PDA

View Full Version : Connecting Rod Balancing Fixture



98Dak408
07-15-2019, 11:05 AM
Getting ready to swap out the cast crank, I-beam rods…and Hypereutectic pistons in my 408 for a completely forged set up. The parts are fine but I want a stronger rotating assembly now.

In order to balance the new rotating assembly, I picked up the Proform Rod Balancing Fixture on sale for $164.95 shipped. However, I quickly found that the fixture out of the box is not really ready to balance rods. When installing and removing rods many pieces of the fixture slide around making erroneous readings each time the rod is weighed: the big end rod collars slide back-and-forth; the pivot bar slides back-and-forth and may fall off; the platform may not be level depending upon the table level; the scale may move around upon the fixture; the part that sits on the scale slides around on the top of the scale; and the whole fixture may slide around on the table. When various pieces come out of alignment the readings change accordingly. Therefore, each time I weigh the same rod I get different readings.

So, I modified the fixture to alleviate those problems: installed set screws in the pivot arm and big-end rod collar; installed adjustable leveling feet with rubber pads in order to level the fixture and keep it from sliding around; installed rubber pads beneath the fixture piece that rests upon the scale; and made a railing piece to keep the scale solidly in one place that is adjustable depending upon rod length. Much better results. I now have a more reliable set-up in which to balance the rods…and pistons to determine a bob weight. Then, I can take the crank and the bob weight calculation to a crank balancer, and just have the crank balanced on their high-dollar machine. One balance job and this modified fixture is paid for.

https://www.jegs.com/i/Proform/778/66844/10002/-1

https://i.imgur.com/Ol5wmVh.jpg

https://i.imgur.com/CDG2K2l.jpg

nitroram33
07-15-2019, 01:01 PM
:biggthumpup:

99dart
07-16-2019, 01:15 PM
Cool beans! :biggthumpup:

arro222
07-16-2019, 08:50 PM
If you're in the business, it's important to have all the right stuff. At least in can be paid for.

TurboJoe62
07-19-2019, 05:11 PM
Nice job!

krs1r/t
07-20-2019, 01:59 PM
:biggthumpup: