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How can you read a crankshaft bearing?

I know not to ask random questions, without searching the group first.. I've searched on here about crankshaft bearing sizes, and came up blank.. I can't find anything.

I bought a 1500cc H case to do an experiment on. (let's not mention) ....

I have a few cases, and have had my hands on a few cases..

I've got the recent stroker, an AK, an AH, and this H.

The reason I question this H is because the sensor that connects to the coil, is on the top rather than the side.

I have brand new STD bearings from Silverline, and several old STD bearings. They have all fit my STD un-alignbored cases.. I've never encountered this problem yet.

This H case has got me wondering. I know it might be oversized from align boring?? My STD crankshaft bearings are all loose in it. The main question is that this H case has a bearing in it, fits great!! It says STD too.. can anyone tell me by the number on the bearing in this H case, what the oversize is? It says M 8 03 STD BC 364. or is this just a worn and beat out case?

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Ok with a cheap digital caliper..

The measurement of the bearing surface on my stock case is 64.99mm

On the H case it is 66.47mm

Give or take a few tenths..

I measured on the case half, the highest point on the bearing surface opening.

Does this help any?

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I don't know about the bearing numbers, but keep in mind that the base bearings can have an outer oversize (case align bored) or an inner overize (crankshaft reground). The STD marking may tell you that the crankshaft is not reground. If your measurements are correct, your case is align bored (0.5mm oversize).

Bill Spiliotopoulos, '67 Bug.

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Bill Spiliotopoulos

Ok I came up with a better idea. Rather than trying to measure the case surface, I measured the outer diameter width of the bearings.

My stock bearings were 65mm in diameter. The H bearing in question was 66.5mm in diameter.

Is this .5mm in oversize like your say or is it 1.5mm? Would this be considered the first oversize?

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It's 1.5 mm oversize, the third oversize. (sorry I thought I read 65.5 - 65 = 0.5mm) There exists one more oversize (2.00mm) but... That would explain the serial number on the bearings M 8 03 STD BC 364

03 for 3rd case undersize, STD for crank journal.

Align-boring by itself when done properly doesn't weaken the case. The problem is you cannot find machine shops to do it properly. On the other hand, it's a bad thing to use an old and abused case, for an engine of much higher performance than it was designed for and expect it to last as it would when new on a stock engine. Align boring doesn't make an old case new, just makes it reusable for stock applications. For any performance engine I would prefer to have a new case.

Bill Spiliotopoulos, '67 Bug.

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Bill Spiliotopoulos

Thanks Bill, just what I was looking for.

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