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Measured my crank. Not sure if it needs to be machined

Old 02-10-2012, 02:10 AM
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Default Measured my crank. Not sure if it needs to be machined

Hey guys,
I in process of building my engine. I got my micrometer today (used Starrett in great condition). After measuring my crank I'm not sure if it's good to go or should be cut.

For reference, standard journal specs:
main: 1.9661" - 1.9667"
rod: 1.7693" - 1.7699"

I'm just using the last 2 numbers, so
Standard mains are 61-67 tens
Mine are average 65, with some parts 64 or 66. Great!

Standard rods are 93-99 tens
Mine, however, are 95 on average, with about 20% of measurements at 94. Is that too close to minimum spec? Should I cut the rod journals?

I want to track the car and not spin bearings.
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Old 02-10-2012, 02:14 AM
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There is no way to tell until you get bearings and measure the actual clearance, but I've got the rod clearances larger than spec on the motor in Theseus and there are no issues with it.
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Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
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Old 02-10-2012, 02:19 AM
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That's what I figured. The block is in the shop for 2 weeks (apparently everyone gets machine work in the winter). I just wanted to decide NOW what to do - machine it or just get standard bearings and measure clearances and then see if its good.

Thanks!
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Old 02-10-2012, 08:19 AM
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I would take it to the machine shop and let them check it. You want to make sure its round as well. If the crank is in tolerance, they can polish it and you are good to go.
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