I am trying to determine if a 3904351 block has been decked or not. There is no VIN or build date stamped on the pad [suppose to be an unstamped pad]. I was told that as a rule of thumb, if I measure from the top water pump bolt hole [top inside] to the surface of the pad and it measures .200 that I can assume the block has not been decked. Can anyone tell me if this procedure is correct, or is there another way [other than going off the rotating assembly] and what the correct measurement for a block that has not been decked would be. Thanks
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Re: Determining if 67 351 block has been decked
First thing I would do is examine the top surface for machine marks. Broached block-machine marks running parallel to the crank from front to back means not decked. Circular machine marks are a decked block.Bill Clupper #618 -
may have been "re-broached"
There are several very clever individuals who are able to reproduce the longitudinal grain pattern. I heard of one it Texas who machines the deck with a cutter. Rumor has it that someone bought the original broach machine at an auction - I don't know how they would get it home as it was supposedly HUGE. That said, most don't do it that way, they just belt sand the pad area alone to "re-texture" it. In that case, you will see a small step-off where the belt sanding begins. If they use the belt sander to remove the old stamping, this step is quite deep (maybe .010") and you can see where the head gasket is "floating" above the deck surface at the end of the head. To reduce this step, they frequently deck the block to remove the original stamping then only sand the pad about one thousandth of an inch or less - just enough to add the grain. In that case, the remainder of the deck will have circular broach marks including several areas that stick out beyond the heads on the side of the block.
Good luck,
MarkComment
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Re: may have been "re-broached"
I was anticipating that we would be looking at a bare block with the entire deck exposed.Bill Clupper #618Comment
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