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Discussion Starter · #1 ·
hey im rebuilding my inline 6 250 and im installing the crank main bearings and there is 2 holes in the bearing and neither match up to the hole in the block but there is a narrow slit through the bearing where the hole is visible is this ok or should i find other bearings or can i drill out these ones to match answers would be very appreciated
 

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Vd=0.7854B2S, CR=Vd+Vc/Vc
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273 Posts
One part fits all solution

Like the other poster said its a jobber bearing, it ain't the jobbers motor and the customer ain't gona know any better.
But this is your biuld your money, your final stamp of approval.
To me that bearing looks like cheese, i'd try and find the proper peice not something that covers half the hole. do your mains crossover to any other motors as a alternative?
 

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WFO
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5,030 Posts
thanks if they are new bearings and machined crankshaft do i need to plasigauge them ?
That's a must-do IMHO. Be sure the crank isn't turned while the plastigage is in place. And wipe the bearing and journal off w/a clean dry rag before taking the measurement- oil may tend to soften it if in contact long enough.

Also be sure the bearing caps (crank and rods) go back on the same journal or rod and in the correct orientation. It's always a good idea to rotate the crank after each cap is installed to be sure there's no binding (I'm sure you know all this, but just to be sure...).

And don't forget to check the end float at the thrust bearing.:)

As far as the oil feed hole in the bearing, if it bothered you bad enough you can carefully relieve the back side of the bearing from the location of the feed hole in the block to meet the feed hole in the bearing, or even drill/chamfer the hole in the correct location. There will be only a tiny loss of bearing surface area lost and won't matter a whit as far as durability goes. Just be sure that the bearing shell is not tweaked should you decide to add a hole or rework it/them.
 

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489 Lemans
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2,139 Posts
plastigage

I trust my crank grinder 100%. I never check bearing clearance. I turn the crank by hand and check for oil painting of the crank. If you do not see a thin layer of oil disapate from the crank. If it looks like the oil is being scraped off the crank check to see why. If the crank is too small you can't water it and make it grow.
 

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WFO
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5,030 Posts
In FL I used the same shops (either Miller Machine on Central in Orlando or Revmaster on OWGR in Orlavista) for more than 30 years. Knew the owners of both and the same guy was head of the machine shop at Revmaster for decades. But I would never trust their work blindly! Maybe it's OCD but for me there are just too many circumstances beyond my control to do that.

That said, I never had a problem w/cranks. One set of BBC rods I got back were way out, I was told they "were breaking in a new guy". Not a good excuse at all IMO, but that was their story.
 

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Cobalt;

maybe you're just a bit anal about your assembly technique? :D

(Im kidding - I don't even like plastigauge; I think it can sit around on the shelf too long and degrade, but you have very limited alternatives)
 

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WFO
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Maybe I am.:D But I try to measure the things I can, and after spending what I have on tool$, it would be a shame not to use them for what they were bought for.

I agree plastigage is a mixed blessing but I believe it's better than doing nothing.
 
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