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Ring end gaps too large!

P

PhilSch

Regular Contributor
I have a freshly and accurately bored .040 over 110 horse Johnson block. I purchased .040 over piston/pin/ring set. The Riken rings are stamped 1.0mm which should indicate .040 over but the ring end gaps measure at .030. The ring packages are also labeled correctly. This makes zero sense. Of course I plan to contact the supplier tomorrow but as anyone encountered this before?
 
faztbullet said:
Either bad batch or measuring incorrectly...
Click to expand...

I thought maybe the box of rings were labeled wrong so I measured all eight rings in multiple cylinders. All gaps are .029 to .030. The block was bored to exactly 3.5400 in two holes, the other two are 3.5404 and 3.5403. I know how to measure accurately to the ten thousandth of an inch, have a dial bore gauge and a calibrated mic.

I talked at length to Dan at WSM who is the manager of their marine division. He said the OMC ring gap spec of .007 to .017 was changed years ago to .017 to .031. He said he has taken many calls on this topic and assured me the rings are correct and the motor will run great.

What say you?
 
Yer good....
spec1.PNG
 
Thanks for sending that Pappy, you're the best! I remember back in my drag racing days (Top Fuel Harley) more than once making a mistake grinding too much off the ring ends due to being in a a hurry and never saw a reduction in power. Not exactly apples to apples but the basic concept applies.
 
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