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Old 07-18-2005, 02:18 PM   #1
White 2.5rs
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Default parting block...having crank balanced..any hints/suggestions

my uncle owns a machine shop
www.enginemachineservicellc.com
he said for 80 bucks hed balance the crank to +/- 0gs
he said it balances it at 500 rpm

anything i should be worried about?

and do i need new rod bearings? ive got about 3k on the block
thanks
alex
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Old 07-18-2005, 08:11 PM   #2
no-coast-punk
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+/- 0g's doesn't happen unless you are at formula one levels.

Is he balancing the crank? Or the crank with the con. rods?

500RPM is far too low to show any imbalance in an OEM crank. Subaru cranks are very nice.
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Old 07-18-2005, 09:18 PM   #3
White 2.5rs
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i think he said he balances the rods separate from the crank

hmm...ill have to ask other places what rpm they do it at

thanks no coast
alex
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Old 07-19-2005, 12:58 AM   #4
no-coast-punk
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Most machine shops out there are great for American V8's. However OEM tolerances in modern Jap. engines is on the level of the work that most machine shops can do these days.

The faster they spin the rotating assembly during the balancing process the better. Small imbalances show up exponentially more at higher speeds. Don't bother wasting your time/money unless they balance the entire rotating assembly together (and make sure they index the bearings).

If you have access to a VERY accurate scale (anything more accurate than .1 grams will do nicely) and alot of patience you can balance all the reciprocating parts on your own. Weigh each component, find the lightest one, remove material from all other components until their weight matches the lightest one.

There's no reason EJ series engines that are properly built can't turn 10,000 RPM's.
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Old 07-19-2005, 01:14 AM   #5
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i have a scale that is accurate to like .005 oz or some INSANE amout
i can breath on it and it registers

i believe it goes all the way up to like 20 lbs or something

i might do that on the rods, thanks a lot for the advice

do you know of anyone that balances rods <at high rpms> and could possibly open up my oil journals a little?

thanks again mang
alex
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Old 07-19-2005, 02:08 PM   #6
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just talked to crawford performance
they said they see no need in opening up the oil passages assuming everything is fine

also they said they only balance at either 500 or 800 he couldnt remember...interesting

alex
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Old 07-22-2005, 06:44 AM   #7
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Actually the EJ205 and EJ25X shortblocks are not balanced from the factory. According to the balancer, the rotating assembly was pretty far off balance out of a stock STI EJ257 shortblock we sent last week.

Cheers,

Gary
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Old 07-22-2005, 10:18 AM   #8
White 2.5rs
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gary what speed do they balance them at <your balancer>
and what is the cost?

thanks
alex
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Old 07-22-2005, 11:38 AM   #9
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I balance cranks and in my opinion anthing anything less than a gram is pointless. You can get your components to achieve perfect balance put them together start the engine and oil starts to fling around one piston on compression the other exhaust the forces are not equal. You can't over balance for the sake of dynamic balance, you could coat the crank and rods in teflon maybe radius the edges of the crank. I would definetly balance the flywheel to.
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Old 07-22-2005, 08:22 PM   #10
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Quote:
Originally Posted by White 2.5rs
gary what speed do they balance them at <your balancer>
and what is the cost?

thanks
alex
I would also like to hear this information, along with how much had to be removed from the crank.
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