Engine main bearing clearance, need some quick input plox
12-06-2008, 01:13 AM
#12
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i pmed him already, hasnt responded yet
i REALLY dont want to risk ****ing it up, were gonna call the machine shop and ask them how much it would be to skim a thousandth off all of the bearing surfaces
i REALLY dont want to risk ****ing it up, were gonna call the machine shop and ask them how much it would be to skim a thousandth off all of the bearing surfaces
12-06-2008, 07:14 AM
#13
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If you are using an Ms590P main bearing grab a set of MS590HX bearings and use one of each. This will give you an extra .0005 and bring you up to .002. If you are using plastigage to measure do not run it at .015, because you are unable to measure taper and out of round, so where you measure .015, it may close up if the crank is larger in other spots and this is only detectable with a mic and bore gauge. Essentially what I wrote in the pm. As for the rods at .015, thats not my cup of tea either, I would run the mains at .015 before I ran a rod at .015, .002 on the rods no more than .025 with 10w30 oil. Ford is able to run ultra tight clearances because of the manufacturing process, there is little human intervention, thus little room for human error on the machine work side. What bearings are being used on the mains and rods?
12-06-2008, 07:46 AM
#14
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If you ever tear down a factory built engine it isn't uncommon (especially with Ford) to find factory rod bearings with .0001-.1003 on the back side of the bearing. You may find several differant sizes in the same engine. I havent found this in any 4.6's as of yet
12-06-2008, 08:00 AM
#15
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The coatings on a bearing surface are there for a reason. A rod or main bearing isn't just one peice of metal by itself. It has layers of coating on a steel backing. Most often it's the steel backing, Copper/lead and Babbit and sometimes a moly coating. If you did that it would render the bearing useless like it a half a million miles on it already.
12-06-2008, 08:06 AM
#16
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I am sure he is talking about the journals on the crank. You can polish off .0001-.0003 fairly easily, but taking .0005 off with a polisher will almost guarantee inducing taper and out of round. OP what rod and main bearings are being used, thats first off
12-06-2008, 08:08 AM
#17
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The coatings on a bearing surface are there for a reason. A rod or main bearing isn't just one peice of metal by itself. It has layers of coating on a steel backing. Most often it's the steel backing, Copper/lead and Babbit and sometimes a moly coating. If you did that it would render the bearing useless like it a half a million miles on it already.
12-06-2008, 08:12 AM
#18
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Yep I'm old. I'm so old I remember back in the day cutting up my boot to make a leather rod bearing to get home on, lol
12-06-2008, 08:22 AM
#19
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Probably so, But I've seen a lot of stuff in my day, lol
Saw a guy grind the base circle down on his own cam with a bench grinder to increase lift. He filed it smooth and everything. It actually ran for about a half and hour. I was only about 10 years old but it was funny then.
Saw a guy grind the base circle down on his own cam with a bench grinder to increase lift. He filed it smooth and everything. It actually ran for about a half and hour. I was only about 10 years old but it was funny then.
12-08-2008, 02:51 PM
#20
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Been there done that!. Another old guy here, and I always found that the tongue portion of a work boot worked best (after soaking it in oil). I also remember more than once, repairing a spun rod bearing by pulling the pan, sanding the rod journal with plumbers emory cloth, slapping in a new rod bearing, and off we went. Usually it didn't last very long, but occasionally it worked for a while.