Mercury KG7 Crankshaft, Cylinder Bore, Piston Skirt measurements???

[Tracy Maxwell]

Hello,

Does anyone have the original measurements for a 1950 KG7 Crankshaft:

Upper journal, center journal, lower journal (the KE7, KF7, and KG4 all used the same crankshaft part # 402-48)

Also the original piston skirt measurement: part # 718-1193A2

The cylinder bore measurement is 2 and 7/16 or 2.4375 but what is the thickness of the hard chrome liner?

Finally, what machinists or crankshaft or hard chrome repair shops do you guys use for this?
Is it cheaper to CNC or cast some of these parts?

Many thanks!
Tracy

[A. Hoskins]

Hard chrome liner ?? There is none.  Piston diameters are measured at the wrist pin and you might be able to find oversize ones. Good luck, racers gobbled them up years ago. Typically the cranks don’t wear. Rod journals might gall due to long term storage or moisture intrusion where the needles rust. Even if you refinish a crank how are you gonna figure how many needles to put back in ? Forget it, find another crank. As you know, many models used the same one. If you refurbish a crank, use only 320 grit crocus cloth. The rod journals must have some “tooth” so the needles will roll. Needles will slide on a micro-polished journal and then you lose the crank.

 

 

Certified JB weld

[green-thumbs]

If memory serves, Mercury service Manual stated measurements were not released so mechanics were advised to check suspect crankshaft against a new crankshaft, I believe wear over 0.001″on any journal or roughness that caught a fingernail meant the crank was not good enough for a shop to reuse,  Cost effective way to deal with worn or damaged parts is a good used replacement, Save the reject partsas and tag them for identification and issues,

Just my oar stiring up the water

Louis

 

 

[Tracy Maxwell]

Thank you both!  I assumed incorrectly that because the piston rings were cast iron that the liner was hard chrome.
Appreciate the insight

[Author]

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