K1 rods ARP 2000 proper bolt stretch

[Mike T]

Are you guy's checking the actual stretch of the bolt?

Here's what I've found. According to a chart that K1 put out the ARP 2000 7/16 1.600 under head length bolt requires .006-.0064 stretch to do it's job as intended. A search on this board is showing various torque numbers for this bolt/rod combo and they are all far below what it actually took to get .0062 stretch on mine with ARP moly lube.

The stretch gauge is very cumbersome to use so I use the torque plus degree method carefully measuring each bolt before and after with a micrometer. It took between 90 and 100 lbs. Had three high quality torque wrenches on hand and they read the same so calibration is out.

 

[BEATAV8]

That's exactly why a stretch gauge is the best way to do it. (for me, its the only way to do it!)

After a few installation cycles to "break in" the threads, the torque to stretch relationship will change drastically. The torque to achieve the stretch will come way way down.

 

[Mike T]

The rods were run before in another build, they were torqued to 75 in steps based on #s posted. This time I went 30#s + 60 degrees and measured stretch. torque was off by 25#s +or - compared to the last build.

I would suggest to anyone who is building a new motor that they VERIFY what rod bolts they have and measure stretch instead of just torquing. The difference can be huge.

 

[bison]

Are you guy's checking the actual stretch of the bolt?

Here's what I've found. According to a chart that K1 put out the ARP 2000 7/16 1.600 under head length bolt requires .006-.0064 stretch to do it's job as intended. A search on this board is showing various torque numbers for this bolt/rod combo and they are all far below what it actually took to get .0062 stretch on mine with ARP moly lube.

The stretch gauge is very cumbersome to use so I use the torque plus degree method carefully measuring each bolt before and after with a micrometer. It took between 90 and 100 lbs. Had three high quality torque wrenches on hand and they read the same so calibration is out.

Yes. This is about what I've been seeing lately. Using the supplied lube I was between 90 and 95lbs when using the torque plus degree method. This applies to 7/16 thread bolts. Not 3/8!


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