I'm having some trouble fitting Grant piston rings to my newly overhauled engine. The block is 0.040 over with aluminum pistons. The oil control ring has the spring expander on the inside of the ring itself, and no matter what I do I can't get the ring to compress enough to get the piston into the bore. I can get the piston into the bore if I leave out the oil ring but include the two compression rings. Ring gap on the oil ring is 0.008 on all four. I've tried each piston in each bore and its a no-go no matter what.
I don't understand. Maybe the oil ring groove in the piston is too shallow? Anyone have any ideas? Maybe my cheesy $10 ring compressor is letting me down? It worked fine the last time I had it out, fitting new rings to old cast iron pistons trying to cure the symptoms without fixing the problem.
The pistons are the 0.040 aluminum available from Langs, the rings are the recommended 0.040 Grant set available from the same supplier.
Zack, Measure the O.D. of the oil ring groove. Measure the lip of the expander x 2 plus the compression ring x 2 and see if its to tight. It may be the piston groove. Scott
I just installed a new set of aluminum standard pistons from Langs with Grant rings and everything was perfect. All four of the pistons with pins in them were within one gram of each other. With the oil ring installed push the ring to one side. If the outside of the ring is inside of the piston they will go in the bore. I think you better get a better ring compressor.
You might call Grant but I think you may want to adjust the end gap. A gap of .008" is pretty tight. I don't think it would hurt anything if you shortened either the spring or the wire a bit to get a bit more cle4arance.
For your cheese problem you can always use a worm drive hose clamp near the bottom if it needs a bit more torque.
I purchased a more robust ring compressor and managed to get them installed. Thanks for the suggestions, and sorry for the panic forum post. All is well in Charlotte.
.008" is not enough gap- .012" minimum. Dan
On the oil ring, Dan? I've seen a couple of different opinions that went 0.015 - 0.016 top ring, 0.012 middle, and 0.08 oil control, which is what I went with. Is that not adequate?
(Message edited by zdillinger on October 05, 2015)