7 replies to this topic

[sambrown1992]

I got a 998 block took main Bering out with the number 12g3468 can anyone tell me if they are standard or over size looked on mini sports am mini spares thx

[Cooperman]

If they are for a re-ground cfank they will have the undersize of the crank stamped on the, e.g.: 020. That number, added to the basic bearing part number is the full bearing part number. Without a suffix number the bearings are standard size, but it is vital to measure the crankshaft diameter with either a micrometer screw gauge of a vernier calliper.

[sambrown1992]

Thank I have mesured the crank its 44 mm but can't see it stamped anywhere

[Sfuller1275gt]

Normally stamped on back of the old bearings 010 020 etc.

[Cooperman]

You need to measure it in inches to the nearest 0.001"
If the bearings have no undersize marked then they will be standard size. However, a standard 998 is 1.750" diameter on the mains, which is not 44 mm, it is exactly 44.45 mm.
With engines accurate measuring is absolutely vital.

[sambrown1992]

That's exactly what I wanted to know thank you is there a chart or something witch I can use in the future

[Cooperman]

You don't need a chart.
The crankshaft journal diameters are as follows:

Mini 850, 997 Cooper, 998 Cooper, 1098 Mini: Main bearing journal diameter 1.750", Big end journal diameter 1.625"

Austin/Morris Cooper 'S' 970, 1071 and 1275: Main bearing journal diameter 2.000", Big end journal diameter 1.625"

All other 1275 engines, A and A+: Main bearing journal diameter 2.000", Big end journal diameter 1.750"

Those are all nominal standards sizes and for accurate manufacturing sizes which show tolerances reference needs to be made to the BMC/BLMC/Austin-Rover Workshop Manuals.

Re-grinding is now normally in incremants of 0.010" undersize on diameter and the bearing shells will always have the crank undersize stamped on them next to the bearing shell part number..

[sambrown1992]

Thank you so much