Bore Engines in All Applications
All arrangements of 4.75" Bore engines now use a spacer plate between the cylinder block and cylinder head. The former block had counterbores machined in the top surface for the cylinder liners to fit into.
The former 2P8774 and 2P8776 Service Block Groups with a counterbore design are canceled. The new 6N8127 and 6N8124 Service Block Groups will be used for parts service of the former block groups. On most engines, except the early vehicular engines, either the former counterbore-type head assembly or the spacer plate head assembly can be used with the new block group. The chart shows which service parts to use for each head assembly.
The 6N7725 and 6N7727 Hardware Kits have miscellaneous parts that are necessary for the installation of a new cylinder block group. The 8N6273 and 8N6274 Conversion Kits are needed when a spacer plate cylinder block is used with a counterbore-type head assembly.
A spacer plate in the conversion kit has a passage (slot) that takes the lubrication oil from the new location in the spacer plate cylinder block to the former location in the counterbore-type cylinder head. The conversion kits also have the new type thrust plates for the crankshaft.
Special Instruction Form SMHS7541 gives the procedure to use when the former counterbore-type block must be serviced.