2 STROKE WORLD .net

The 2-Stroke Garage => Turning Wrenches => Topic started by: Arrow on October 13, 2020, 10:27:58 AM

Title: Looks can be deceiving.
Post by: Arrow on October 13, 2020, 10:27:58 AM
On one of these oil pump camshafts the cams are worn out of spec. Which one, A or B?(https://uploads.tapatalk-cdn.com/20201013/ccdeb39e1901dd09dfc7fd9c8eaa6577.jpg)

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Title: Re: Looks can be deceiving.
Post by: m in sc on October 13, 2020, 10:32:19 AM
B, the top looks flatter.

hard to tell at that angle though.
Title: Re: Looks can be deceiving.
Post by: Czakky on October 13, 2020, 12:22:14 PM
I agree, B
Title: Re: Looks can be deceiving.
Post by: Arrow on October 13, 2020, 01:03:18 PM
It is B, although the tops of the cams are supposed to be flat. They normally wear rounded.

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Title: Re: Looks can be deceiving.
Post by: Greaser Greg on October 13, 2020, 11:20:31 PM
Will shimming correct the wear, or is it to the scrap bin for it?
Title: Re: Looks can be deceiving.
Post by: Arrow on October 14, 2020, 05:38:44 AM
Quote from: Greaser Greg on October 13, 2020, 11:20:31 PM
Will shimming correct the wear, or is it to the scrap bin for it?
Here's the long answer to that!
Technically as its right at the bottom of the wear spec. its ok to use. It can be shimmed to give the correct minimum stroke and provide enough oil at full bore (just). However, as there is no more wear tolerance left on it I would not use it in a pump given that I always provide a twenty year guarantee. Its quite possible that it won't be in spec. anymore after a year or two.
We also have to factor in overbore sizes bigger than factory standard, which if present would mean its out of spec. already.

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Title: Re: Looks can be deceiving.
Post by: Alain2 on October 14, 2020, 08:17:56 AM
I found this pump in my stash, I would assume it was ran dry for a while.
Title: Re: Looks can be deceiving.
Post by: Arrow on October 14, 2020, 08:47:35 AM
Not sure whats happened there, looks like corrosion damage first, then mechanical damage later. The cams don't run in oil in any case. They run in grease, but there is never much remaining, some 30~40 years (or more) after they were first built.

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