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Old 10-01-2010, 03:13 PM   #1
grafton
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Member#: 187936
Join Date: Aug 2008
Chapter/Region: MAIC
Location: Fairmont WV
Vehicle:
97 Legacy w/12:1CR
07 WRB STi

Default semi-balanced internals?

I am in the final stages of prep before my high compression build:
ej251 honed to 3.9180" on all four cylinders
4 New oem "A" pistons PTW clearance is in the standard range for all 4
new ACL race main & rod bearings
sti 10mm oil pump
MY95 EJ22e dual port heads gasket match intake port and polish, ~1mm port and polish to exhaust side, short side radius and bowl work on IN/EX
New valves
Delta 200 grind cams
Solid lifters
Lite weight crank Pulley

my question is how closely are the stock internals balanced?

the closest i can get it is within 0.3g on one set of cylinders
the way i believe it should be set up:

#3 1162.8g - #4 1163.1g <- 0.3g off of each other
#1 1163.2g - #2 1163.2g


thoughts, suggestions, different piston/rod combo's?
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Old 10-01-2010, 03:21 PM   #2
rexworx
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have you measured the pistons and rods seperately? Swapping around pistons and rods may yield results closer to what your lookin for, if you havent already.
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Old 10-01-2010, 03:36 PM   #3
grafton
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97 Legacy w/12:1CR
07 WRB STi

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Quote:
Originally Posted by rexworx View Post
have you measured the pistons and rods seperately? Swapping around pistons and rods may yield results closer to what your lookin for, if you havent already.
yeah that's the closest i could get, the FSM says nothing about weighing pistons & rods i just want a smooth as possible motor using what i've got.

because i forgot to add it in the first post:
pistons:
P1 545.4g
P2 545.2g
P3 545.5g
P4 545.4g

rods (id'd via engravings)
LV 617.3g
LW 618.0g
LZ 617.7g
MC 617.8g

combo's
rod-piston
LV-P3 1162.8g
LZ-P1 1162.1g
MC-P4 1163.2g
LW-P2 1163.2g
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Old 10-01-2010, 05:10 PM   #4
nhsilversti
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holy crap justin, you almost sound semi intelligent.

heheheh

imo .3 is close enough unless you are going to turn really high rpms

gald to see its coming together
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Old 10-01-2010, 11:38 PM   #5
grafton
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97 Legacy w/12:1CR
07 WRB STi

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Quote:
Originally Posted by nhsilversti View Post
holy crap justin, you almost sound semi intelligent.

heheheh

imo .3 is close enough unless you are going to turn really high rpms

gald to see its coming together
rofl, thanks ted, did all the final tolerance checks today, assembly begins tomorrow. The motor wont spin past my lovely stock red-line of 6250, Just looking for every little gain i can make with what i've got to work with.
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Old 10-02-2010, 11:34 AM   #6
DSM_Outback
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Nice, try adding rod bearing weights too.
Most of the phase II cranks I've spun up were within a couple grams front to back.
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Old 10-02-2010, 12:14 PM   #7
grafton
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Vehicle:
97 Legacy w/12:1CR
07 WRB STi

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the crank is a cobb balanced, from a 2.0 stroker kit
i was more worried about my used rods/new pistons&rings

its going together this afternoon, this whole motor building thing is fun but i wouldn't want it as a day job
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