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RE: +.0010 bearings?
By Frank Hager - 03/04/2003 11:51:14 PM; IP 68.115.254.47
James,

You have me completely confused?

On a standard size crank a +.001 (one thousandths oversize) bearing increases oil clearence.

Whereas a -.001 (one thousandths undersize) bearing decreases oil clearence. This is perhaps the way you need to go to stop excessive oil volume to the leaking seal.

I doubt you have +.0020 (two thousandths oversize, or as you have written, twenty ten thousandths) bearing.

If your crank has been turned undersize you probably have a -.020 (twenty thousandths) under size bearing. If that's the case, you're stuck, because I've never heard or a -.021 (twenty one thousandths) undersize bearing.

If you have a standard size crank it is not uncommon to install a mixture of bearings to obtain the desired clearance. For example, if with a standard upper and lower shell your clearance is .003 and you want .025, it's OK to install one bearing shell from a -.001 bearing set to reduce the oil clearance to .025.

It's no problem to replace the upper bearing shell. Back off all the main bearing bolts to let the crank drop a little. Roll the upper shell out, and roll a new upper shell in. Retorque all the main bolts and you're in business.

Just remember, after a crank is turned you install undersize(-) bearings. Unlike when cylinders are bored out. Here you use oversize(ie.+.030, +.060) pistons and rings.

Also, make sure you install the seal with the lip in the correct direction.

One other thing. I've been told reverse rotation marine engine cranks have different oil seal mechanics than normal rotation engines.
This thread, so far...
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Collapse <a href=../ForumFE/reply.aspx?ID=16376&Reply=16376><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor16376" onclick="return false;">390 -rear main seal replacement</a>&nbsp;-- <font color=#0000ff>James, <i>02/23/2003</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=16376', contentMargin: 60, icon: $('anchor16376') }); </script>  390 -rear main seal replacement -- James, 02/23/2003
Collapse <a href=../ForumFE/reply.aspx?ID=16380&Reply=16376><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor16380" onclick="return false;">RE: 390 -rear main seal replacement</a>&nbsp;-- <font color=#0000ff>John, <i>02/23/2003</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=16380', contentMargin: 60, icon: $('anchor16380') }); </script>  RE: 390 -rear main seal replacement -- John, 02/23/2003
 390 rear seal -- dewey, 03/13/2003
 RE: 390 -rear main seal replacement -- Bruce Geister, 02/25/2003
Collapse <a href=../ForumFE/reply.aspx?ID=16410&Reply=16376><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor16410" onclick="return false;">I agree that it's likely an oil plug...</a>&nbsp;-- <font color=#0000ff>Dave Shoe, <i>02/26/2003</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=16410', contentMargin: 60, icon: $('anchor16410') }); </script>  I agree that it's likely an oil plug... -- Dave Shoe, 02/26/2003
 thanks folks -- James, 02/26/2003
Collapse <a href=../ForumFE/reply.aspx?ID=16415&Reply=16376><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor16415" onclick="return false;">Back of intake</a>&nbsp;-- <font color=#0000ff>Terry, <i>02/26/2003</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=16415', contentMargin: 60, icon: $('anchor16415') }); </script>  Back of intake -- Terry, 02/26/2003
Collapse <a href=../ForumFE/reply.aspx?ID=16444&Reply=16376><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor16444" onclick="return false;">RE: Back of intake</a>&nbsp;-- <font color=#0000ff>Frank Hager, <i>03/03/2003</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=16444', contentMargin: 60, icon: $('anchor16444') }); </script>  RE: Back of intake -- Frank Hager, 03/03/2003
Collapse <a href=../ForumFE/reply.aspx?ID=16446&Reply=16376><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor16446" onclick="return false;">+.0010 bearings?</a>&nbsp;-- <font color=#0000ff>James, <i>03/04/2003</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=16446', contentMargin: 60, icon: $('anchor16446') }); </script>  +.0010 bearings? -- James, 03/04/2003
 RE: +.0010 bearings? -- James, 03/04/2003
RE: +.0010 bearings? -- Frank Hager, 03/04/2003
 RE: 390 -rear main seal replacement -- Dewey, 03/13/2003
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