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Author Topic: Big end  (Read 220 times)

vegoil

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Big end
« on: October 03, 2018, 11:48:29 PM »
I am having to renew the Big end shells on my Lister CS 8/1 because of a knock I put a length of thin soft solder all the way round the crankpin nipped up tight this measured 7 thousand all the way round this would be 14 thousand of slap! wouldn't it?
The worn crankpin measures 2.496850 at one side and 2.496063 at the other. it doesn't seem to be oval.
Do you think that this size would be permissible?

broncodriver99

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Re: Big end
« Reply #1 on: October 04, 2018, 12:15:13 AM »
According to the spec sheet I have and if I am interpreting it correctly Lister lists the crank pin at a nominal 2.5" diameter with machining limits of -.002" min and -.0025" max. I believe these are the specifications for a new crankshaft. So one would have left the factory with a finished diameter of 2.4975-2.498". Lister also lists a maximum allowable wear limit of .007" on the big end.

You appear to have .0007" of wear on one side and .0015" on the other. If I am understanding the Lister specifications correctly you are well within the acceptable range for a standard size big end bearing.

I would try a standard bearing and get some plastigauge to measure the clearance. Soft solder is likely as hard or harder than the babbit material on the big end bearing shell which could cause damage to the shell and likely give a false reading as it may be dimpling the shell.

vegoil

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Re: Big end
« Reply #2 on: October 04, 2018, 07:40:01 AM »
Tanks for the reply.
I will order new shells from stationary engine supplies but I think they are closed until next Monday.

38ac

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Re: Big end
« Reply #3 on: October 04, 2018, 12:31:04 PM »
Reprogram that electronic mic to get rid of the .000000 or pay no attention to anything past .000 and round it to closest 5 tenths, you made my head spin,  :laugh: LOL'

As Bronco said your crank is within spec to go back into service  Install the cap on the rod and tighten the nuts. Measure the ID next to the parting line and 90 degrees to it.  Should be within .001 of being round, if not then the rod needs resized and likely due to having the solder clamped under it, it doesn't take much to spring the cap.  When your shells arrive check the clearance with plastigauge which is available on every country's Ebay if your automobile supply house doesnt have it.  If everything is right you should have just over .003 clearance with that crank pin measurement  which is fine.



Collector and horder of about anything diesel