Crank specs
Thread Starter
Registered User
Joined: Jun 2009
Posts: 225
From: Berkeley, CA
Car Info: LGT Wagon
Crank specs
The book says the out-of-round limit for crank rod journals is only .0001" and taper is .0002". This is right at the resolution limit of most mics which makes it seem like a ridiculously low limit. Mine of course are much higher .0007" and .0006" respectively.
The shop that polished the crank says this is okay as long as the out-of-round and taper are smaller than my oil clearance. I'm targeting my oil clearances on the rods and mains to be .0015". The only information I can find online is about domestic v8's and they say as long as the out-of-round and taper are less than .001", it should be okay.
What do the experienced subaru engine builders on here say is a reasonable limit and why? If I run it with these specs am I increasing the risk of a spun rod bearing or is this just going to increase the oil flow through the bearing? If I spend the money to get it ground, will the machine shop be able to hold it to any tighter specs than it has now?
My mains are pretty much spot on for run-out and taper except for the #1 journal. The crank has 75k on it and the reason it is out is because I blew the turbo and drove it home with metal debris circulating in the oil. And yes I know I can get a new crank for $300 but why spend the money if this will work.
It's out of an EJ255 Legacy GT.
The shop that polished the crank says this is okay as long as the out-of-round and taper are smaller than my oil clearance. I'm targeting my oil clearances on the rods and mains to be .0015". The only information I can find online is about domestic v8's and they say as long as the out-of-round and taper are less than .001", it should be okay.
What do the experienced subaru engine builders on here say is a reasonable limit and why? If I run it with these specs am I increasing the risk of a spun rod bearing or is this just going to increase the oil flow through the bearing? If I spend the money to get it ground, will the machine shop be able to hold it to any tighter specs than it has now?
My mains are pretty much spot on for run-out and taper except for the #1 journal. The crank has 75k on it and the reason it is out is because I blew the turbo and drove it home with metal debris circulating in the oil. And yes I know I can get a new crank for $300 but why spend the money if this will work.
It's out of an EJ255 Legacy GT.
Thread Starter
Registered User
Joined: Jun 2009
Posts: 225
From: Berkeley, CA
Car Info: LGT Wagon
I would rather spend the $125 to get it ground since it would be:
1) $155 cheaper
2) I can set my clearances to the wide side of spec instead of just taking what the new crank gives me.
1) $155 cheaper
2) I can set my clearances to the wide side of spec instead of just taking what the new crank gives me.
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