Line boring your block, worth it?

[IJ.]

Mik: There's quite a few sizes available but.... and you knew there was a but, once you go to 2nd undersize you're under the Toyota surface hardness and cranks seem to fail quickly.

This is why I went to the expense and frustration of having mine Niterided and re heat treated.

 

[miggles]

"aahhhh thank you for your wisdom master" *in a chinese kungfoo voice*:icon_bigg

When you say failing what does that mean.isit like the crank/bearing gets scored much easier or can it crack/break/warp easier?Im going to think about getting my new crank machined now.If i micropolish it what exactly isit (not just polishing it to a mirror finnish isit?) and will it affect the bearing size in the end?

 

[IJ.]

Usually during a cold start there's some bearing to crank contact until the oil pressure comes up, it's during this time the Crank if it's not hard can scuff which in turn damages the bearing which opens up the clearance making it take longer to get pressure and so on over and over until it gets rod knock!

Micropolishing shouldn't remove any material if don't right it's just using ultrafine abrasive.

 

[Nick M]

Mik: There's quite a few sizes available but.... and you knew there was a but, once you go to 2nd undersize you're under the Toyota surface hardness and cranks seem to fail quickly.

Yep. Toyota says to throw them in the garbage awfully quick.