Pistons

Chad, The rear wheel bearing seal no. is CR22610. Make sure your shaft size is 2 1/4" and the bore size is 3.565 for this seal to work. I know of two different big bore engines that have been overbored. If you ask my opinion I would bore with new pistons. Bore just enough to clean up the cyl. as you will have to have pistons made any way. Just one guys thoughts.
CORDially Mike

Mike,
thanks for the reply. I know I have to either bore and buy pistons or bore and sleeve, just have not decided which route to go. I do need a favor from you though next time you get home! what is the part number for the modern seals for the rear hubs?

Hi Chad, I can tell you what the Master Parts Book that was effective Jan. 1932 says. Oversize pistons, can be ordered in the following sizes. .010 oversize, .015 oversize, .020 oversize, .025 oversize, .030 oversize, and Semi-Finished. Piston rings are available in standard, .005, .010, .020, and .030 oversize. This parts book is for Auburn and L-29 Cord. It makes no differentiation betwen Auburn and Cord piston size so I am "ASSUMING" all engines can be bored that amount. Please note the word ASSUMING. The block and cylinder heads all have different part numbers after motor no. 4444. I know for a fact that the bore spacing is different between a small bore and big bore engine.
As for your question about cyl. taper I will quote from the 1931 Chilton's Automotive Multi-Guide. Cylinder taper, Desirable .001-.002, serviseable .003, repair or replace .005. Cylinder roundness, desirable .0005-.001, serviceable .002-.003, repair or replace .004.
This is just one opinion for you to take into consideration.
CORDially Mike

Ken,
my engine is the big bore engine which I have been told I cannot bore it oversize as there is not enough wall thickness to handle it and that it has to be sleeved. I have about 0.008 taper in the cylinders and one of them is scared pretty bad from a broken piston ring. So, that being said is it true that the big bores cannot be bored oversized?

Chad
If it all measures out then there is nothing wrong with it, but the cylinder is a different story, if it is worn to much for this piston you will need to bore and sleeve the cylinder back to the correct size for this piston.
My 2 cents
K Clark

Troy,
Shelf wear usually found on the top of the piston. but thanks for the input.

So,
re-usable or buy replacements?

The skirts show slight wear, nothing unusual, just the issue above the top ring.

On most all engines, the area above the top piston ring gets carboned up , especially as the engine wears and burns more oil. I call it normal.
My 2 cents
K Clark

Most likely piston to tight against the cyl wall thus overheating and gauling itself on the cyl wall. Randy

shelf wear? Or, did you use torch to remove?

Slowly working on my L29 engine and notice that the pistons all have what appears to be either scuffing or possibly burning around the upper edge of the piston, above the top ring. Has anyone else noticed this on their rebuilds and if so what do you think was the cause?