T. ingermanson - Has anyone tried the Gandini piston shown above and actually checked the piston deck to combustion chamber clearance?
Whats the C.R. of the Gandini piston shown above and what's the link to the page showing the C.R.
The 500 piston I have has a compression height of only 38.5mm but the Gandini is 42mm. That would seem to put the Gandini piston into the cylinder head. And 77mm skirt length seems very very long. Something is off.
I don't have them, but have communicated with Obsolete Bikes in the Netherlands about getting some in the past.
No first hand knowledge of the high CR pistons they refer to as "Dunstall", nor the "standard" 88 CR pistons. This is what they said about the Dunstalls: "
The dimensions they give are: 42.069 mm plus 4.8 mm. I think the main from centre of gudgeon pin hole to the edge of the piston and the 4.8 mm is the size of the dome."
Ostensibly, they are measuring the CR with the downdraft SS head, but that's just an assumption, and zero idea about what valve pocketing may have to happen for that dome.
Would rather have your pistons than theirs, truth be told, but that doesn't help much in this instance.
I do have a plethora of 88 pistons, starting with low 7:1-ish CR, up to some 11:1 (reported) Powermax super dome craziness with monster valve cutouts with hard, sharp edges all over the crown.
Also some stock original pistons from a Mercury, but not sure if they're the same CR or not as the 650SS. I can give those a look and measure, if you think it would be helpful to you.
