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MG MGB GT V8 Factory Originals Technical - Con Rod oddity

I am rebuilding my V8 an noticed that 2 conrods are different from the other 6. They seem to be the same size but have slightly different size flashes (lumps) on the webs. All the pistons are the same.
Are all V8 conrods of the same size interchangeable?
I would have expected that a matched set is needed.
Any comments would be appreciated.
Regards
Dave
D M Tetlow

If it were me, I would take the set into a good machine shop to be measured up and if they in fact turn out to be identical length have them do a balance job on the entire rotating assembly. Last ting you want is a couple rods that weigh markedly different than the rest..
Larry Embrey

I have just weighed the pistons/rods and they all vary by about 4 grams in 1170.(0.3%)
All rods have the same 14 digit casting number except 1, which ends 46 rather than 47!! The one with the odd number is one of the similar ones!!
It would seem that if these tolerances are OK for the identical rods then the different ones with the same weight can't be too critical.
The engine has been running with these rods for over 4 years.
I believe the difference in profiles is very close to the big end so would only have a marginal effect on the loading even at 85 revs per sec.
Please correct me if you think I am wrong as I do not want to strip the engine again.
Regards
Dave
D M Tetlow

Well, at that speed, I would want them within a gram. But,
it could be that the weight is there for balance from the factory. Not probable, but it could be factory internal balancing. I've seen some interesting things come out of the English factories over the years.

Kelly
Kelly Combes

This thread was discussed between 03/10/2006 and 04/10/2006

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