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-   -   Slipping head bolts... better solution? (https://www.offshoreonly.com/forums/general-q/370862-slipping-head-bolts-better-solution.html)

87MirageIntruder 03-19-2021 09:19 AM

That was a great article. I learned something important here.

TomZ 03-19-2021 09:22 AM

Thanks Mike. I didn’t explain it right yesterday. I was only using that as a test when it started to slip. It wouldn’t even make that without slipping on a couple of them.

My usual method...

40# start point, 50#, 60#, 70#.


To note... they’re not all slipping. Two on one side, three on the other.

cheech 03-19-2021 09:51 AM

TomZ, you used 80 grit. That article said to use 60 per ARP's recommendation.
I know splitting hairs. For the sake of clarity as to what they do actually recommend.

Did you see another recommendation from ARP to use 80?

fbc25el 03-19-2021 10:26 AM

This problem seems like it has to be a problem with the threads in the block.

TomZ 03-19-2021 10:37 AM

80-grit was the coarsest I had here at home; it’s pretty rough though and thought it would be fine for the job. I guess I can get 60 and try it. I might just call ARP to figure out what the deal is.

fbc25el 03-19-2021 10:52 AM

I had the same problem you are having. Does it feel like the torque wrench is jerking? It was a problem with the threads in the block. I could not leave it alone till i pulled some of the threads out of the block. I should of gone to studs. I think the jerking is causing the washer movement.

sutphen 30 03-19-2021 11:01 AM

torque wrench's,I just use the 1/2" milwaukee impact gun,1 and done.:D joking
I do the 3 step torque,,never a problem,I also use multilayer gaskets.

TomZ 03-19-2021 11:29 AM


Originally Posted by fbc25el (Post 4782303)
I had the same problem you are having. Does it feel like the torque wrench is jerking? It was a problem with the threads in the block. I could not leave it alone till i pulled some of the threads out of the block. I should of gone to studs. I think the jerking is causing the washer movement.

I'm applying torque very smoothly and there is no jerking. I'm not bottoming out and have compared the OEM bolts to the ARPs... the ARPs (with the washer) are an 1/8th inch shorter. I have plenty of thread engagement.

I roll through the procedure and achieve, let's say, 50#'s. When I go to 60#'s, I apply the torque, it gets tighter, but then "gently" gives way about a quarter turn. I stop at that point. On the other engine (short bolt), this led to a broken bolt so I'm being extremely cautious. I don't want to hurt the block.

I'll get some 60-grit and try that I guess.

F-2 Speedy 03-19-2021 11:38 AM

make sure you thread seal the through holes

resurrected 03-19-2021 12:01 PM

I have felt a similar thing on an old Ford, it stretched the bolts. I was re-using old bolts.


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