D- or round dish pistons for Iron CJ's (460)

Planning to get custom pistons for 460 Iron CJ build. Have a choice between different dish shapes for adjusting the compression ratio. Which type of dish to get, having the choice?

Calypso wrote:Planning to get custom pistons for 460 Iron CJ build. Have a choice between different dish shapes for adjusting the compression ratio. Which type of dish to get, having the choice?

"Reverse Dome"

Thank you.

It depends on how much volume you need. 20 or more might have to be round. The diameter of the round dish is the critical factor versus a "mirror image" dish.

duplicate post

gt350hr wrote:   It depends on how much volume you need. 20 or more might have to be round. The diameter of the round dish is the critical factor versus a "mirror image" dish.

Good point. What I need for 10-10.5:1 is 10-15cc dish.

Out of curiosity, is it preferable to keep the round dish diameter in the small side to retain squish/quench, or will it work better with a narrow squish band?

The "minimum" I use is .375 wide. I found that out courtesy of my former Nascar customers. We did allot of testing when we were doing the spherical dish program back then. Less that .375 liked to detonate easier. The squish is certainly more critical on cast iron heads than aluminum and much less critical when "boosted".

gt350hr wrote:   The "minimum" I use is .375 wide. I found that out courtesy of my former Nascar customers. We did allot of testing when we were doing the spherical dish program back then. Less that .375 liked to detonate easier.  The squish is certainly more critical on cast iron heads than aluminum and much less critical when "boosted".

Thank you. Are you (still) in the piston business?

Yes but I don't go on forums to promote the fact. I am here to learn and help when I can. PM me if you like about my day job.

Calypso wrote:

gt350hr wrote:   It depends on how much volume you need. 20 or more might have to be round. The diameter of the round dish is the critical factor versus a "mirror image" dish.

Good point. What I need for 10-10.5:1 is 10-15cc dish.

Out of curiosity, is it preferable to keep the round dish diameter in the small side to retain squish/quench, or will it work better with a narrow squish band?

At that volume, even weight isn't an issue. Reverse Dome.

+1 dish volume is low enough that an inverted dome would be better with the quench pads.

Curious about even weight. When does that become an issue and why?

Calypso wrote:Curious about even weight. When does that become an issue and why?

As more depth is required, the piston deck has to be increased to accommodate.

Two things happen. First, at some point the weight increases more than you might like, second, the space available for the rod is decreased.

Either way, those of use that "design" pistons can do anything we want....as long as Newton agrees.