This is a 383 I bought and the guy said it had never been run. It has been together for over 10 years just sitting in the guys garage. It is a nice old school build - 906’s, 509 cam, TM-6, Demon 850.

I have searched the internet and can’t seem to find any details on this piston. I saw one on Mancini’s site that seems to have the same shape of relief in the picture, but the description said it was a 5cc relief. I am just having a hard time believing that is 5cc relief. I am going to try to roll it on its side tomorrow to see if I can at least get close to measuring, but thought someone on here probably knows exactly what it is.

Thanks

It looks like a custom piston with additional valve notches cut into them

fill the reliefs flush with the surface with clay then roll it up out of there & with your burette filled up pretty high to say 60 CC with water, kneed/roll the clay into a long rope with your palms then drop it into the burette & see how far the water rises. It for sure looks way more than 5

Looks like a kb162 Kieth Black piston.

That was the first thing I thought too.

If you look at Summit it will have extra wedges cut out in them , but over the years they have changed the configuration around. Look at Hughes web site and they have a picture of the older version like the ones you have.

Telltale Keith Black pistons.

KB 162, and it is rated 5cc relief. Basically a stock piston replacement. 8.6 comp with a 90 cc head, 10.2 with a 72cc head.

Thanks for the help, KB 162 it is. I was able to match up the picture on the Hughes site. I decided to measure and they are in fact 5cc relief.

more compression than a Sealed Power- Badger, etc stock replacement "destroked" piston
most of those are/ (now were) Flat tops)
no quench with open chamber 906 heads- tough to make this combo ping proof but big cam should help- but you loose mid range torque (which is why it may not ping)
check those heads out for guides and ex seats- stock valves?

Put a set of them in the '70 383 HP engine I rebuilt 10+ years ago. Only set that gave any reasonable amount of compression. Still ended up decking the 906 heads down a good bit.