I've been puttering on my 499 engine rebuild for over a year now but I'm finally to the point where I've mounted the 540 Cylinders and pistons to the crankcase.
You may recall that the Nanni Ricambi kit cylinders come with 1.5mm high lip around the bore. Nanni tells me that no gasket is needed with this kit and I can bolt the head directly onto the cylinders. I was skeptical and did some measurements and calculations of the C/R, but I assumed that the deck clearance would be zero. (See my post: "Foreign Object Damage" for the whole story.) Now that the cylinders & pistons are in place I see that the deck clearance of the piston is, in fact, 2mm! See photo below: the pistons are at TDC.
Well, that changes everything.
My revised calculations for C/R with no gasket (as advised by Nanni) is 8.54:1;
My revised calculations for C/R with a 0.5mm copper gasket is 8.15:1; and
My revised calculations for C/R with a 1.0mm copper gasket is 7.80:1.
It looks like I don't really need a gasket to get a reasonable C/R. I don't trust that my head is flat enough to assemble it onto the cylinders without something there to seal it.
I'm thinking that I can go back to Tom's (The Hobbler) suggestion in the previous post of using Wellseal on the lip with no gasket.
Alternatively, I can source a very thin copper sheet, maybe 10 mil (0.25mm).
Are there any opinions on the better way ahead?
You may recall that the Nanni Ricambi kit cylinders come with 1.5mm high lip around the bore. Nanni tells me that no gasket is needed with this kit and I can bolt the head directly onto the cylinders. I was skeptical and did some measurements and calculations of the C/R, but I assumed that the deck clearance would be zero. (See my post: "Foreign Object Damage" for the whole story.) Now that the cylinders & pistons are in place I see that the deck clearance of the piston is, in fact, 2mm! See photo below: the pistons are at TDC.
Well, that changes everything.
My revised calculations for C/R with no gasket (as advised by Nanni) is 8.54:1;
My revised calculations for C/R with a 0.5mm copper gasket is 8.15:1; and
My revised calculations for C/R with a 1.0mm copper gasket is 7.80:1.
It looks like I don't really need a gasket to get a reasonable C/R. I don't trust that my head is flat enough to assemble it onto the cylinders without something there to seal it.
I'm thinking that I can go back to Tom's (The Hobbler) suggestion in the previous post of using Wellseal on the lip with no gasket.
Alternatively, I can source a very thin copper sheet, maybe 10 mil (0.25mm).
Are there any opinions on the better way ahead?
