>When cylinders are re-bored there's supposed to at least be a mock head attached and fully torqued to spec to ensure correct results when assembled.
that's not usually true, and it'd be pretty difficult to achieve without a different jig for every engine.
When I spent time in the engine shop, we used a mag-table/mag-chuck for steel parts, and we used table vices/clamps for the rest of it. We would start with inspection and disassembly, move on to parts-holding, and then finally we'd bore/hone/surface, in that order.
There is a 'mock head' installed in that the piece is being held to the work surface, but other than that it's not typical to add more structure when machining -- it makes things much more difficult to move around.
For (very) high performance engines, some manufacturing processes require the engine to wear an external girdle before finish; but it's not too common elsewhere or in the aftermarket world.
For flow-benching head I've have seen the head bolted down like you're talking about, but for that they're trying to approximate an engine's flow.
Are Cummins B series diesel engines considered "very high performance" [1]?
While use of the torque plate in re-boring is apparently more optional than I thought, the point stands; these things aren't ncessarily square when unassembled and the original manufacturer of warrantied engines is going to take distortion into consideration when machining the new parts.
On an unrelated note; EVs can't take over fast enough, good riddance of all this archaic ICE junk.
that's not usually true, and it'd be pretty difficult to achieve without a different jig for every engine.
When I spent time in the engine shop, we used a mag-table/mag-chuck for steel parts, and we used table vices/clamps for the rest of it. We would start with inspection and disassembly, move on to parts-holding, and then finally we'd bore/hone/surface, in that order.
There is a 'mock head' installed in that the piece is being held to the work surface, but other than that it's not typical to add more structure when machining -- it makes things much more difficult to move around.
For (very) high performance engines, some manufacturing processes require the engine to wear an external girdle before finish; but it's not too common elsewhere or in the aftermarket world.
For flow-benching head I've have seen the head bolted down like you're talking about, but for that they're trying to approximate an engine's flow.