Author Topic: C12 valve gap  (Read 283 times)

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Online haddy

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C12 valve gap
« on: October 07, 2020, 01:55:50 pm »
Hello
I have seen a graph of varios models valve gap but i cant find it.I want to find out the valve gap of a C12
haddy

Online Cosmikdebriis

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Online camman3

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Re: C12 valve gap
« Reply #2 on: October 07, 2020, 02:52:45 pm »
Don't forget to check whether you have ramped cams fitted or not (most probably have), as different clearances and setting points.
Graham
1957 C12
In sunny (sometimes) Christchurch, Dorset, UK

Online haddy

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Re: C12 valve gap
« Reply #3 on: October 09, 2020, 01:19:41 am »
Yes checked using Owens method and it has older type cam.









Online Owen

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Re: C12 valve gap
« Reply #4 on: October 09, 2020, 06:37:08 am »
Happy to help
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online timsdad

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Re: C12 valve gap
« Reply #5 on: October 09, 2020, 08:34:07 am »
It's BSA's method, plucked straight out of their Instruction Book, as there are no typos in it!

Ray
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Online Cosmikdebriis

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Re: C12 valve gap
« Reply #6 on: October 09, 2020, 09:45:07 am »
It's BSA's method, plucked straight out of their Instruction Book, as there are no typos in it!

Ray

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Online Owen

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Re: C12 valve gap
« Reply #7 on: October 09, 2020, 12:26:16 pm »
I didn't re invent the wheel.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online timsdad

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Re: C12 valve gap
« Reply #8 on: October 10, 2020, 07:35:46 am »
Going back to the original query, there were no 250 ohv C12s built with the early cams.

The non-ramped cams were already old technology for the Cs by the time the C12s were introduced and dealers were not supposed to sell any of the old type cams that they may have had on the shelf as spare parts for even the distributor model C10s and 11s.

The only possibility of it having a non-ramped cam, Haddy, is if a previous owner has rebuilt the engine using a cam from an early C11G.


Ray
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Online haddy

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Re: C12 valve gap
« Reply #9 on: October 13, 2020, 02:47:48 am »
I gave the engine number earlier it is a 51 C11 with a C12 top end. So naturally enough it came with a 51 cam.
If you look through net pics of rigid frame models some have C12 top ends. Not for the purest but to my mind look much better and those extra fins cant harm.
haddy

Online Owen

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Re: C12 valve gap
« Reply #10 on: October 13, 2020, 06:30:19 am »
What do you mean by C12 top end?  The only difference I can think of is the oil feed to the rockers?
I thought early C11 barrels had less finning on the push rod tunnel. With the introduction of the C 11g the barrel and head had longer studs,. Not forgetting the hole for the head steady.
« Last Edit: October 13, 2020, 06:38:37 am by Owen »
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online timsdad

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Re: C12 valve gap
« Reply #11 on: October 13, 2020, 08:33:27 am »
The title just says 'C12 valve gap', with no mention of engine number, year or C11, so I assumed it's a C12 the query referred to, Haddy. The C11 and C12 cams are not interchangeable.


Ray
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Online haddy

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Re: C12 valve gap
« Reply #12 on: October 14, 2020, 11:22:18 am »
Hello Ray
Yes i think i confused things by opening a new topic.
My main query was when did the fully fined top ends come out (see pics)c11...c11g...c12
haddy