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NOS cylinder head

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exvalvesetdabbler:
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 I have uncovered a NOS cylinder head that I had stowed in the loft 30 years ago.  Originally bought it  because mine had a few iffy threads for the rocker cover bolts.

What I'm not sure on is the valve seats. Valve guides are present.  Looking at the parts list it does show valve guides as being  included in the part number and available separately.  If it is a factory fresh head would the valve guides have been reamed to size an the seats ground concentric with the guide.

Taking a used ex valve it goes in quite easily, just the lightest of a push and gravity does the rest.

The reason for it being cheap at the time is the exhaust port stud holes are untapped.  M5 drill bit drops in M5.5 is a tight fit and only goes in a few mm.  So probably right for tapping.

Regards
Dave

Bryanj:
Yes the guides and seats were done at factory and the exhauts studshave "self tapping" threads on the head end but personally would tap 6mm and fot m6x50 stainless studs from fleabay

exvalvesetdabbler:
Thanks Bryan,   Already have some studs that I made from 316 stainless but I chickened out when it came to extracting the ones from the working engine.

Edit.  I tried removing studs from a scrap head, 4 came out, one snapped off - gave up but at least I had an old one for a pattern.

Thanks
Dave

Laverda Dave:
Come on Dave, put me out of my misery......how much was that NOS head when you bought it 30 years ago?

exvalvesetdabbler:

--- Quote from: Laverda Dave on November 25, 2025, 10:19:01 PM ---Come on Dave, put me out of my misery......how much was that NOS head when you bought it 30 years ago?

--- End quote ---


Probably around the 30 quid mark, cheaper than helicoiling a load of threads if the worst happened.  Was a lot of money in them days!

There's a rocker cover with tappet covers as well, think it was cheaper. This was  before DSS got going properly. Most stuff was the small ads in MCN.

Dealers were just about giving stuff away in the early 90s

Dave.

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