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Old 26 May 2011, 05:49 PM
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jamielove69
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Default Piston Types

hello my Scooby pals
ive been trying to find out what piston type belong to what engine
i have type A in my v3 STI engine
but in another engine i have:-
1 x type A MR2
1 x type A L72
1 x type B L72
1 x type B ME2

any wisdom would be appreciated
Old 26 May 2011, 06:09 PM
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merlin24
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Wouldnt worry too much about the MR2/L72 codes as they are batch codes.
Compression Height,shape of the crown/Crown ID marks and cast or forged would identify what engine they came out of.

Failing that, post some pics up


Mick
Old 26 May 2011, 07:00 PM
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they are in the engine. i dont want to sell the short block if the pistons arent right thats all
Old 26 May 2011, 08:00 PM
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i just managed to find out:-
The "B" piston has an outer diameter of 3.6211 to 3.6214 inches

The "A" piston has an outer diameter of 3.6214 to 3.6218

This way you can select an "A" or "B" piston to get the correct piston to sidewall clearance. Measure the bore, do the math, and select the correct piston for that bore

lol 3 tenths of an inch, that is mad!

Last edited by jamielove69; 26 May 2011 at 08:06 PM.
Old 26 May 2011, 08:33 PM
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bigsinky
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Originally Posted by jamielove69
i just managed to find out:-
The "B" piston has an outer diameter of 3.6211 to 3.6214 inches

The "A" piston has an outer diameter of 3.6214 to 3.6218

This way you can select an "A" or "B" piston to get the correct piston to sidewall clearance. Measure the bore, do the math, and select the correct piston for that bore

lol 3 tenths of an inch, that is mad!
i think you will find that is 3 thou, not 3 tenths.
Old 27 May 2011, 01:57 AM
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john5f
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Isn't it 3 ten thousanths of an inch?
Old 27 May 2011, 02:56 AM
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bigsinky
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no its 3 thousandths of an inch. after the decimal point it runs

1/10
1/100
1/1000

the difference between 3.6211 and 3.6214 is 3 thousandths
Old 27 May 2011, 03:48 AM
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Surely

.6 = tenths
.62 = hundredths
.621 = thousandths
.6211 = ten thousandths
.6214 = ten thousandths

so .6214 - .6211 = .0003

i.e. 3 ten thousandths

is that not right?
Old 27 May 2011, 07:53 AM
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jamielove69
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im an engineer so here goes - 0.1 is 100 thou. 0.02 is 20 thou. 0.003 is 3 thou. 0.0004 is 4 tenths. I was right.
Old 27 May 2011, 12:29 PM
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Me too. I think he misunderstood your earlier post as 1/10 instead of your abbreviation for 1/10,000.
I agree with you, how mad is that? The piston rings should handle that difference quite easily.
Old 27 May 2011, 12:42 PM
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oh i see. Ye that is mad. Sod honing someones bores. Lol just realise what ive just said :O
Old 27 May 2011, 01:11 PM
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bigsinky
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on looking at it again, you're right. it's 3/10000. so used to working in 1/1000s. i think 3/10000 is pretty close not to worry.
Old 27 May 2011, 01:27 PM
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Originally Posted by bigsinky
no its 3 thousandths of an inch. after the decimal point it runs

1/10
1/100
1/1000

the difference between 3.6211 and 3.6214 is 3 thousandths
Whats the difference between 3.8277 and 3.8280?
Old 27 May 2011, 01:45 PM
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bigsinky
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that would be 3/10000s you smart **** ****. i apologised, it was a mathematical genius' moment of weakness. what mechanics work to ten thou of an inch anyway?
Old 27 May 2011, 02:06 PM
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toooo many 0s to be meaningful. (Unless it was £££!).
Old 27 May 2011, 02:07 PM
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Originally Posted by bigsinky
that would be 3/10000s you smart **** ****. i apologised, it was a mathematical genius' moment of weakness. what mechanics work to ten thou of an inch anyway?

Now now
Old 27 May 2011, 03:38 PM
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