dome pistons

i got a set of dome pistons with two releave vales what side do i put up the dome side to the top or to the botton where the spark plug is .

Dome to the plug side. The pistons should be marked with an arrow that points to the front of the motor. Pistons are manufactured with the piston pin offset to reduce piston slap in the bore, so the manufacturers indicate the front with an arrow. You can't install dome pistons backward because the dome would hit the flat area of the head, but you can install flat-tops or dished pistons backward. The result is a noisy motor.

If you're having your machine shop assemble the pistons on your rods, they will orient the piston to the rod, then it's up to you to install the rod correctly on the rod journal, with the chamfered side of the rod toward the fillet side of the journal and the oil hole in the rod big end pointed toward the cam to oil the lobes.

Have a mechine shop remove the old pistons and install the new ones on the rods, most shops around here dont charge too much to do this and they will do it correctly and mark each one with which cylinder they go to :)

Better to give the shop a small fee now then to have a major repair later and a much larger fee