[Cliff R]

Kenth, do to the way the Pontiac engine is layed out it's more common than you think to find problems with piston orientation and problems with assembly. In most other V-8's the forward most piston in the block is #1. This requires pistons used on that bank of the engine to be installed with the notches on the pistons forward and chamfers on the rods facing the rear of the block, flat sides forward. IF you install those four pistons notches forward and chamfers on the rods to the rear, the other four should automatically be correct when they are installed.

The BIG flag that goes up here is that one piston is running in the block with the notch on the piston facing forward like it should, but seven are wrong....hum? Considering the machine shop should have pressed four pistons in one direction on the rods and four the other direction, it makes me wonder how many rods are in this engine without the flat sides facing each other?

Machine shops even get confused and make mistakes pressing pistons on for them. So between that issue and "builders" assembling them not paying close attention it's pretty easy to make mistakes in that area of the build.

For this build in particular having 7 wrong and one right throws up some flags for me. Plus the OP is complaining about unusual noises. Pistons installed with the offset in the wrong direction is a DIRECT contributor to piston "slap". Piston "slap" never gets better as with the engine I built back in the 1980's with the pistons facing the wrong direction. Mine had an "odd" sound to it from day one, and it got bad enough by 10,000 miles it had to come out. So bottom line here is, that no matter how many folks recommend installing pistons with the offset in the wrong direction, it is NOT a good idea unless you are willing to deal with some of the negatives involved with that move........FWIW......