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Engines have not changed much since 1940 - yeah right

So why hone a modern cylinder using 1940's technology? In fact why hone any cylinder with old technology. One of the main reasons for changing is because it makes a better job; in the long term it is also cheaper to operate. However the initial cost prevents most shops from being able to offer this advantage; we had no choice because cylinders plated with nickel/silicon-carbide cannot be honed with anything else. You benefit from this because you get a factory finish on your cylinders.

Many years ago mechanics would bring us cylinder blocks to rebore; they would say "it's not possible to re-ring these modern (1970's) engines" The answer was obvious; their honing was much worse than what we were doing; ours was a far cry from what they did but it was still not as good as a factory finish. Have a look at this; it is the wrong way to hone a cylinder but is ok to remove rust from a drain pipe. http://www.youtube.com/watch?v=fQf17cFziLM. It makes me cringe everytime I watch it.

So what do we need to do to get rings to seal effectively in a cylinder.

1:- Provide a suitable bearing surface for the rings; not too smooth or it won't hold a lubricating film of oil; not too rough or it will wear the rings during running in and hold too much oil leading to high oil consumption.

2:- Provide a cross hatch angle that controls the amount of oil carried to the top of the cylinder; too flat an angle and there will not be enough oil to lubricate the top ring; too steep and the engine will use an excessive amount of oil.

3:- Remove any machining marks and torn material left by the boring bar and a brushed finished to smooth the peaks and valleys creted by the first honing stages.

4:- Produce a round straight bore.

For the technically minded an article by Kolbenschmidt


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