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How bad are scratches in the main bearings seats?

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Hey guys,

The story with the B16A2 engine is too long to tell, but shortly, I got all the parts to rebuild it then realized that the main bearings seats have some scratches.

Some of my friends tell me I need to throw the block away, some tell me that they are too shallow to cause any issue.

Some options I can think of:

- Replace the block

- Ignore the issue and build it as it is

- Polish the seats

- Solder the scratches then rebore the seats

- Use some kind of metal paste then rebore the seats

- ???

What do you think?

Video: https://youtu.be/bnRUKlGj-WM

You CANNOT even think of using it in that condition, period!

You really have only three options -

a/ have the mating faces of the caps skimmed and the crankshaft bores re-honed to size

b/ check if you can have a supplier make a custom set of bearing shells (for some common engines they're available 'off the shelf'), this is a better option as it will keed the centre-line of the bores in the same place. I know KING, for one, offer them for Subarus, and also do a custom bearing service - https://www.kingbearings.com/contact/.

c/ look for another, good, block and start again. I don't know how easy they are to source, though. With the honing, you may need to send the block to another country if you can't find a RELIABLE machine shop to do the work - if unsure, try contacting some of the car blubs and other car enthusiast clubs in your country to see where they get their work done. malto and Italy are just over the water, and I know there are many high output engines built in those countries, so definitely viable options.

TBH, I'll be damned if I have any idea how the bores got damaged like that - especially if it was a running engine.

Thanks Gord.

If I could through the trouble to do b/, I might as well do c/, which would be a pita and expensive as I'll have to source the block from Europe. Also annoying because I already purchased the cylinder sleeves for my block.

Can you explain a/?

And why is that damage so bad and what could happen if I ignore it?

Also FYI that engine had multiple rod bearings failures, they even spun at least once.

GTG for an appointment, but this may help a/ https://www.google.com/search?client=firefox-b-d&q=align+honing+main+bearings#fpstate=ive&vld=cid:53c01f94,vid:qMrIG41wodE,st:0

Bearings don't seat properly and they won't be round in their bore = bearing and crankshaft failure.

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