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Rod journal diameter

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tdooley
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2019/04/25 21:18:03 (permalink)
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Rod journal diameter

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    tdooley
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    Re: Rod journal diameter 2019/04/25 21:22:28 (permalink)
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    Reading my rod journals should be 1.622 but are 1.605. Ordered new rods they are 1.622 old rods are 1.607 two thousands larger than the crank I’m just going to reuse them. Just wondering why such an odd size. Ideas?
    AVB
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    Re: Rod journal diameter 2019/04/25 22:35:41 (permalink)
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    Looks like you have .020" undersized crank-pin.
    tdooley
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    Re: Rod journal diameter 2019/04/25 23:27:39 (permalink)
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    ya thats what i was thinking but if its 20 under why isnt it 1.602 maybe im just reading the minimum shaft diameter spec. thanks for confirming my initial thought i'm new to small engines always worked the big stuff bit of a learning curve
     
    AVB
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    Re: Rod journal diameter 2019/04/26 08:26:50 (permalink)
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    According to the service manual the standard journal diameter is 1.6235” – 1.6243” (41.23 – 41.25 mm) with a reject of 1.622” (41.20 mm). Briggs did make some  0.020 under journal crankshafts and by using the above figures 1.602" would be the reject size for .020" under crankshafts.
     
    The crank pin journal bearing of the rod standard is 1.625” – 1.6255” (41.27 – 41.28 mm) with a reject of 1.627” (41.32 mm). Of course the oversize bearing will have a .020" smaller diameter. If reading correctly that gives about .0007-.0020 clearance on a standard crank journal. This clearance should be the same for a .020" undersized journal.
     
    From the number posted I say it within spec though the rod bearing is at the max clearance. But I would use plastic gauge to determined the actual clearance as I don't trust my cheap digital caliper to that accurate in the .0001 range as it has a +- one to three digits.
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