Length of "extra" Lightweight head bolt

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clanger9
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Length of "extra" Lightweight head bolt

Post by clanger9 »

Please can anyone tell me the length of part number 042196? It's the "extra" cylinder head bolt on a Lightweight and is described in the parts list as "Bolt, cylinder head, 5/16 in. by 22 TPI"
bolt.jpeg
I can't seem to find it among the parts for my engine rebuild. It's possible either that I've lost it, or it wasn't fitted to my engine in the first place. I don't recall it being there when I dismantled it.

Unfortunately the part isn't available from club spares, so I'm hoping I can find an alternative...
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Ozmadman
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Re: Length of "extra" Lightweight head bolt

Post by Ozmadman »

Yes 5/16ths BSF that wil be the problem. I would get a length of silver steel and make a stud up using a BSF die and use a nut at the top. I had a serious issue with mine where the thread in the barrel had been stripped, helicoiled and then stripped again by the P.O I presume. I couldn't drill it any deeper as it would show through the fins so I had to drill it out larger and the best way to make sure it would hold was to go to 10mm coarse thread which I did. Then I made a 10mm stud which I loctited into the barrel as even at 10mm the thread wasn't brilliant due to the size of the original hole. I then had to drill out the hole in the head to that size to accommodate the new size stud. Finally enlarge the hole in the gasket. Could still just about fit the head over the stud with the engine in the frame and all worked fine and actually it's more secure with a larger stud and nut in that position. Tightening the smaller bolt always seems a bit dodgy to me just don't tighten it up to the same torque as the studs!! Just needs nipping up. Will post a few pictures of my efforts when I get home later as the pictures are on my pc
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Mick D
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Re: Length of "extra" Lightweight head bolt

Post by Mick D »

Hi

Sorry if this sounds flippant, but isn't it fairly straightforward just to measure the depth and subtract a clearance?

Edited to add, in the light of Ozmadman's comment - Namrick have a fair selection of 5/16" BSF bolts available.

Regards Mick
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clanger9
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Re: Length of "extra" Lightweight head bolt

Post by clanger9 »

Not at all - I can certainly figure it out by measuring the depth, etc. 5/16" BSF x 3" seems "about right".

I could do with the dimensions of an original so I know how deep the bolt is supposed to go into the block. My guess is (as Paul says) that it doesn't need to be especially tight and it's just there to keep the oil feed to the head leak-free.
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Rob Harknett
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Re: Length of "extra" Lightweight head bolt

Post by Rob Harknett »

Are there no other such bolts that can be made to the correct length???
Mick D
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Re: Length of "extra" Lightweight head bolt

Post by Mick D »

Hi

See here for a 3" bolt - others listed

http://www.namrick.co.uk/acatalog/Home_ ... lts_4.html

Regards Mick
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clanger9
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Re: Length of "extra" Lightweight head bolt

Post by clanger9 »

Thanks for the pointers, all! I'll try a standard 5/16" x 3" BSF bolt and report back...
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Rob Harknett
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Re: Length of "extra" Lightweight head bolt

Post by Rob Harknett »

Always check holes for muck, which could stop a bolt tightening up. Too much effort trying to tighten could strip a thread.
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Re: Length of "extra" Lightweight head bolt

Post by cbranni »

My rule of thumb for minimum thread engagement............... diameter of thread x 2 for aluminium, casting or plastic and x 1.5 for steel.
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Janet
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Re: Length of "extra" Lightweight head bolt

Post by Janet »

clanger9 wrote:Not at all - I can certainly figure it out by measuring the depth, etc. 5/16" BSF x 3" seems "about right".

I could do with the dimensions of an original so I know how deep the bolt is supposed to go into the block.
If you can wait until tomorrow afternoon, I'll take mine out and measure it for you as long as you don't need it to be accurate to a thou.
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