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  #11  
Old 04-16-2018, 06:18 PM
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Originally Posted by scard View Post

I love this thread. It drives me bananas.
You sure that is a drive, not a putt?
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  #12  
Old 04-16-2018, 06:24 PM
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Quote:
Originally Posted by Mike S View Post
You sure that is a drive, not a putt?
It is Monday for us workin' folk, which means, after hours, I'll see just how far I can make this putter drive .
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  #13  
Old 04-17-2018, 07:05 AM
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Originally Posted by scard View Post
Oh, the horror, "with a good steel rule". Tell me it ain't so!
Oh ye of little faith...

When jigged in a fixture this AM, and measured with the trusty digital caliper, my "about 13.000" was 13.005". Both 73555's were the same length.

The flats on both ends of one sample were about 0.160 dia, while the other pushrod was more like 0.140 on one end and 0.175 on the other. Those measurements are necessarily by visual comparison to a micrometer, with magnification. Nominal ball diameter is assumed to be the same as the tube, 7/16".

Given 0.160 flats, length of material removed would be 0.0152 per end, or 0.0304 total. Add it to 13.005 and we have 13.0354", very close to the 13.034" listed as "Approximate Length".
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  #14  
Old 04-17-2018, 07:17 AM
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It seems like "theoretical length" (the length if the flats weren't there) would be a better phrase. But there's really no way to actually measure that, is there?
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  #15  
Old 04-17-2018, 08:36 AM
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Originally Posted by scard View Post
Oh, the horror, "with a good steel rule". Tell me it ain't so!

I'm starting to deliver reverse engineered dimensions to 5 decimal places these days with the appropriate $$$$ attached. THEN the customer can finally decide on their TOLERANCE and PRECISION.

I love this thread. It drives me bananas.
5 places!?! What are you in to? I can't imagine what that would cost to manufacture.
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  #16  
Old 04-17-2018, 09:05 AM
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Originally Posted by snopercod View Post
It seems like "theoretical length" (the length if the flats weren't there) would be a better phrase. But there's really no way to actually measure that, is there?
Looks reasonable to measure the pushrod flat-to-flat and add 0.030" to match the listed length. Ya'll measure some and let's see.
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  #17  
Old 04-17-2018, 09:59 AM
Electrogunner Electrogunner is online now
 
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Default Dry tapper clearance

My engine builder had a go-no go gauge that he uses to determine pushrod lengt, just double ended feeler gage really . Did not seem very scientific as the clearance range is rather large and I think there were only 4 or 5 pushrod lengths to choose from. Basically he looked at it and said order this for this one and that for that one. Had em next day shipped and everything was installed and clearances were within spec. Seemed to me these engines were built like a ak47 with quite large tolerance in the valvetrain. Just another data point not a sermon.
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  #18  
Old 04-17-2018, 10:44 AM
lr172 lr172 is offline
 
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no answer here, but an idea. When I had pushrods made for the IO-320, I used an old one for a reference and sent them to the company with a desired increase or decrease measurement for each and got exactly what I wanted. They use a special tool for measuring them and I don't know what the measure point is.

Whenever I needed pushrods for auto engines, I made an adjustable pushrod and took measurements from that. I would always send the adjustable unit with a description of how I took the measurement so they could compensate for that or simply explained the type of ends that my adjustable unit had.

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Last edited by lr172 : 04-17-2018 at 10:47 AM.
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