psimitar
2014-12-31T09:27:54Z
Hi there,

I'm wondering if any engine guru's can help me out here. I've rebuilt a good few engines in the past but they've all needed crank regrinds and popped the new bearings in with no dramas.

However, on my first 30hp Oval engine I measured the journals as within tolerance and ordered the STD size bearings from Wolfsburg West, as seemed the main supplier for these old engines.

Anyhow, upon receiving the new bearings I popped no.3 and 4 bearings on the crank and found they had more wobble than the worn bearings so got the feeler gauges out and measure 0.05mm for the worn and 0.08mm for the new bearings. Now reading the workshop manual it says 0.04-0.18mm as the bearing to journal clearance but after searching the interweb I can't find anywhere that states if that is the overall clearance for 2 points directly opposite each other on the journal or is the clearance allowed each side of the journal? So overall would be twice the clearance in the manual.

I'm thinking it's overall as Plasti-gauge would only show the overall clearance but if someone could confirm that'd be great :)

Then I can see what Wolfsburg have to say about their bearings.

Cheers
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mrmagyar
2015-01-15T17:34:20Z
Hi,

Do you mean the con rod side clearance? That should measure in total 0,17 - 0,395mm with a maximum wear limit of 0,7mm.

Cheers,
Andy.
1949 Belgian Standard
1955 UK RHD De Luxe
psimitar
2015-01-20T06:34:24Z
Originally Posted by: mrmagyar 

Hi,

Do you mean the con rod side clearance? That should measure in total 0,17 - 0,395mm with a maximum wear limit of 0,7mm.

Cheers,
Andy.



That's good to know as I need to check that too. For measuring this the rod should be perfectly perpendicular to the crank journal? And not as if you are rocking the con rod by the small end as this would make the measurement larger than it should be, correct?

However, my initial question was regarding the main bearing clearance and someone on VZi answered that one for me. The radial bearing clearance is the clearance on one side of the journal with the other side, 180 deg opposite, tight against the bearing ID.

So either way the new bearings from Wolfsburg have more clearance than the worn bearings so need to get in touch with them to figure that one out.

Cheers,
Mike