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Old 07-04-2007, 05:52 PM
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Cross drilled mains?

What does this mean, or what are they?

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Old 07-04-2007, 07:10 PM
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i think your talking about splayed main caps meaning that the lower main bolts are not parallel with the upper bolts.

A 2 bolt block is machined (tapped and threaded ) like this /| |\ instead the stock 4 bolt || ||

http://www.gofaststuff.com/graphics/Eagle-CAPS3.jpg

this is supposed to be stronger than a factory 4 bolt block
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Old 07-04-2007, 07:17 PM
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It has to do with drilling an extra oil passage in each main bearing journal in an effort to increase oiling efficiency.
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Old 07-04-2007, 07:29 PM
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sorry for the wrong info, i stand corrected
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Old 07-07-2007, 02:25 PM
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Here's some info on the mod by Jack Merkel Racing Engines.

"David Reher of Reher/Morrison recently reported having experienced rod bearing failures in big block Chevrolet engines with cross drilled crankshafts; replacing those crankshafts with cranks not cross drilled seemed to cure the problem. Here’s the theory: a ½ groove bearing only supplies oil to the rod journal for 180 degrees of rotation, the other 180 degrees residual oil lubricates the rod journal. Cross drilling provides another source for that oil because as one oil hole passes the end of the oil supply groove, the other hole opens up to the groove. But, here’s the problem; in a cross drilled crankshaft, oil has to fight centrifugal force trying to flow to the center of the journal before flowing to the other side where it can feed the rod bearing. If pressure is inadequate to counteract the centrifugal force, oil will actually be forced out of the cross drilled passage and can potentially obstruct oil flow! Oldsmobile big blocks typically have what is referred to as a "fully grooved" main bearing. The oil supply groove runs the full circumference of the bearing. There is really no need to cross drill the crankshaft as the rod bearings have continuous oil flow. Remember, the oil feeding the rod journals from the main bearings do not go through the center of the main journal, these passages are angled toward the rod journal so oil passing through these passages face only a fraction of the centrifugal force that the oil passing through a cross drilled passage would face. Bottom line: in my opinion, don’t cross drill your crankshaft!"
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Old 07-07-2007, 10:21 PM
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Cross Drilling Crankshaft

Cross Drilling your crankshaft will only do nothing but supply your rod bearings with 50% more oil than usuall. This is only going to be needed in full blown "Race" conditionsions. And you will also need a "High Volume" oil pump to keep up with the flow rate demanded by this modification! If you are going to make less than 500hp on the street, don't even think about going to the cost of this modification! Just my opinion, Westfaliaguy!
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Old 07-08-2007, 01:35 PM
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My engine has a cross drilled crank in it. I run a big block pump in a small block. It has 60 psi at hot idle and 80 psi running down the road. Also have the oil by pass plugged in the filter base. This makes all the oil go thru the filter.
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Old 07-08-2007, 06:47 PM
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Cross Drilling Crankshaft

I believe that a big block oil pump on a small block would be considered as the same as using a "High Volume" pump. I think that blocking off the oil pressure by-pass valve is not the best idea. It is there for a purpose. If you block the by-pass the engine could make enough pressure when the engine is cold that you could blow the oil filter apart. I live up here in Canada where we have truly cold weather! 30 PSI at idle and 50 PSI going down the road should be enough to adequately lubricate the engine. To make 80 PSI oil pressure you are lossing some horsepower to drive the pump and over stressing the pump's drive shaft unnecessarily. Just my opinion. Westfaliaguy.
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