I have a flathead with a crack in the block in two places. Both cracks are between a water jacket hole and a threaded head bolt hole. The head bolt hole is open to the water jacket on both cases. I see no visible cracks between any of the cylinders and the water jacket. My question is this block useable as is? I am trying to post a couple pictures of the cracks.
If the cracks you mentioned are the ones I think they are, they are known as "part number cracks" because they are so common. They are of no consequence. Of all the flathead blocks I have been through, I have only seen two that did not have at least one of those. Just use a good thread sealer on the bolts/studs.
I tried to look at the pictures but got a "H.A.M.B. Error". I will say the cracks from the water passages to the bolt holes ONLY are not a problem. Pictures always help, though. BTW, just because you can't SEE any other cracks doesn't mean they aren't there. The only way to be sure is to pressure test the block; ofttimes, there are crackes hidden in the exhaust passages or pan rail that aren't visible to the naked eye.
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