Robert,
2.781 = 2 and 781 thousanths of an inch
0.020 = twenty thousanths
if standard = 2.780 twenty over would measure 2.800
thirty over would be 2.810
The standards normally state +/- a certain amount so if it were +/- .002
or two thousanths 2.778 - 2.782 would be OK.
The book I have lists standard bore as 2.781 inches 70.64mm if you
measured correctly your bores are standard. If this is a brand new
rebuilt engine it has been sleeved to bring it back to standard. If it
is a used engine and you are measuring at the top which has no wear
because the piston does not reach the top and need to measure about 2
inches down from the top to get a proper reading.
Hope this helps.
Peter S.
>Date: Wed, 3 Feb 1999 13:52:20 -0500
>To: spridgets@autox.team.net
>From: robert weeks <robert@woozy.com>
>Subject: dumb question - or what's 20 thousanths of an inch?
>Reply-To: robert weeks <robert@woozy.com>
>
>Hi,
>
>Actually it's me that's dumb, not the question. I borrowed my friends
dial
>calipers and I have no idea if I am reading them right:
>
>The Bently book lists 2.78 as the proper bore for a 1275 cylinder bore,
>when I measured them I came up with 2.781 - 2.782. Is this within the
>acceptable range for a "standard" bore? If it is, just for future
knowledge
>what would the reading be if it were bored out 20 thousanths over or 30
>thousanths?
>
>Please excuse my ignorance, I'm fine with 32nds, 64ths, etc, but my
mind
>has a hard time with thousanths.
>
>Robert Weeks
>
>1969 Midget (daily driver)
>1968-70 Spridget (two cars welded together)
>1974 Midget (parts car?)
>
>http://www.woozy.com/midget/
>
>
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