85.5mm Cometic .030" on an 84mm bore?? - Miata Turbo Forum - Boost cars, acquire cats.

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85.5mm Cometic .030" on an 84mm bore??

Old 02-07-2016, 05:04 PM
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Default 85.5mm Cometic .030" on an 84mm bore??

I see mixed things about using an oversize hg on builds... question is, what's too big?
Not sure how/why i ended up with a 85.5mm bore Cometic for my 84mm bored block.
What neg effects would i see on this turboed block if i use it? Pass or fail?
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Old 02-07-2016, 05:17 PM
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The only answer is to bore your block to 85.5
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Old 02-07-2016, 05:48 PM
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Oh man... well, got all disassembled and headed back to machine shop... guess that means i need to buy another set of pistons too. Anyone need some 84mm supertechs?

I'll do this if i get my 2 gps units in the mail tomorrow

I *could* get the right gasket - but dont really feel like shelling out another $120ish - ya know?
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Old 02-07-2016, 05:50 PM
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If the 84mm pistons get sent to me then your gps units can be in overnight mail tomorrow at 8am.

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Old 02-07-2016, 06:22 PM
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Originally Posted by aidandj View Post
If the 84mm pistons get sent to me then your gps units can be in overnight mail tomorrow at 8am.

lol
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