So been trying to figure out this motor for a while.. Recently put a cam in and broke it in accordingly OOW. When I put it in water it was bogging not running great, it opened up for a while but then bogged down and died. Tried starting again and it went POP very loud a couple times.. would not start after that.

Will turn over for days like the kill switch is yanked but will not fire, occasionally coughs up some white smoke which scares me..

Valves were in spec, just pulled heads thinking could be gasket or rings but gaskets were in good shape and there is not oil on top of pistons.. there is some carbon accumulation though, would rings blow in an instant like that? Could it still be rings without having oil on the cylinders? What else could this be??

Any help is appreciated!

If the rings are hurt you shoud be able to see cylinder wear lines or something there. Did it still have fire? Any chance it flooded bad or sheared timing key?