Rod Knock

[tbalcome]

Ok I am running this combo! 1994 block 1988 head

4.6L "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons (.030)
9.25:1 CR
Stock 4.0 HO camshaft
Ported HO 1.91"/1.50" cylinder (head 88 head)
Mopar/Victor 0.043" head gasket
0.088" quench height (.093)
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
248hp @ 4900rpm, 303lbft @ 3500rpm

Broke in just fine with the recommended 20 minute cam brake in! Changed oil and took for test drive! Jeep started to sound like a diesel.

Took pan off checked main rod bearings and everything was just fine. Pulled head and found cylinder/piston scoring.

When assembled all tolerances where in check!

[stege123]

Bad luck.
Please send pictures so it is easier for us to determine cause of trouble.
I'm reading your specs, and you used 020 pistons and are writing 030. I consider this a slip of the pen.

Many people do the break in of the cam correct, but forget to break in the piston rings. Did you break in your rings??? Gap of your rings OK.

Was the engine overheated?? Was all the removed antifreeze replaced with enough antifreeze??

Please be more specific and send some pictures

[Cheromaniac]

Pulled head and found cylinder/piston scoring.

I see you used +0.030" pistons which is fine, but did you use +0.030" rings? Something's seriously wrong here and some pics might help.