Bearing Clearences

[Jono]

Evening all,

Please can someone tell me what the bearing clearences should be on the big and main bearings. I cant see it in the Haynes manual.

ta

[Andrew Cooke]

all I have are the journal diameters

main - 54.795 +/-0.01
BE - 43.98 -0.02

[Jono]

Hi,

I have had the crank re-ground by 0.5mm and fitted oversized shells. I was going to use plastiguage to check the clearences. Is their a generic acceptable tolerance. I googled it and it seems to vary from engine to engine.

Do people check this or should i just trust the machine shop and put it together!?

[youngscottie]

check what the machine shop have done with a micrometer:coffee:
a wise old man once told me to aim for about 2thous running clearence and its never let me down

forget plastigauge the sun newspaper works just aswell;)

[olidaviesuk]

As above - use a micrometer to check the grind on the journels, plastigauge is always handy to check that the shells are what they say they are. Have you put in new thrust washers, as they are a must! (especially if you are using an uprated clutch)...

Check the endfloat with a DTI gauge, you'll be surprised how much they do wear!

[bye_all_c_ya]

check what the machine shop have done with a micrometer:coffee:
a wise old man once told me to aim for about 2thous running clearence and its never let me down

forget plastigauge the sun newspaper works just aswell;)

was told that only 4 weeks ago but was told to use plastigauge lol

[Big Jim]

Tolerances are suprisingly big 1-3 thou ends and 1-3.5 thou mains. As the man said, 2 thou is a good clearance to aim at especially on ends. I like to see mains a little looser though, more like 3, especially if you're going to spin it!

[Jono]

I take it 3 thou is still lose enough for it to make decent oil pressure? oil loss from a bearing is squared when the running clearence is doubled.

My last rebuild lunched its mains because I ran it with a duff oil pump and didnt realise it wasnt making much oil pressure. ( Now have a proper guage!) oddly the big ends and big end shells survived totally unscathed.

So whilst the oil pump was to blamb last time im keen to ensure that i get everything spot on so it can make good pressure.