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Old 04-21-2009, 10:58 AM   #1
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Default what size overbore pistons for rebuild?


as I wrote in the other thread it seems like my engine has a serious problem - supposedly a bad piston.

As it takes some time to order (and receive) all the needed parts, forged rods, forged pistons and arp head studs - what size overbore would you use.
(I think the answer will be - ask the engine rebuilder! But that makes the ordering roces even longer - because it will be end of the week until the engine is torn apart and take another two weeks until the new components have arrived - then install into the engine, install everything back into the car... bloody long time.

So - is there something like a common size (it's a 1,6l with OEM 78mm bore - so the option is 78,5mm or 79mm pistons) I don't think it does matter for the rods as they are the same for even 1,6 and 1,8 cars.

Thanks for your continuous help and advice!
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Old 04-21-2009, 11:14 AM   #2
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To quote Smoky

There is no substitute for cubic inches

the 79mm would be my choice, better chance the bores will clean up with the larger size as well.
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Old 04-21-2009, 01:12 PM   #3
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I went .5 over just in case something bad happened so I could hopefully bore again and retry.
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Old 04-21-2009, 01:16 PM   #4
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I went with the 79mm for my 1.6.
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Old 04-22-2009, 03:20 PM   #5
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Default Measure twice, cut once.

I would wait to see if your block needs an overbore. On my FE3, the previous owner had cracked a piston. When I sent the bare block to the machine shop, the cylinder walls were still 86mm. So I just had it honed and ready to drop in another set of 86mm pistons.
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Old 04-24-2009, 04:06 PM   #6
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1mm overbore used in my build...
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Old 04-24-2009, 07:37 PM   #7
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85.5 here. dont go more then 1-1.5mm to be on safer side
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