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72 Posts Member #: 6792 Advanced Member |
12th Dec, 2009 at 08:31:35pm
On 12th Dec, 2009 Sprocket said:
How much 'whip' is considered satisfactory. The crank flexes, I had the pistons touch the head when the bearing failed. The idea amount of crank whip / flex is zero, but this would be in some dream only. The piston could have only kissed the head after the bearing failed. The Crank would have whipped / flexed to this degree again after the bearing failed. I think this is what you have said? Sometimes the reasons for thes failures are quite obscure, but there is always a reason other than the bearing was having a bad day!:) It is highly unlikely - in the extreme - the the bearing was 'bad' to start with since there is (or shouldn't be) bearing-to-crank contact. Looking at your pic, all the white metal was gone and both crank and bearing shell where quite heavily scored. It does not look like debris or the like, however it does have the classic look of 'no oil' hence why I suggest that either the engine was started with first fully priming the system, which I serriously doubt or the oil centrfuged away from the centre main. A further tell tale sign of this is (i recall) also from your pics the big ends on 2 and 3 looked like they had plenty of oil, but suffered from debris which would have come from the failure of the centre main. I think I read somewhere that your crank has been cross drilled. Is this the mains, big ends or both? Has it been fitted with restrictors? Edited by mowog on 12th Dec, 2009. |
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72 Posts Member #: 6792 Advanced Member |
16th Dec, 2009 at 05:43:10pm
Two other things that many be worth checking come to mind;-
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5795 Posts Member #: 80 AFRacing LTD Newbury, Berks |
16th Dec, 2009 at 11:58:15pm
has the engine been balanced as a whole including the damper and trigger?
AlexF |
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