Strange 318 Block

mchartier105 said

Also to the poster who mentioned something about possibly thicker cylinder sleeves, heres a picture through the freeze plug on the side if that helps, they do look close, but I don't have another block to compare it to.
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That's a good observation, stick a feeler gauge in there and check the gap between the 2 cylinders after cleaning it off a bit, .100" ths or so ?

Looking pretty stock to me, but another member may have an open stock block he could measure for you so you can compare. Then you can put your mind at ease to what it is.

That R on the Block, will keep an eye open if I find out what that means in the future can let you know.

Nice stock block you have there all things considered.