Author Topic: Stamp Marks ? Piston  (Read 747 times)

Offline LJ.

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Stamp Marks ? Piston
« on: 28.02. 2012 11:14 »
We know 'HC' stands for 'High Compression' But... Why HHC? surely not High High Compression? Often these double 'H's along with a single 'C' are seen under the engine number can anyone explain why?
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Online Brian

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Re: Stamp Marks ?
« Reply #1 on: 28.02. 2012 11:36 »
This has come up before somewhere.

I think the HC stands for high compression and HHC means it also has the 357 cam. I think !

Offline Beezageezauk

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Re: Stamp Marks ?
« Reply #2 on: 28.02. 2012 16:13 »
I agree with Brian.

I remember somebody telling me this several years ago and I've always believed it.

Beezageezauk.

Offline olev

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Re: Stamp Marks ?
« Reply #3 on: 29.02. 2012 06:27 »
Maybe not??
Did the Super Flash plunger have a 357 cam?

http://www.a7a10.net/forum/index.php/topic,5179.0.html
cheers

Offline Rocket Racer

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Re: Stamp Marks ?
« Reply #4 on: 29.02. 2012 06:35 »
The extra H for hi lift cam also applies to the 356 not just the 357.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline olev

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Re: Stamp Marks ?
« Reply #5 on: 29.02. 2012 07:12 »
I've got a set of 1954 star twin cases on the shelf.
It only has HC stamped on it.
I'm sure the took a 356 cam.
cheers

Offline saltbox Alf

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Re: Stamp Marks ?
« Reply #6 on: 04.03. 2012 16:48 »
HC, HHC, I got my dating certificate at last and and it's '62 S'procket exported to usa then back via Germany, (long story) However the c/ case has just got an H stamped on it. Wonder if it means not much compression!!
 I have heard that on occasion the apprentice was let loose to stamp the cases and on a post on another forum the lack of or miss matching of numbers was discussed , wrong size font and double punched have been seen.
As I understood it HC equated to 8.5 to 1 and HHC anything above. Plus the different cams.
But there are here more knowledgable  than I.

Cheers
I like bike, especially my 61'SR