[Mr_GTO]

Have it rebuilt by a PONTIAC GUY. Take it as a lesson learned.

[Big Injun]

Originally Posted by Mr_GTO

Have it rebuilt by a PONTIAC GUY. Take it as a lesson learned.

You have a great local resource in Ken Brewer at Pacific Performance Racing at 310-832-4596.

As for your pistons, you can mill a grove the depth of the valve reliefs. I have done that on another 400 and it works great.

[Bruce Meyer]

Excessive oil consumption WILL cause detonation. If those are forged Speed-Pros they CAN be dished. HO racing used to dish them and sell them right out of their catalog. Get a new machinist!

[67bonnie455]

I am not convinced detonation took out the bearings. It certainly would not be from leaking valve guides. Think of how many motors are running with worn out valve guides and no bearing failure. If the mains show scoring I would still be thinking oil pressure. If the mains are perfect, then I would be thinking rods too tight or maybe detonation.

The kind of detonation that can hurt bearings comes from NOx not set up correctly. We sold hundreds of 231v6 motors and they didn't run correcly unless they spark rattled loudly like you were going to break a piston. No bearing damage. I think the kind of compression damage to bearings would have shown other problems like hard to crank or locking up, severe spark nock, etc.. That my experience so I am just not convinced it was detonation.

I asked about the lifters thinking of a problem with the oil pressure to the bearings. (like solids without restricters). Does anyone know if you can put in the wrong cam bearing?

The other thing I thought of is a plugged oil filter. After breaking in a coated cam, you need to change the oil filter or it becomes restricted. The last thing is an exploded oil filter. I have seen this take out a motor. With the oil filter bypass plugged off, if the oil filter is not flowing properly, oil pressure to bearings suffers. The gauge showing pump pressure before the filter.

A few thoughts.