[Cliff R]

"We are experiencing some knocking on slight acceleration and as we raise the RPM's up. Why?"


Don't want to be the one to remind you but with the pistons in backwards you just might be hearing piston "slap" instead of "ping" or detonation.

Remember I'm the only one who provided a DIRECT example of actually installing 8 pistons in the WRONG direction and running it 10,000 miles before engine noise, oil consumption, and just knowing something was fundamentally WRONG with the engine drove me to remove it and do an inspection. When I discovered than the Hy-Duty 400 SBC pistons were all facing the wrong direction I knew I had found the culprit.

Good damn thing I didn't have the Internet or a Forum to run to with my issues. I might have ran into some "guru's" or self-proclaimed resident experts that would have told me a few old school racers did that move for their Stock Class racing engines WAY back in the day and that it doesn't hurt anything. Far as I'm concerned it's a "wives tale" and NOT a good move at all, since putting them all in the right direction IMMEDIATELY cured ALL the issues I was having with that engine and I went on to run it in my K-5 Blazer nearly 200,000 more miles as that was my main transportation back in those days and I was commuting over 100 miles back and forth to work every day, plus took it to the Outer Banks nearly every weekend surf fishing, and 1200 mile round trips from my duty station back to my home town to visit family half a dozen times a year.

I considered that very costly experience early in my learning curve a good one that I will NEVER repeat.

Bottom line here Mike, no matter what you have heard or been told, factory type pistons with offset pins absolutely MUST be installed in the right direction for a street engine, or there will be noise, and other issues associated with the pistons flopping all around in the bores instead of staying perpendicular to the crankshaft centerline and cylinder bores like the engineers intended for them.......FWIW........

[TRADERMIKE 2012]

Originally Posted by Cliff R

"We are experiencing some knocking on slight acceleration and as we raise the RPM's up. Why?"


Don't want to be the one to remind you but with the pistons in backwards you just might be hearing piston "slap" instead of "ping" or detonation.

Remember I'm the only one who provided a DIRECT example of actually installing 8 pistons in the WRONG direction and running it 10,000 miles before engine noise, oil consumption, and just knowing something was fundamentally WRONG with the engine drove me to remove it and do an inspection. When I discovered than the Hy-Duty 400 SBC pistons were all facing the wrong direction I knew I had found the culprit.

Good damn thing I didn't have the Internet or a Forum to run to with my issues. I might have ran into some "guru's" or self-proclaimed resident experts that would have told me a few old school racers did that move for their Stock Class racing engines WAY back in the day and that it doesn't hurt anything. Far as I'm concerned it's a "wives tale" and NOT a good move at all, since putting them all in the right direction IMMEDIATELY cured ALL the issues I was having with that engine and I went on to run it in my K-5 Blazer nearly 200,000 more miles as that was my main transportation back in those days and I was commuting over 100 miles back and forth to work every day, plus took it to the Outer Banks nearly every weekend surf fishing, and 1200 mile round trips from my duty station back to my home town to visit family half a dozen times a year.

I considered that very costly experience early in my learning curve a good one that I will NEVER repeat.

Bottom line here Mike, no matter what you have heard or been told, factory type pistons with offset pins absolutely MUST be installed in the right direction for a street engine, or there will be noise, and other issues associated with the pistons flopping all around in the bores instead of staying perpendicular to the crankshaft centerline and cylinder bores like the engineers intended for them.......FWIW........

check OUT POST 516, SOME NEW LIGHT ON THE SUBJECT, the flexPLATE IS DAMAGED, FALLS UNDER THE UMBRELLER ON MY DAMAGES DRIVE SYSTEM, AND YES WE WIIL ADRESS THE BACKWARDS PISTONS , BUT i WOULD BE LYING IF I told you that was my existing problem. However, your diagnostic is viable, you already know why I think otherwise. Sorry I am not writing this over. I have been up 24/7.