My '56 A10's conrods have the numbers on them (possibly casting numbers not part numbers) of 67-270 R272R (has oil hole) and 67-270R3R and are 6" long - are they the correct rods?
My 56/57 parts book lists the pr numbers as 67-1203 and 67-1204.
I've not seen the engine I'm rebuilding run, but the seller said it ran fine. I have stripped it down anyway as it had hardly been used in over 30 years. It's got quite a few problems but the strangest is that it had a 3mm compression plate fitted under the barrel, but high comp style pistons. Pic attached.
The pistons have over 006 clearance at the bottom but have nevertheless partially seized in the past, which is a (expensive) pain as the cylinder has already been lined. I think the sleeves might b be too badly marked to re-use. I'm puzzled at to why it has seized and am looking for reasons...apart from the conrod with the oil hole being fitted to the wrong (timing) side!
The barrel is thick flange whereas thin flange would have been standard for 56 model year
The stroke of the crank is right at 84mm, so at least I have the right crank - I think.....it is small journal type and on -030 big ends, -010 main
It seems that 6.5 inch long rods are used on at least some A10's and I can't see why shorter rods would be fitted on a 56 model given I've read the thin/thick A10 barrels are inter-changeable - unless the cases are shorter on some models? Or different pistons fitted on some models?
The pistons are flat topped domed type (typically 8.5:1 look like these I'm told) and measure 1.334 from the gudgeon pin center to the start of the chamfer on the piston top, and the dome part is 0.175 on top of that. I guess the compression plate was fitted to make the chamfer not protrude too much above the barrel.
