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+--- Thread: White Metal Bearings (/showthread.php?tid=7601)
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RE: White Metal Bearings - Dennis Nicholas - 09-06-2022
Just remember that if you file the caps the caps have an oval hole instead of a round hole when re-assembled.
But then if new white metalling was done and properly line bored (i.e. round) would the slight ovalness of the conrod itself matter? (just asking out of curiosity as who knows what was done to our conrods in the past).
This is one for the very clever highly trained professional engineer. (differential expansion of different metal thicknesses of the parts of the filed down caps
Dennis
RE: White Metal Bearings - David Stepney - 09-06-2022
Dennis, I am not sure that the slight amount of ovality in the conrod as a result of filing it would make a ha'peth's worth of difference.
1. The amount of ovality would be measured in a few thousands of an inch and it is not unknown for big ends to 'spread' a bit anyway.
2. When remetalling, the conrods would be checked and ,if required, rebored back to circular before the new metal was run in. The new bearing material would then be bored to suit the crank.
3. If the rods are filed, the resulting bearing would be slightly oval anyway, being wider side to side that top to bottom. It is the top to bottom clearance that is crucial to a quiet big end bearing.
4, The bearings shouldn't run that hot anyway, as they will be cooled by the oil. Seven engines in standard trim tend to rum cool anyway.
RE: White Metal Bearings - Colin Reed - 09-06-2022
Hi All
Modern High Performance Rods are Resized all the time because of stretch to keep them round for fitting Shells because the Tolerances are a lot tighter.
The rod and cap are machined not filed
My Thoughts on this are if you have that much wear to think about filing then you will also have wear on the crank pin
so a rethink is in order if just wishing to keep engine running and not doing alot of hard miles filing caps and scraping is fine
a regrind and remetaling is the long term fix
Colin
NZ