Race Engine Forum UK

Hello Guy,

Can you please explain the significance of the sizing stamps in the lower edge of the block. Looking at a manual I have suggests they are a reference to a measured size that determines the choice of bearings used in that particular bore. Are these different bearing sizes an orderable product or established by measuring of a selection of bearings?

Does the crush on the bearing vary with these sizes? The measurments in the manual only refer to I/D. Would there be a preference for choosing a block with smaller sizes if a selection was available?

Do you have a prefered manufacturer for bearings? What preparation do you give them before installation?

Thanks,

Nik

Those stamped codes A-E are nothing to do with bearings, see:

http://guy-croft.com/viewtopic.php?f=3&t=254


GC

Guy,

Of course, my mistake, I have read that before just didn't recall.

The section of the manual I have been refering to states the vaious sizes of main bore tolerances in a similar manner. The various sizes are mirrored by bearings of suitable sizes. Are these available?

Thanks,

Nik

Yes, as an almost global rule crank journals can be reground to 0.010", 0.020" and 0.020" undersize and bearings are available to suit, but whether this is advisable practice depends on the individual crank and you must refere to an OE manual to check first. And in the case of the 2 liter Fiat type crank it must NEVER be reground (source OE manual) because the nitrocarburised layer is just too thin; even the front and rear seals can penetrate it. You must source a replacement crank if yours is worn much below bottom limit.

It is a hopeless exercise trying to grind and re-heat treat, I've tried without success, problem is micro-cracking.

GC

Ahhh, I have a brand new crank so should be OK. It isn't the crank journals I'm looking at.

My Lancia manual refers to main bores in three sizes, increments of 0.006mm according to what I'm looking at. My understanding is there are bearings in 0.006mm increments to facilitate exact assembly. Is this the case?

I'd be keen to know what manufacturer of bearing you prefer?

Nik