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robertcosta

Are these cylinder liners too worn

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Advice please, rebuilding a 907 block and just measured the original cast iron liners as generally spot for the new Omega pistons at 95.3 on in the gudgeon pin axis but 95.33 - 95.34 at 90 degrees. Are they too out of round and too much clearance?

 

Rob

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Piston/liner clearance for the 907 engines is 0.11-0.13mm but maybe Omega piston are HC so they need to go with HC clearance that is much smaller.

 

G.

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Hi Giorgio...

The pistons are stamped with "cylinder bore 95.3mm" on them so if the liners measure that, at least in one direction then I hope they are correct for the direction...the other direction however!! 

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What are you measuring with?

 

Buddsy

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Pistons can have different sizes at 90degs (at least better quality ones will) to allow for differing expansion rates depending on where the alloy mass is. Measure the bore wear at 90deg to the crank halfway down the cylinder and work things out from there.

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What are you measuring with?

 

Buddsy

A cylinder bore gauge...

Pistons can have different sizes at 90degs (at least better quality ones will) to allow for differing expansion rates depending on where the alloy mass is. Measure the bore wear at 90deg to the crank halfway down the cylinder and work things out from there.

Hi Danny,

 

95.33- 95.34mm

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I think 0.04mm would be fine. The rings would take that up. In old money its olny just over a thou.

 

Buddsy

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I misread your op and thought you were measuring the pistons. Agree with Buddsy and that slight amount of wear is ok. Run a flexihone down the bore and it should be good for another 100k's.

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What you DON'T want is for it to be too tight......that's really bad news; there you are at 130 when the jungle drums start up behind your head...... The clearance you have should be fine

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