Head bolts life span.

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Dec 28, 2022 | 03:45 PM

Scotty p

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From: Sebastopol

Head bolts life span.

So on these 45 flathead Harley’s , or any Harley what is the recommended usage on head bolts?
I know bolts cans stretch, so how times is it okay or not okay to reuse? Nothing my sucks more than a broken head bolt.

Dec 28, 2022 | 04:26 PM

johnjzjz

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From: la la land jerzey

The original bolts was grade 8 or 9 from the WW2 issue - 10 of todays head bolts are not as strong as one of those - from use and the amount of engine rebuilds i have seen the wrench head rounded ( a bit ) but the bolt and threads were fine

Dec 28, 2022 | 05:11 PM

Scotty p

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From: Sebastopol

Ok got that, but is there any norm for the number of times they can be reused ? Or just used them until the bolt head starts to round off?

Dec 28, 2022 | 05:15 PM

stixvrad

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From: Northern New Jersey

Quote:

Originally Posted by Scotty p

Ok got that, but is there any norm for the number of times they can be reused ? Or just used them until the bolt head starts to round off?

They're not torque to yield ( TTY) so IMO if they look in good shape they should be fine. If you suspect any, maybe measure the lengths with a dial caliper ( from under the head to the other end) and make sure they are all around the same length.

Dec 28, 2022 | 05:24 PM

downzero

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Bolts have to stretch or they can't clamp the parts together. If they haven't been overtorqued, damaged, or corroded, they should have infinite life.

Dec 28, 2022 | 05:48 PM

Scotty p

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From: Sebastopol

Now that makes sense. After wenching on cars for 40 years I was thinking it’s got to the same.
But being new to working old a Harley one can never assume anything.

Thanks 👍everyone for the feed back, as mommy always said many brains make for better success!!!

Dec 29, 2022 | 07:26 AM

Architect

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Torque to 65 ft/lbs and you are good to go. If the motor is in the frame, one of the rear head bolts is not accessible with a torque wrench.

I recommend you find a chaser tap to clean all the holes in the cylinders before installing the heads.