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Big end and main bearing sizes

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Thankyou Colin mate this is what I thought, reason why I asked there's a engine guide on here


And I understand it's for a build a forged but in the built his put

"Next is to put the main caps on to hold the crank in place, these also need bearings put into them, there are 5 of of them and they are numbered 1-5, again cover the outside in oil once fitted.. It is very important you put these on the correct way and in the correct sequence. You will notice that each one has a number on the top and also a small peg in the middle to indicate the direction it should go. Number 1 starts on the clutch/flywheel side with the peg facing the timing belt and then 2,3,4,5 all follow the same pointing towards the timing belt side with those pegs."

If number 1 cap starts on the cambelt side and NOT the flywheel side this is very misleading to people

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  • 1 year later...

Bringing back an old topic here. I didn't realise that you had to be so specific with the tolerances on bearings. I thought it was a case of they're stock, or they're oversized by 0.25mm.

I've just measured my crank with a caliper because it's all I have, and they're around 46.90 on the mains and 39.90 on the biggies so I presume it's standard size.

I'm willing to buy a gauge that goes into the thousands to check them properly, but then when I have a look for replacement bearings, the only options are stock, or .25 oversize lol! Example...


And the oversized, with no specific options


So.... Is it really no use buying the "standard" size bearings listed above because they might be out? Or realistically is that thousand of a mm going to make any difference, and generally a standard size replacement will be fine?

Also is there any real benefit of using an ACL bearing over a standard one?

Cheers guys!

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Colin will know this answer he guided me through mine mate, I put genuine Toyota bearings in mine, don't for get there are 3 different size bearings so yes you do need to get it right first time, I would personally by the gauge what goes into thousands I actually brought one of eBay cost me £50 and only used it to built my engine, I will let colin take over now as he can explain it abit better 👍🏻

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^^^^ why ???? it real simple to measure

aaadzz123 you need a micro meter 0.000 to take measurements as pat mentioned there is many diferent bearings in the last 0 diggit !!! invest in 1 and keep for life

you can buy the acl but there al 4 the same size and not ideal you can chance it and be ok or it could bit u in your ass i never buy acl some are bad fit anyways

anything you wanna know pm

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