Author Topic: Do I need to retension head studs?  (Read 632 times)

Online hdawson

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Re: Do I need to retension head studs?
« Reply #15 on: 09.01. 2019 07:12 »
After my rebuild last year and half a dozen short rides I blew my head gasket.
Lucky that I had a spare on hand so I would be more cautious in the future.
Rocker box fitting is an art that improves with repetition (like with most tasks) and after making every mistake I now find it a satisfying challenge.
Cheers,
Hadrian.

61 BSA Super Rocket (cafe).
51 Matchless G9 Clubman.
81 Suzuki GSX 750 ES.
02 Triumph Sprint.

Online muskrat

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Re: Do I need to retension head studs?
« Reply #16 on: 09.01. 2019 08:32 »
G'day Scotty.
A heat cycle is getting it up to operating temp and letting it cool. 15-20 minute ride would do. Idling isn't good for the rings and bore.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Online KiwiGF

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Re: Do I need to retension head studs?
« Reply #17 on: 09.01. 2019 09:33 »
I reckon This is one of those topics that is unlikely to result in a clear consensus  *dunno*

The first time I built my “basket” engine it blew a head gasket when it done more than 500 miles, and over 10 rides. I fixed it (using the same solid gasket, re annealed) and worked out that the root cause was that my (nearly new) torque wrench was not accurate. It was over reading by over 40% so the bolts were WAY under tightened, but interestingly it held together for quite a while, and probably only blew because being the bolts loosened off even further, I guess because they were so loose to start with, with some ending up little more than finger tight, so I guess In my experience the applied torque is not super critical, provided they stay done up!

After fixing that and a few more miles it dawned on me that I’d used the same wrench on the big ends  *problem* *problem* *problem* *problem* *help* *pull hair out* so (after a trip to the pub) I stripped the engine to re torque those.

Anyway, the point is that people’s experiences will differ depending on the accuracy of torque wrenches, flatness of surfaces, type of gasket, how many heat cycles or miles before being re torqued, oiled or non oiled bolts, whether the head is iron or ally, washer hardness, etc etc

Regardless of that, like prior posts I agree the “gold standard” would be to re-torque (with calibrated wrench) all the head bolts after (insert your own number, maybe 10?) heat cycles or (insert your number, maybe 500?) miles which ever comes first. Unless I experience an unexpected blown gasket I’ll not be doing it though!


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Offline cyclobutch

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Re: Do I need to retension head studs?
« Reply #18 on: 09.01. 2019 13:03 »
I always retorq on Guzzis, but then despite having to remove the rocker assembly you don't get all of the rocker box foolishness.

Talking of which, the replacement for my lost comb has turned up so all being well I'll be popping the (very) top to fix an oil leak some time over this coming weekend.
Various, including ...
'58 Iron Head Flash Bitza


Offline scotty

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Re: Do I need to retension head studs?
« Reply #19 on: 09.01. 2019 17:30 »
Ahhh I see

Thanks Musky

S

Scotty
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Online Rex

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Re: Do I need to retension head studs?
« Reply #20 on: 09.01. 2019 17:42 »
This is a standard procedure on Triumphs, but sensibly you can get to all the bolts without a major strip-down.
I'm worried now, but I think I'll wait until the Spring and see how it goes on the A7, which has a Drags composite gasket installed. I'll fit a solid copper item next time though.