mgb b series 1.8 con rod orientation

mgb b series 1.8 con rod orientation

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muso58

Original Poster:

10 posts

19 months

Friday 30th September 2022
quotequote all
Hi
Thought i would start a new topic as my original one is more related to my carb (probably) woes !
I have stripped out the pistons on my roadster .
I found no2 con rod was opposite way round to the other 3 .Obviously a past slip up .
Does anyone know if it matters?
I spoke to a local engineering company that do a lot of hi end mini engine mods ,He said it isnt a problem on A series (mini engines)
He wasnt sure about B series (1.8 engines)
It means the con rod lube jet is on opposite side .
When i mentioned , that i thought it would be important to apply oil to thrust side of piston (i dont know which side that is either!)
He said no, jet is only to serve piston crown area .
Any info on this out there ?
Cheers guys

ingenieur

4,097 posts

181 months

Friday 30th September 2022
quotequote all
The issue is going to be the fitment of the crankshaft. If it was set up at the factory with the bearings and the crankshaft in a particular orientation and one rod was inadvertently swivelled around it could be biting badly on the edge of a bearing. This is assuming in every other respect the rod is symmetrical which they usually are. You can check it by installing the crankshaft with just the odd rod connected and the others out of the block. Turn the crank and see if there's any resistance. Then do the same with the piston installed. Obviously any dragging or grinding is a big issue but if it's smooth and has been running okay then there's no problem. If you want to reverse it so they're all the same then do the same tests.

muso58

Original Poster:

10 posts

19 months

Friday 30th September 2022
quotequote all
Hi
The car is 40 yes old and has had lots of engine work According to extensive history.
Last work resulted in this mistake I think .