Can I use this block?

[drfromnc]

Found a bare block while cleaning out my dads shop. It’s a 59 series , relieved block and I have got the head, intake and oil pan surfaces cleaned up. I don’t see any cracks but I do see a few questionable things. See circled places in my pics. Looks like when someone pulled head studs they also broke out some material around the one of holes and another one looks like it has a thread insert. Can I use this block for a rebuild? Also does the S2587 stamping mean anything?

[Bored&Stroked]

Looks like it could be a good usable block . . . probably came from a race engine back in the day. Looks like it might be ported as well. If it was mine, I'd take some further steps to figure out exactly what you have and what condition it is in - before making any purchase decisions related to it.

Nobody can tell you that it is a good usable block -- it needs to be cleaned, magged then pressure tested and then sonic tested. Be prepared to put $500 into it - just to see if you can use it. This is a better approach than believing it is good . . . only to find out the hard way afterwards, that it is not. Also, measure the current bore diameter. Feel free to PM me with questions.

Also, you should let folks know WHAT your planned usage actually is . . . would help with answers.

[drfromnc]

Looks like bore is 3.20” using a cheap digital caliper. Don’t know my plans yet for it other than want to save it just in case I want to rebuild a flatty with mild cam and other goodies down the road to swap in my 34 pickup that I am about to start putting back together.

[rotorwrench]

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3.1875" would have been stock bore for a 239 CID 59 series motor so that one may have a good bit of wear. Relieving is a practice that has lost popularity over the years due to the additional thinning of the already thin deck area with less than adequate benefits for the work performed. They generally work fairly well with the aftermarket aluminum heads that have crow foot shaped chambers.

If it passes inspections as previously stated, it could still be a decent street motor with cam & valve train mods. The center bolt may or may not be a problem. It just depends on condition of the remaining threads. These motors can use head studs or bolts but had studs originally. Most of the numbers on flathead engines don't have any known meaning other than date codes that are sometimes stamped in the rear right intake deck location. The big 59 casting mark is the only real identifier for the post war engines through 1948. Some are 239 CID and some are 221 CID but the 221 blocks show some prewar characteristics plus the smaller bore size.