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Author Topic: A65 Cylinder Head  (Read 383 times)

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Mike Farmer

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A65 Cylinder Head
« on: 12 July, 2022, 12:44:23 »
 :) :) :)

Just seen the new BSA mag and particularly interested in the Cylinder Head Repair by Dave Brady. Well done there. Remarkable that we both bought rods at about the same time, but I have not had the same success. Life. I was ok with plate but no good with castings. Why????No idea.

An interesting point---I have had A50/A65's since the late 60's and it wasn't until about 18 months ago that I knew the head washers were 'Special' so lord only knows how many times I used ordinary ones.

Another point maybe of interest, I have used Cap Head bolts instead of the normal Hex Hd. easier to get to on the awkward ones.

Mike 8) 8) 8)
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ChrisG

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Re: A65 Cylinder Head
« Reply #1 on: 13 July, 2022, 11:54:15 »
Mike, if the cap screws have the same surface area underneath the head as a bolt then no problem except check the tensile strength of them. Most are grade 12.9. Bearing in mind the hex bolts specified are EN14B which I stand t be corrected is T grade? Probably the main reasons for the recession/cracking are this washers as mentioned and not using a torque wrench to torque them down properly resulting in overtightening. Visions of typical young owner doing the job in the sunshine, in the back yard with a box spanner, rod and a length of iron gas pipe as a lever spring to mind. (Hey, that sounds like 1970s me!)
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Mike Farmer

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Re: A65 Cylinder Head
« Reply #2 on: 14 July, 2022, 21:33:45 »
 :) :) :) :)

Hi A couple of interesting points there. I dont know the spec of the cap heads. However I somehow doubt that wth the torque specified the caps will dish the special washers,

Another point here. learned the hard way.  Situation: - Engine rebuilt- rebored the works--Head resurfaced- refitted head started beaut-oil leak at head gasket- Re torque. Start up oil leak-- remove and replace head--oil leak. Much scratching of the noddle. Go through the obvious Check the bolts=fine. Check the threads in the barrells= Put a tap down the threads just to make sure==Whoa there tap will not go right in. In one bolt hole there was a layer of some sort of crap hard enough that the bolt tighened up and toeque up against it but the bolt was not going in far enough to exert full pressure. Cleaned all the holes out properly--refitted head-- motor went brrrrmmmm and oil leak cured. AS I dug them all out as a matter of course I dont know how many where affected or by what. Still ok.

Mike 8) 8) 8) 8)
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