Big end bearing markings - size?

[MorrisJohn]

Using advice from an old thread I have removed and checked a big end shell to check its size before ordering new ones.

The markings on it read as follows:

COUNTY
REGD. UK
C617 020 GB

There are no markings anywhere else on it. My guess would be 20 thou from the “020” but I don’t want to order things based on a guess.

Can anyone help me understand what size this is?

Thanks.

[oliver90owner]

Best might be:

First use internal calipers or telescopic gauges to measure pair of shells in a properly torqued con rod, followed by a calibrated micrometer to measure across the above.

Or

Measure the crank journal with a (calibrated) micrometer. Checking for ovality would be good, too.

If you don’t know the history of the engine, check all of them. Also, check the main bearings, while you have it apart.

Some recommend using plastigauge when refitting, to check clearances, but may not give the whole picture if the crank is oval.

I use one of these to measure, but good analogue ones are sufficiently accurate : https://www.arceurotrade.co.uk/Catalogu ... icrometers

[MorrisJohn]

Thank you for the detailed reply. Unfortunately don’t have said gauge, at least not at the moment.

I might have known it wouldn’t be as straightforward as just checking the size of the existing ones

I do know the engine was professionally reconditioned about 5,000 miles ago and all the bearings were replaced at that time. It is unfortunate they need done again.

Best might be:

First use internal calipers or telescopic gauges to measure pair of shells in a properly torqued con rod, followed by a calibrated micrometer to measure across the above.

Or

Measure the crank journal with a (calibrated) micrometer. Checking for ovality would be good, too.

If you don’t know the history of the engine, check all of them. Also, check the main bearings, while you have it apart.

Some recommend using plastigauge when refitting, to check clearances, but may not give the whole picture if the crank is oval.

I use one of these to measure, but good analogue ones are sufficiently accurate : https://www.arceurotrade.co.uk/Catalogu ... icrometers

[philthehill]

Your bearing supplier should be able to determine the size from the info on the shell.
County bearings are not rare so the information should be easy to find.

[MorrisJohn]

Thanks, I’ve confirmed they’re 20 thou oversized.

[philthehill]

Undersized.

[MorrisJohn]

Undersized.

Haha, thanks I’ve found some Vandervell NOS ones in the correct size, I’d be interested to know your opinion on those Phil?

[philthehill]

You will not go wrong with Vandervell bearings.
I use Vandervell bearings in my 1380cc engine and never had a problem with them.

[MorrisJohn]

You will not go wrong with Vandervell bearings.
I use Vandervell bearings in my 1380cc engine and never had a problem with them.

Great, thank you. Very good to hear.