machine to clean up the block deck prior to doing the valves.This is an F head four cylinder.There's evidence of a past "stitch"crack repair near the two center exhaust valves.Of more interest is two small cracks,one each coming from the two center exhaust seats toward the valve side of the block.They are about 1/2 inch long.The two center exhaust valve seats were replaced sometime in the past.The machinist sees he sees this frequently on old engines,usually a result of being run hard or maybe overheated.He said the cracks appear old He doubts that a new stitch repair will work so close to the valve seat area..He also said most guys will run the motor with a cracks and see no problems.This engine didn't have coolant in the oil or exhaust gases in coolant.The block will need to be bored,the valve ground.Of course there's no guarantee the cracks won't get worse.I'm squirming here debating dumping money into this suspect block. And of corse there no guarantee another block won't be cracked unless it's been Magnafluxed or milled . What to do..................
Hhmmmm...the proverbial rock and hard place. This may not mean much, but here is what I would be tempted to do, and just might end up doing in spring when I take my block in.

I would "probably" do the most INEXPENSIVE rebuild possible and run with it, while keeping the hunt going for another "hopfully running" decent engine and try again.

Like I said, that probably doesn't help much, but...
Best of luck to you. Let us know how it all pans out.
It all depends on the cracks... I tore apart my 60 Mav's Hurricane 6-226 and found this: