Author Topic: A10 Big Valves - Rare?  (Read 3927 times)

Offline Woodrocket

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A10 Big Valves - Rare?
« on: 03.08. 2011 19:57 »
I have started restoring a 1962 BSA Super Rocket (North American model) and this is my first post.   The head accommodates the big intake valves (1.5?) and I cannot find a reference to these in my parts book and this resulted in an incorrect valve order.  I believe the code number is 67-0691.  Are these big valve heads rare?  The only place I can find replacement big valves is on SRM. 

Cheers, Doug

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Re: A10 Big Valves - Rare?
« Reply #1 on: 03.08. 2011 20:46 »
Hi Doug
Draganfly do them and I believe C&D Autos also.
There twice the price of standard ones though (lot more money for an extra 40 thou) £26....

I have two going spare, I had forgotten that I ordered these when I had a big valve head (later sold), consequently I fitted them to a standard head and one of them kissed the piston, could find no damage to the piston or valve but don't know if a bent valve is that easy to detect.

Anyway you probably want new

To be honest I don't think you would notice much in the way of benefit over standard valves unless your going racing, shouldn't think there would be much of a problem using standard valves in it, however wiser heads will comment
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

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Re: A10 Big Valves - Rare?
« Reply #2 on: 03.08. 2011 21:37 »
G'day Doug, welcome to the forum.
                                               The # for the 1.5" valve is 67-0961. Big valve SR heads are like rocking horse poo.
Bill make that 90 thou, and if seat and port are matched I would be supprised if it didn't give at least 1 bhp more.
Cheers
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Offline trevinoz

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Re: A10 Big Valves - Rare?
« Reply #3 on: 03.08. 2011 22:34 »
All 650 alloy heads from 1960 are "big valve" heads!
The 1.5" valve was not standard and is an over size valve.

 Trev.

Offline Woodrocket

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Re: A10 Big Valves - Rare?
« Reply #4 on: 03.08. 2011 22:42 »
Thank you for the help.  I have had a steep learning curve learning about Brit bikes after working with a 1974 KZ400.  

I guess the called big valves are poor value considering the cost and must have been more of a marketing ploy.  Can anyone confirm that the smaller valves will fit on the big valve head?  I believe the part number for the head is 67-1549.  

This is the valve set I have:

http://cgi.ebay.ca/BSA-A7-A10-VALVES-AND-GUIDE-SET-/390326849290?pt=UK_Motorcycle_Parts&hash=item5ae14b0f0a

Cheers,


Doug

Offline trevinoz

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Re: A10 Big Valves - Rare?
« Reply #5 on: 03.08. 2011 22:51 »
Hi Doug,
                 The part number you quoted is the casting number. The part number is 67-1548.
What is the head diameter of the inlet valves?
Do they fit the seats?
When you fit the new guides, you will have to have the seats re-cut.
Do you realise that the set you have bought, if they are as pictured, are not Rocket valves but are Flash or Shooting Star?

  Trev.

Offline Woodrocket

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Re: A10 Big Valves - Rare?
« Reply #6 on: 03.08. 2011 23:11 »
I gathered that and have contacted the vendor and plan to send them back.  I am waiting for my valve spring compressor to arrive and will evaluate them at that time.  I am actually hoping to salvage the existing valves.  There is some surface rust on the valve faces but it should come off.  A rough measurement of the intake valves and it appears that they are 1.5" in diameter.  I jumped in ordering parts without enough homework on the Super Rocket.  Part ordering was much easier with my KZ400!

Offline trevinoz

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Re: A10 Big Valves - Rare?
« Reply #7 on: 03.08. 2011 23:37 »
Someone will give you the original size, it has slipped away at the moment!
Around 1.440", I think.
  Trev.

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Re: A10 Big Valves - Rare?
« Reply #8 on: 04.08. 2011 08:29 »
Beg to differ Musky
This from the Atlantic Green site

Quote
67-1549
This head is for the 1960/63 Super Rocket & 1962/63  Rocket Gold Star.  No visual difference from the 67-1126 head was detected.
The valves for 1960 and up Super Rocket were intake #67-1551 1.455" (37mm?), exhaust #67-967 1.38"(35mm?)
The inlet valve for the Big Valve Super Rocket and Rocket Gold Star was #67-961 @ 1.5"(oh wow).

They also state the ordinary Alloy head can be used with the bigger valves - not in my case
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

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Re: A10 Big Valves - Rare?
« Reply #9 on: 04.08. 2011 08:47 »
Sorry Bill  *respect* I was thinking of the 1.41" valves for '58-'59. My mistake. Sitting in corner with pointy hat.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
Australia
Muskys Plunger A7

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Re: A10 Big Valves - Rare?
« Reply #10 on: 04.08. 2011 09:23 »
Ah no worries Musky I just noticed that difference too, I got the 40 thou from measuring the big valve inlet with what I got from C&D to replace them, I could still have for the year wrong valves in there.
It's coming together nicely though
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

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Re: A10 Big Valves - Rare?
« Reply #11 on: 04.08. 2011 10:38 »
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
Australia
Muskys Plunger A7

Offline iansoady

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Re: A10 Big Valves - Rare?
« Reply #12 on: 04.08. 2011 11:27 »
Sometimes you just have to wonder.....
Ian.
1962 Golden Flash (arrived)
1955 Velo Viper/Venom (departed)
2004 Triumph Tiger 955i (staying)

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Re: A10 Big Valves - Rare?
« Reply #13 on: 04.08. 2011 14:03 »
Ah yes, the long lost development head, somewhere between A65 and rocket three *smiley4*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online chaterlea25

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Re: A10 Big Valves - Rare?
« Reply #14 on: 04.08. 2011 22:12 »
Hi All,
Musky, Wasnt this the head that was for sale from the USA a few weeks ago  ????
Isnt the seller a member here??

To the best of my knowledge and practical experience with A10's
The 67-1549 head is fitted with the 1.450in. dia inlet valves,
The ""Big Valve" head with the 1.50.in valves is overstamped on the last two digits to make it 67-1571

When I built my SR engine, I was given (those were the days *smile*) a 67-1571 head,
It needed a lot of work doing to it, I had it sorted by the "cylinder head shop"
I fitted it with their "Nucleus" valves which are modern "penny on a stick" design, these are 1.450 in.dia
as new seats were fitted. Their view was that the modern design would flow more than the bigger valves would anyway ???? ????
Anyway the result is that it will rev out on the highest gearing that I can fit *smile*

Cheers
John O R

1961 Super Rocket
1963 RGS (ongoing)