You said it ran bad , how did it run? Normally i do one side at a time but i just did a top end rebuild, had everything apart, ran the sled & it ran good but no top end..... while pondering things it occurred to me these may be in wrong . is the illustration correct in the placement of the hole facing up. Because i have them the other way facing down, but the way the picture shows in reality the valve comes alot closer to the piston than having them upsidedown. People keep saying in other posts that installing wrong will cause damage, but there is actually 4 different ways to do it wrong & i guess 2 ways that would cause damage.