The purpose of a piston board is to support the pistons and help keep them stationary while the cylinder block is lowered over them.
There are many designs for piston boards, but they don't need to be complicated in order to be effective. The one shown here is about as simple as it gets. I used an old plastic kitchen cutting board, but any scrap of pine board or plywood would work fine.
I began by cutting a slot to allow the board to slide past the rods. Then, with the board in position, I laid a base gasket on top and carefully lined it up over the base studs by eye. Using the gasket as a template I marked the stud positions and counterbored holes about 3/8 of an inch deep. I then flipped the board over and laid it on top of the studs.
The board supports the pistons, preventing them from being pushed down; the base studs engagement with the counterbores prevents things from sliding around. The result is a much easier time lowering the cylinder block over rings and pistons.
Alternatively we can shim up the pistons with sticks and blocks, but the additional stability and security of a piston board make the small additional effort worthwhile.
The piston board shown here also provides a good way of keeping the rods from being banged
around during a rebuild, with or without pistons attached.
N.B. My good friend Lorne informs me that this piston board model will not, sadly, work with Triumph 500 engines due to their shorter rod length.
Below: Cutting board slotted for rods.
Gasket used as template for counterboring recesses for cylinder base studs.
Below, flip board over and position it to engage cylinder base studs.
Double-check for sufficient clearance.
Steady as she goes, and ready for cylinder barrels.
