Forum

[Norm]

 Problem with the replacement white metal bushes I have seen are either not round, won't fit the crank pin or  if it fits the crank pin it won't fit the rod. Made in India, buyer beware. If they were made in England it might be worth a shot. Having said that yesterday I split a crank that had a Carillo rod and roller in it and the roller was a mess.We don't know how many ks it has done but the current owner has certainly ridden it hard for the few years he has had it. Problem is it needs a new drive shaft and it is not worth putting back together with an Indian drive shaft because the ones I have here all have up to .64mm runout and some of them are new. Not sure what to do

[Norm]

 Here is another thought if the Japs made a floating bush for an Enfield I would certainly give one of those a try

[Chris]

I have fitted 2 white metal bearings in a 1942 WDCO.  I had to fetttle and hone the bearing/fixed con-rod-bush to get the fit.  I think the figures I worked to were 1 thou slack on the crank-pin and 2 thou on the con-rod.  This came from a workshop manual somewhere I think, or it was a best practise thing.

[Chris]

I finally have the big-end bearing out. You can see it at:

http://www.gaz67b.1trewithen.co.uk/bullet.htm

I assumed that the bearing would simply wear and breakdown, but if you look at the picture you can see what appears to be white metal de-laminating or something like that. Is this normal?

[Norm]

Chris, perfectly normal, steel ring, whitemetal coated

[Chris]

This breakdown was slightly confusing because when testing the bearing by squirting oil in throught the crank, the resistance was high AND there was no leakage from the main bearing (causing black smoke on start-up).

[MadMike]

Chris I did tell you some weeks ago to strip the thing. Metal should not be in the oil, as the oil is the life blood of the engine.

The "testing" of oil pressure by squirting into the crankshaft is an entirely pointless exercise which will only serve to build up the muscles in your fingers I am afraid. The resistance you felt was simply caused by the restrictive nature of the oil ways and the viscosity of the oil.

Leakage of oil via the main bearings would not create smoke on starting. In order to generate smoke the oil has to be burnt and that means accessing the combustion chamber, hence it is usually associated with piston ring, bore and top end wear. The smoke if it was oil would be blue. Black smoke would be a clear indication of an over rich mixture on a petrol engine, or injector wear on a diesel. You would not mistake the blue oil smoke for black believe me.

Now that you have bitten the "Bullet" (ha ha pun definitely intended) remember that the metal from the white metal bearings could be anywhere in the engine. A full strip down and thorough clean, including all oil ways, running and bearing surfaces etc is absolutely essential to avoid contaminating th engine after the rebuild. For every piece of white metal that you can see there will be many many more that the naked eye will not see.

[Chris]

Thanks MadMike. The oilways will be getting a good clearing out. Again the thing that surprises me is the way the white metal has de-laminated and cracked. In one place there is a piece that is cracked all the way around, but is still located in the bearing as it was unable to come out.

I understood white-metal would behave more like lead and smear and softly flake.

[MadMike]

Chris white metal when used as a bearing for a simple rotating shaft, like a lathe spindle for instance, may behave as you expected. However in a big end we have the wear caused by the high speed rotational forces coupled with the impacting at the end of each stroke and it is, as I recall, this which causes the break up of the white metal shell.

The signs of metal in the oil normally show before the delaminating and it was for this reason that I recommended that you cease running the engine.

[Norm]

The most important place that whitemetal will be stuck is in the slots in the rocker blocks and if you don't know what you are looking for it is easy to miss, put it back together and bingo,it will strip the pump, and back down the rebuild road again