Shelby#18 wrote:Well we have poor results on the pistons. From the new pistons we received we only had a 9.625 compression. We are now going back and getting another set from a different supplier. Guys when this is done hopefully it will save some of you the time and trouble we have been going through. Delays, delays, delays... It looks like we'll have completion sometime this summer of the restoration.
Rick, do you know to which point the machine shop is referring to with their "deck height" numbers? Are they refering to the distance of the top of the piston step to the cylinder head?
If that's the case, the listed clearance numbers would not be satisfying from a racer's standpoint. Best air fuel propagandation and performance is achieved by tight quench areas. Optimum would be zero deck clearance.
I'm talking about this area marked yellow.
If the piston manufacturer knew the exact length of the intake side block height, then he could build a zero deck height piston. If you order it with a slightly wider step area then you would have enough meat to machine off according to the desired compression ratio.
It's always easier and less expensive to machine or grind off ,material from a piston than ending up w. a lesser than optimum compression. Oh, well trial and error.
Let's hope the other pistons will be closer to your desired compression ratio.