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Rod length C-C

Old 07-20-2018, 04:14 AM
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Rod length C-C

...And does anyone know the rod length center to center off hand?

Thanks again
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Old 07-20-2018, 10:06 AM
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Not a spec available from Honda

Measure a known good rod or call and speak with a crank shop, Crank Works, Falcon ect and ask.

Might also look at aftermarket rods for this application and if they advertise it as a stock replacement see if they will cite the center to center length of their rod
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Old 07-20-2018, 11:42 AM
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I have an extra set but they're being balanced etc. at the moment. I'm making some calculations for cam profile and such, having those numbers on hand would be good. I suppose I'll have to wait and find something else to tinker with.

Thanks

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Old 07-22-2018, 07:08 AM
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I have a spare set on hand and did a quick c-to-c measurement and (IIRC) found it to be 130mm (or close to it, which would give a 2:1 rod:stroke ratio) ; must mention that I used a simple ruler and eyeballed it, however
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Old 07-22-2018, 08:24 AM
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Thank you!
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Old 07-22-2018, 08:40 AM
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So I pulled a rod from my spare motor...
But Im puzzling at how to measure center to center with what i have on hand....
I could mount it on the mil, run the length touching a ground .250 pin on the OD of both ends, take the DRO numbers and do the math based on measured OD of both holes.. It would get a measurement, but nothing I would call accurate as there are too many possible errors involved.

If I have some spare time,,,, I could machine some plugs for both rod ends mark them both for center... and use precision ground, pointed pin to again use the DRo and measure point to point...
Still not what id call really accurate.

If I still had access to the SUNNEN rod machine I did 20 years ago it would be an easy task, but I don't..
So what to you need for accuracy? .01"? .001"? .0005"?

Last edited by E.Marquez; 07-22-2018 at 12:33 PM.
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Old 07-22-2018, 09:45 AM
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Now that's what I'm talking about, Yankee ingenuity. The way I measure mine is usually when I'm balancing the rods, mostly from convenience. I have a balance jig made up for the scale so I can check the weight of each end. I have a plug that fits the large and small ends with dimple dead center. I measure from dimple to dimple for each rod without a bearing installed, and all caps torqued the same. Now for mine-- the rods that are actually going in the motor, .000" is my spec, but in this case I'm working numbers for cam specs so length and ratio is really the key. Now this doesn't necessarily mean a motor will explode or not, I just like to have those specs on hand so I know all that I can about my internals.

Thank you again

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Old 07-22-2018, 07:54 PM
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This should get you in the ball park. I just hope that I can explain this well enough to make sense to every one.

1. Take a rod, without the cap, and place a straight edge across the crank end. You now have the centerline for the big end of the rod.

2. Next take a piston pin and insert it into the small end of the rod.

3. Measure distance between bottom of piston pin and the straight edge making sure to keep parallel to the con rod.

4. Measure diameter of piston pin then divide in half.

5. Adding 3 and 4 together should equal center to center rod length.

A good digital caliper should be sufficient to get you close enough.
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