Big End Bearings

[Chris Edgar]

I decided to replace the B/E bearings on the Convertible (1275cc)
Took them off last Wednesday to see what size they were & what condition....010 oversize & showing some signs of wear.
So I ordered replacements from ESM, quoted as fitting 948, 1098 & 1275 cc engines at 010 oversize.

What with postal backlog, bank holidays etc., they eventually arrived today only for me to discover that the replacements are smaller than the originals, about 5 mm shorter & clearly a smaller radius. Job off!

So what is going on here? Could this not be an A engine, but an A+ ?
What B/E bearings do I need?

I can't get advice from ESM today as they are shut for the holiday.
The car has been sitting for nearly a week in the garage & is needed. This is only one of the problems encountered with a car which has been previously modified.

Any help & advice greatly appreciated please!

Chris

[Chris Edgar]

Measured the journals using a digital caliper, which will not be super accurate, but the size is:
1.740 inches approx

This tallies with the Marina manual which gives 1.7497 to 1.7504 " ie they are 10 thou undersize from 1.7504.
Bearing shells are 10 thou bigger.

Looking at the manual for the Minor 1098 cc engine, the sizes are shown as 1.6254 to 1.6259 " dia.
Quite a difference to my 1275 Marina engine.

This leaves me wondering why ESM seem to say that the B/E bearing sizes are the same for 998, 1098 & 1275 engines.

Or am I missing something here?

[les]

Are they perhaps saying they stock bearings for all those engines rather than they are all the same?

[mike.perry]

BMC Minor workshop manual lists the following sizes (approx).
803 = 1.438
948 = 1.625
1098 = 1.625
Haynes Midget workshop manual lists
948 = 1.625 (approx), inc. 1098, 1275
BMC Mini workshop manual lists
848 = 1.625, inc 970, 997, 998, 1275

[bmcecosse]

As you have discovered - the 1275 Marina/Ital engines have the lager diameter big ends. Spridget (and Cooper S) engines have the smaller dia big ends. So indeed the shells they have supplied will fit some 1275 engines.......
And errr - the 1098 engine most certainly does NOT have 1.750 big ends............ 1.625 like the rest.

[Chris Edgar]

Many thanks for the feedback, Folks.
Much appreciated.

I will of course phone ESM in the morning. Hopefully they will have the 1.750 +.010 shells. I can return the small ones.
If not then I'll need to cast about, but surely they shouldn't be rare?

There are some listed on Ebay at the mo'. I just need to confirm that they are for the 1.750 crankshaft.


Chris

[Chris Edgar]

The chap I spoke to at ESM was not aware that there were 2 sizes of journals for the 1275cc.

After several phone calls to the usual suppliers I was put onto a firm called FW Thornton at Shrewsbury. The man there seems to know his stuff & has the parts. I have ordered Special D for tomorrow , so fingers crossed.
They look like a good company.

Chris

[bmcecosse]

" ESM was not aware that there were 2 sizes of journals for the 1275cc. " Good grief...........and they are supposedly 'experts'........ There are FAR MORE large size big end 1275 s out there than small size........

[moggyadventurer]

Hi,

I must admit had been down this route myself some years ago, and yes fw thornton at shrewsbury saved the day - a wealth of knowledge but can be expensive.

[bmcecosse]

You will get the correct shells from any of the Mini places - or on ebay ! Often very in-expensively!

[minor_hickup]

" ESM was not aware that there were 2 sizes of journals for the 1275cc. " Good grief...........and they are supposedly 'experts'........ There are FAR MORE large size big end 1275 s out there than small size........

http://morrisminorspares.co.uk/shop/pro ... bbb45ecaf5

[bmcecosse]

Have they added in the caveat about the marina recently ?

[Chris Edgar]

I think that they must have...clearly I did not see that when I was ordering.

[mike.perry]

And errr - the 1098 engine most certainly does NOT have 1.750 big ends............ 1.625 like the rest.

Sorry, my mistake, posting corrected