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  #1   IP: 24.184.4.248
Old 06-29-2009, 12:12 PM
Fireriders Fireriders is offline
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Question Block surface question

This is my third attempt to get a thread on troubleshooting so I hope it works. After going over the "critical rebuild topics" I find "scribe lines on the head and block with an ice pick". What the??? I've rebuilt gas and diesel engines more times than I can count and never has anyone told me to go at the mating surface with an ice pick or similar tool. Is this something we should really do? How deep? Length or width wise or both? How close should I get the valve seats? Thanks for the help, Fireriders.., second question. The cast iron elbow at the filter screen to pump is cracked. I cant find a cast iron elbow this size. I have a brass one that is the same thread. is this suitable? Thanks again, Jeff aka Fireriders.
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Old 06-29-2009, 03:26 PM
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Don Moyer Don Moyer is offline
 
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Jeff,

If the surface of the block and/or head is worn smooth, the head gaskets will not get a good grip and a gasket failure is possible. The original specification for the gasket surface of the block and the head called for a roughness factor of RMS 120. This roughness is approximately the texture of a metal fingernail file (if you can still find one).

The two critical areas in terms of this roughnes factor are the narrow places (approximately 1/4") between the bores of the two end pairs of cylinders (1&2 and 3&4). It's usually possible to get three scribed parallel lines across these cross sections by using a straight edge and ice pick or awl - in both the deck of the block and the surface of the head. The lines need only extend out past the center of these areas about an inch or so.

The rest of the gasketed surfaces around the combustion chambers are broad enough that failures seldom occur (like between cylinders 2&3) even if the surfaces are quite smooth. The Victor gasket company recommends using the gaskets without sealer.

Don
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