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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,120
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The O.S. I am talking about is the out side thickness of the main BNG as it need to be larger after a line bore
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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02-11-2008, 07:58 AM
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Registered
Join Date: May 2004
Location: Boulder, Colorado
Posts: 7,275
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Afterburn
The high cost of oversize (OD) main bearings is what inclines folks to spend extra money on case work where the bearing holes are oval or otherwise pounded. That involves machining one or both case faces a little, bolting it back together, and then liine boring everything back to standard. So you can use standard OD bearings again. It does get confusing, though. An oversize bearing refers to the OD of the bearing. And an undersize bearing always refers to one which is thicker toward the inside and thus has a smaller ID (to go along with crank journals ground smaller). So you can buy a 1st over/1st under to accomodate your line bored case and ground crank. Bring a bag of money, though. Whatever anyone does, don't let the machine shop line bore a case for an oversized #8 bearing. Talk about cost! The case ought to be OK where that bearing is, as it doesn't take the kind of beating the others do since it is not adjacent to a rod throw. Walt Fricke |
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02-11-2008, 05:47 PM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,120
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All I can say is from EXp., do not be shocked if it comes to that..BTDT
I under stand O/S U/S I just get my merds wicked up LOL
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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02-12-2008, 09:04 AM
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Registered
Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,488
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just because the head studs didn't pull means nothing. they all MUST be repaired with case savers on a 2.7 or they will probably pull later on. the 8mm case studs along the I/shaft/oil pump line should all be timeserted . the cylinder bases on the case need to be machined as they are worn and not all on the same plane anymore. the crank will not turn in the case with new main bearings, so the case needs to be properly machined with either an align bore for oversize main bearings or case halves faced and rebored to standard. 2.7s are nice engines if properly rebuilt.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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02-12-2008, 09:57 AM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,120
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Like Jn says it would be a false economy to try to save $$ at this pt. as you are already there
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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02-12-2008, 05:08 PM
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Registered
Join Date: Dec 2007
Posts: 65
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John, thanks for the heads up about the case savers and time serts. Before the motor was taken in it was already scheduled for the case savers in the head bolts, however I did not know about the timecerts along the intermediate shaft. Does this area see a lot of thermal expansion?
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02-12-2008, 07:39 PM
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Join Date: Dec 2007
Posts: 65
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I called the builder today and in that area he prefers a helicoil as it dos not remove as much material when it is drilled out. Anway he is going to get it taken care of. Iguess there is just one long bolt.
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02-13-2008, 07:30 PM
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