Quote Originally Posted by Robyn View Post
Oh yesssss
I bought the kit with the inserts, the drill and the special tap.

The inserts have special threads that are angled up and they "pull" pull the crack together.

The idea is to stop the crack from spreading and to maintain proper torque on the bolt.

IS IT PERFECT.....NO.....But this fix has a good track record.

I have done a couple 6.5 bottom ends..

Welding cast iron is a tough slog even when the casting can be spotlessly clean and contaminate free....

Oil soaked casting is just a loosing battle......

I assume the crack is in the outer bolt hole ???

As you probably know...GM reduced the bolt diameter in the 6.5 outer bolts to 10mm from the original 12mm

This does leave a bit more material in the area....but cracks still happen.
Yes, the crack is on one of the outer holes. Plain as day to see it. Didn’t even wipe it down.

I do not plan on any more disassembly until I get lab results done. I have test tubes on the way for samples. I can tell you are extremely excited to see the results. :-D I am too!

Do you still have any of the tooling stuff you used? That guide plate you made?

Thinking ahead of the game…

If I removed the larger exhaust valves from the Redheads and had a machine shop install them on a set of AMG heads, what are your thoughts about that? Lower Egts, faster spooling, less drive pressure? Etc… Of course I would put brass between the valves to compensate for the material loss with the higher chance of the AMG’s cracking.

Also I do not like the idea of boring a 6.2 Redblock so 6.5 pistons could be installed. I can not seem to find any 18:1 6.2 compression pistons, so it seems Twisted Steel is my only option for 18:1 6.2 pistons. I can get ONS 6.2 pistons cheap and send them off to Twisted.

I remember reading a thread here where members cut up 6.2 and 6.5 pistons to check thickness. I can’t seem to find that old thread.