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Author Topic: M8 Head bolts  (Read 441 times)

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MCE

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M8 Head bolts
« on: May 10, 2019, 12:01:47 PM »

FYI: The stock M8 head bolts should NOT be reused! They're a one-time use item. I don't know if Harley has released  any bulletins or not, just an FYI. The bolts need to be replaced each time, or get the S&S reusable bolts.

Just letting ya'll know. Blown head gaskets if you reuse the bolts.

I've had Two shops experience this. Harley has been quiet about it.
« Last Edit: May 10, 2019, 12:47:45 PM by MCE Performance »
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hrdtail78

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Re: M8 Head bolts
« Reply #1 on: May 11, 2019, 09:10:12 AM »

Had a 18 oil cooled just come in with blown he’d gasket.  Stage one only.
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MCE

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Re: M8 Head bolts
« Reply #2 on: May 11, 2019, 09:58:22 AM »

Had a 18 oil cooled just come in with blown he’d gasket.  Stage one only.

Not uncommon. Always use fresh head bolts (or S&S'). If the heads come off for any reason,
use new bolts.

Copper coat from permatex is a good idea too. Hang the gaskets up with a wire (tig rod, coat
hanger or whatever, give them a good coat both sides and let it tack up real good).

I used to have high compression Two-strokes blow (copper) gaskets frequently (with freshly
milled heads). That stopped it.

« Last Edit: May 11, 2019, 10:05:01 AM by MCE Performance »
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grc

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Re: M8 Head bolts
« Reply #3 on: May 11, 2019, 11:05:29 AM »


That's a good recommendation for any application that uses torque to yield style bolts.  That type of bolt was never meant to be reused, but many people either don't realize they have that type of bolt or just don't want to spend the money to replace them.  The latter usually find out the hard way that their penny pinching eventually costs them a lot more when they have to do the job over again.

One question for those who actually work on these engines; if you replace the TTY bolts with reusable bolts like those from S&S, what adjustments if any are you making to the H-D recommended torque process and spec?

Jerry
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Jerry - 2005 Cherry SEEG  -  Member # 1155

H-D and me  -  a classic love / hate relationship.  Current score:  love 40, hate 50, bewildered 10.

MCE

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Re: M8 Head bolts
« Reply #4 on: May 11, 2019, 11:57:56 AM »

That's a good recommendation for any application that uses torque to yield style bolts.  That type of bolt was never meant to be reused, but many people either don't realize they have that type of bolt or just don't want to spend the money to replace them.  The latter usually find out the hard way that their penny pinching eventually costs them a lot more when they have to do the job over again.

One question for those who actually work on these engines; if you replace the TTY bolts with reusable bolts like those from S&S, what adjustments if any are you making to the H-D recommended torque process and spec?

Jerry

Just follow the instructions S&S provides. Any S&S dealer can get these for you, (I can as well) FYI

Heat cycle the motor then re-check the TQ on the bolts is also good practice.
« Last Edit: May 11, 2019, 12:02:19 PM by MCE Performance »
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