Conrod big end bearing sizes

[Andy Ven]

Evening guys,

 

Now i know i have read a very informative post about this before but i cant for the life of me find it. It says about sizes and markings on the crank and rods.

 

I have however measured wverything on my engine.

 

Every rod diameter on the crank is 51.98mm

 

Big end rod size ranges from 55.05 to 55.07

 

They are all however marked up with ‘37’ ground into the rods.

 

The bearing which are cureently in measure 1.5mm thickness exactly. Which would give me around 0.07-0.09 clearence. Basically 3-4thou. This is a stock engine and shells have not spun.

 

Anyone help with new bearing sizes? And explain the 4 thou clearance currently? Ps current bearings show zero signs of wear.

 

Cheers in advance

 

 

 

 

[Swampy442]

Its the UK not the US, nobody has used 'thou' for 40 years lol The crank and bearings will be marked with their standard sizes.

 

[Andy Ven]

Haha, its usually referred to as old english [emoji23] i use a mixture of both as i have use of an imperial milling machine, and sometimes thou is easier. Specially when doing valve shim clearances. Smaller numbers [emoji23] i will have another detailed look tomorrow. Acl only seem to sell shells in standard. 1 thou bigger or 10 thou bigger. 0.025mm or 0.25mm for you new english they dont seem to have as many size versions as toyota do

 

 

 

[Andy Ven]

My current shells also have a 5 digit code on them. Its a mixture of numbers and letters. But that doesn’t correspond with what that drawing says. As it says 1 number :/

 

 

 

[Andy Ven]

So... heres the pics.

 

The crank numbers im happy with are self explainatory.. but the conrod and shells... not so.

 

 

 

 

 

[Mike2JZ]

What kind of measurements do you get for oil clearance on the rod bearings if you use plastigauge? Not doubting your measuring skills, but just to sanity check. 0.07-0.09mm oil clearance as you have calculated is beyond the max for rod bearings. Should be between 0.023 to 0.041mm range for a STD bearing set

Edited July 14, 2019 by Mike2JZ (see edit history)

[Andy Ven]

What kind of measurements do you get for oil clearance on the rod bearings if you use plastigauge? Not doubting your measuring skills, but just to sanity check. 0.07-0.09mm oil clearance as you have calculated is beyond the max for rod bearings. Should be between 0.023 to 0.041mm range for a STD bearing set

 

 

 

Hey mike, i got my dad who has been a machinist for over 30 years to double check my measurements, and they came back exactly the same. I dont have a plastigauge set so cant do that test. The only thing i have done is look closely in the manual at what sizes pieces should be (according to what they are stamped). My crank is stamped 111010.

 

0 is 51.994-52.000

 

1 is 51.988-51.994

 

All measurements i took using a set of freshly calibrated and good make (moore and wright) micrometers. Mine came back at 51.998 across all. So i am unsure of how my measurements have got bigger compared with when it was made. Micrometers are calibrated at 50mm exactly (using a 50-75mm set).

 

All the con-rods are marked 3.

 

3 is 55.037-55.043

 

My measurments range from

 

55.04-55.07

 

Even with the shells as they are. The oil gap is too much. from the numbers and letters on them. I am still non the wiser on how to identify them.

 

The manual does say.. maximum standard oil gap is 0.07 so this is allowed?

 

I was going to get acl rod bearings but im not sure they do them in the sizes like oem toyota do?

 

 

 

 

 

 

 

[Andy Ven]

So as an update, i have been in touch with ACL. I gave them my specified sizes off using the numbers stamped on the rods and on the crank. They recommended the 0.025 shells to give me the correct clearance, not the standard ones.

 

I have also decided to replace the main shells and have given them the specs of my crank and main sizes. Just awaiting an email back from them on that one. My main shells were quite worn. Especially the one at the damper end of the crank (shell 1).

 

I have purchased Acl’s plastigauge set so will be testing the clearances to see how accurate my measurements were. (Considering how far out some of my measurements seemed to be).