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A65 head screwed on too tight? #690384
04/03/17 9:48 pm
04/03/17 9:48 pm
Joined: Mar 2006
Posts: 3,718
gastonia nc
R
raf940 Offline OP
BritBike Forum member
raf940  Offline OP
BritBike Forum member
R
Joined: Mar 2006
Posts: 3,718
gastonia nc
here ere a hypo-thet-I-cull situation ...suppose a person (not I!) felt like despite a high dollar torque wrench that they had screwed the bolts down too tight on an BS A65 head...not sure of exact lbs. ft......and wanted to loosen them all up and start over...I say let sleeping dawgs lie and redo after some miles but mebbe I am wrong what say ye?
thanks fellers


1972 Triumph T120
1968 BSA A65
1968 MGB Roadster
1979 Chevrolet Camaro Berlinetta
1969 Honda Mini Trail
1939 farmall f30 tractor
2004 Honda Shadow Aero
1972 BSA Thunderbolt
1975 yamaha xs650b
1972 Norton commando project
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Re: A65 head screwed on too tight? [Re: NickL] #690414
04/04/17 5:50 am
04/04/17 5:50 am
Joined: May 2010
Posts: 2,579
Illinois, USA
TR6Ray Online content

BritBike Forum member
TR6Ray  Online Content

BritBike Forum member
Joined: May 2010
Posts: 2,579
Illinois, USA
I'd redo it before you run it. The torque values are set up to give you the proper amount of bolt stretch. The spec takes into account that more bolt stretch will take place as the alloy head expands thermally more than the bolts do. So, say you are on the brink of disaster, the bolts will get stretched more when the engine is at operating temperature. Will that be enough to ruin your engine? frown


'64 TR6R Plus some Twins from other countries (U.S., Germany, Japan)
Re: A65 head screwed on too tight? [Re: raf940] #690421
04/04/17 9:18 am
04/04/17 9:18 am
Joined: Aug 2001
Posts: 3,874
argyll. scotland, uk
gavin eisler Offline
BritBike Forum member
gavin eisler  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 3,874
argyll. scotland, uk
For curiosity sake, I would mark across the outer 4 head nuts and studs with a white line ( correction fluid) slacken and retorque to spec. If there is a significant difference from old tight to new tight I would check the hard to get ones, if not leave well alone.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: A65 head screwed on too tight? [Re: raf940] #690428
04/04/17 11:18 am
04/04/17 11:18 am
Joined: Sep 2008
Posts: 727
angeles city, rp
J
jaycee Offline
BritBike Forum member
jaycee  Offline
BritBike Forum member
J
Joined: Sep 2008
Posts: 727
angeles city, rp
its just my two cents worth but i personally would probably buy new bolts and not worry about it and throw the old in the bin. of course you didnt say how much they were overtorqued. and you cant make an informed decision with out knowing what the max torque is for those fastener's are based on material, diameter, and whether they were installed lubed or dry. i've never seen a torque for british bolts but surely one exists . its quite possible that max torque is quite different than what bsa stipulated to install the head

Re: A65 head screwed on too tight? [Re: raf940] #690516
04/05/17 4:09 am
04/05/17 4:09 am
Joined: Aug 2001
Posts: 4,444
Owego, NY, USA
Mark Z Offline
BritBike Forum member
Mark Z  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 4,444
Owego, NY, USA
raf, why do you think they're too tight? My Chilton book says 31-33 for all bolts and nuts, and that's what I've always tightened mine to, but others have argued that it should be less. That's way more than on a Triumph, if that's what you're used to. More importantly, were they tightened according to the prescribed sequence, and all to the same amount? If not, I would undo it all and check the head for flatness, maybe replace the bolts if you have any doubts about them.

If they're all even and not terribly tight, I would go with it. If it's a fresh engine, you'll be re-torqueing at some point, and you should always crack all the bolts and nuts loose before you re-torque.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.

Moderated by  Alan_nc 


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