Posted by Bob on 09/08/04|
All pistons require skirt clearance so the block is not bored 30 over but maybe 32 over for the needed clearance. The issue I have with boring the engine without the pistons in hand is first depending on the piston you chose to use (cast, hypereutectic, or forged) the skirt clearances will vary and the needed clearance will vary from manufacturer to manufacturer.
Just so you have a reference here is what I would do if the engine was in my shop. Along with the boring I would also deck the block (basically mill the surface where the head sits so there is no chance of a leak when the head is installed)
- I would check the main journals and make sure they are in alingment and if not machine them as necessary.
- I would not even consider doing any work unless you have the crank ground, as most used cranks are out of round or the journals will have a taper on them.
- Get the rods reconditioned and shot peened. This much will get the block done.
- Once you get to this point then you can look at the heads. There is a fair amount of machine work that can be done to heads but the only thing I would recommend is if the machine shop wants to either knurl the guides or install inserts to make them back to standard size.
- A quality machine shop will have the ability to install new valves with an oversized stem so the completed job will be "factory" for lack of a better term.