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FE Power Forums => FE Technical Forum => Topic started by: Fordman on November 30, 2023, 09:45:37 PM

Title: Advertised VS real world connecting rod weight
Post by: Fordman on November 30, 2023, 09:45:37 PM
How do manufacturers come up with the advertised weight of connecting rods?. I know what common sense tells me how it works. I have a rod fixture for balancing rods and an excellent digital scale. On the manufacturers box it reads recip/small end(273.2 grams), rotating/big end (560.8) total rod weight 834 grams. Put the rod itself on the scale 934 grams. Where is the additional 100 grams coming from. I'm missing something. Thanks
Title: Re: Advertised VS real world connecting rod weight
Post by: Barry_R on November 30, 2023, 10:25:13 PM
What do the big end and the small end each weigh when on the balancing fixture?
Title: Re: Advertised VS real world connecting rod weight
Post by: Fordman on November 30, 2023, 10:31:47 PM
That's an excellent question Barry.Talk about old age, I didn't occur to me to check.I just got the rods today and was reading the specs on the box and tossed a whole rod on the scale and it was 934 grams and my mind was , where did the extra 100 grams come from. I was just curious if this was a moot question and there was a quick answer like , they don't weight them with the rod bolts or something. I will break out the fixture tomorrow and see what it says. Thanks for the response.
Title: Re: Advertised VS real world connecting rod weight
Post by: Fordman on November 30, 2023, 10:34:04 PM
These are Molnar rods and even going on the website they advertise 834 grams total for these rods but my scale does not lie. They are 934.2 total weight. We will see what the fixture weight says VS advertised. Thanks again!
Title: Re: Advertised VS real world connecting rod weight
Post by: GJCAT427 on December 01, 2023, 05:56:14 AM
Someone with a fat finger who wrote the ad specs missed while typing.
Title: Re: Advertised VS real world connecting rod weight
Post by: blykins on December 01, 2023, 06:10:10 AM
I've never had a set of Molnar rods in the 900 gram range.   

I just went out and weighed a set of Molnar 6.800" "Power Adder" BBC rods.  They are advertised at 817g.  They weigh 788, with bolts, still in the bag.

Title: Re: Advertised VS real world connecting rod weight
Post by: 427mach1 on December 01, 2023, 06:57:36 PM
Dumb question for you....  What kind of readout does your digital scale have?  Is it a 7-segment LED display?  If so, is the lower left vertical segment on the "hundreds digit" burned out?  Missing this segment would turn an 8 into a 9.....
Title: Re: Advertised VS real world connecting rod weight
Post by: My427stang on December 02, 2023, 08:46:58 AM
Any chance you missed a TARE after you did each end?  My numbers are consistently right on the packaging and WAY under what you see with Molnars
Title: Re: Advertised VS real world connecting rod weight
Post by: Fordman on December 03, 2023, 04:14:33 PM
It was the scale. Apparently time for a recalibration!. I have a spare so I pulled it out, tossed the rod on it 834.7 grams. Mystery solved. Thanks for the input fellas. I appreciate it. Cheers!