Ok here's the deal on rod bolt stretch.
New style rod bolts have a small center depression in both the head of
the bolt and the other end of the bolt.
The stretch gauge is nothing more than a dial indicator reading in .001
increments with the ability to estimate (space between the marks, in
other words) to a ten thousand.
Each end of the gauge, the dial indicator and the other end of the c
clamp like device, has a pointed tip that fits into the depressions on
each end of the rod bolt. Thus you are measuring total stretch of the
bolt regardless of the length.
Now in my view, the critical factor here is the mfg's spec on how much
stretch for that bolt in that application. Each set of bolts is
packaged for a particular rod/engine and the mfg tells you with a little
slip of paper how much stretch is needed.
Also included in the package is a small pack of a moly lube.
Instructions say lube with this and if no stretch gauge is available,
torque 3 times to 40 PSI, release each time and stop with the final 3rd
torque. The instructions also say to measure each bolt BEFORE
installation with a mike and measure each usage to make sure the bolt
has not stretched beyond yield. Toss away at that point.
Larry Dent
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