Big End Shells - G12

[moley]

I have just purchased some shells from the club and they seem to differ slightly from the ones what were in my 1962 engine?

The ones from the engine had approx 1/8 wide slot (not very deep) in the middle of the shell ( this is a machining and not wear).. the club ones have not got this and have got a hole right through the shell in the middle whereas the ones with the grove hadn't.

i assume this channell was for the oil? - does the hole do the same job?

Thanks

Andy[:)]

[Eric]

Andrew as no one has been prepared to stick their neck out with an answer for you; this is just my educated guess for the difference between the shells you are comparing. At least this may promote someone else to come up with another suggestion. Whilst it is possible the groove in the existing bearing was put there to assist oil distribution, I doubt this was the main or only reason. This is because upon cold start-up with the recommended monograde oil and everything the way it was intended to be, the oil pressure would normally be in excess of 200 psi. At this sort of pressure the oil will get everywhere it is supposed to be, without the assistance of a groove. My guess is that it was put there to act a sort of particle trap, so that if something quite big, bigger than the size of a knats bol????? was pumped into the bearing, it would stay in the groove, rather than be forced into the clearance space between the shell and the journal. Once upon a time in engineering they once used what they thought was the best solution to a problem, despite the cost. Now they use the most cost effective solution, so the hole you describe will still trap the big knats bol????? after its moved round the bearing a little way, but it cant trap as many of them as the original groove would have done. If however you were using a proper filter as I have discussed elsewhere, there would not really be any big knats bol????? getting there in the first place, which maybe why today’s bearing manufacturers only have the facility to include a hole and not a groove, as this would not be used in any other bearing shells for general original, or replacement use. Hope this helps. [:)] [:)] [:)][^]

[bjork]

No No No! he's wrong you know, that type of bols was withdrawn when it became obvious the fruit flavours would have a wider acceptance with the drinking public. As a certificated supermarket inspector Eric, you really should have been aware of that[;)]