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#484018 - 04/01/13 10:19 pm Identifying a 350 cylinder head  
Joined: Mar 2013
Posts: 9
Sam M, Offline
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Sam M,  Offline
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Joined: Mar 2013
Posts: 9
N. Ireland
Hi,

The cylinder head shown in the pictures below found its way to my door to have a oversize inlet valve guide fitted. I was told that it was believed to be from a B32 and that it was married to a plain ZB34 (i.e. not a GS) bottom end via a 350 barrel (part no. 65-1602) that was fitted with a BB32GS 9:1 scrambles piston (part no. 65-1674). Although the engine is very much a bitsa, the head has a 'whiff' of Goldie about it so I'm hoping some of the members on this board may be able to identify the model of the cylinder head and, ideally, advise on the correct valve part numbers.







The cylinder head has two part numbers which have been partially filed away, 65-1757 is my best guess at the most legible one but I could only find references to B32 heads with part numbers 65-1754 and 65-1756.




When I examined the head it was clear that both valves and the exhaust valve guide were also badly worn and will have to be replaced. The exhaust valve was a disaster waiting to happen, the disc had been built up with weld and then crudely reground.



This didn't inspire much confidence and I am concerned about what else might be politely termed 'non-original'. I know this sort of 'mix and match' assembly could ripple right down the valve train to the cams but identifying the head seems to be a sensible first step in compiling a list of new parts the owner will have to buy.

After trawling through a variety of internet sources I'm pretty sure this is not a B32 head. Assuming the dimensions for B32 valves at http://www.basmotor.se/eng/drivpaket/motor/ventil.html are accurate, the valves and seats in this head, as detailed below, are just too big.

Inlet tract diameter is 1.190" at the flange (1 3/16" nominal?).
Inlet valve seat is 1.500" bore and the exhaust valve seat is 1.466" bore. Both seats look original (and rather pocketed).
The currently fitted valves are:-
Inlet (part no. 65-1842) 1.600 disc dia., 0.309 stem dia. (worn), 4.410 overall length
Exhaust (part no. 65-1644) 1.546 disc dia. (built up with weld), 0.348 stem dia. (worn) 4.180 overall length
Cornucopia (http://www.cornucopia-enterprises.de/catalogue/bsa%20gsv.pdf) list the inlet valve part no. as 1954-55 Gold Star 350 Clubman Road Race trim and the exhaust valve part no. as 1954-55 Gold Star 350 Road trim

The rocker box is of the non-eccentric adjuster design (part no. 65-1506) but I understand that BB series GS engines used this arrangement.

Any help will be much appreciated.

Sam

BSA Gold Star eBay items

BSA Gold Star forum This board is dedicated to BSA Gold Star motorcycles.

#484064 - 04/02/13 2:25 am Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Feb 2011
Posts: 3,353
Boomer Online content
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Boomer  Online Content

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Orygone
It is a BB series head. Can't tell you if it's B32 or B34. Not sure that they made many BB32's.

HTSH

Bill


Boomer
#484067 - 04/02/13 2:27 am Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Feb 2011
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Boomer Online content
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Boomer  Online Content

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Orygone
Oh, by the way, the part numbers you see on the head are casting part numbers and different then the actual book part number. Though most of the time they are one number off of the book part number.

Bill


Boomer
#484079 - 04/02/13 3:21 am Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Sep 2001
Posts: 2,766
Gordo in Comox Offline
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Gordo in Comox  Offline
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Comox BC Canada
Sam: Interesting head. It certainly looks like a BB32GS head

I have a similar head and of course I do not know what specs it originally had.

The cast in numbers are not readable on my head.

The inlet valve opening is 1.5 inches, ex valve opening 1.4 inches, inlet manifold opening 1.1 inches and exhaust pipe opening 1.75 inches. These numbers, although approx, are still a bit different from your numbers.

As far as I can tell it is a BB32GS head. From memory I have 65 1644 and 65 1611 for valves as per the BMS parts list on plate 16 for early GS.

The other possibility is that it could be a late 1952 model ZB32GS with the separate rockerbox that predated the BB. I do not know if the late ZB heads any were different at all from the BB32GS. My 53 parts book shows 65 1644 and 65 1611 for valves.

Gordo


My head







A local BB32GS



Without frequent roadside repairs there is no fun in riding!
#484083 - 04/02/13 3:43 am Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Feb 2012
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Kerry W Offline
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Kerry W  Offline
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Posts: 1,210
Middle East,
Certainly looks like a ZB32 GS (after engine 6001 IIRC) or BB32GS head. Valve sizes sound reasonable, though anything could have happened in the last 60 years -can't recall if the ports/valves were different for scrambles/road/clubmans machines, though probably were, making direct comparisons difficult.

Separate rocker box with non-eccentric adjusters is correct (these cam with the big-fin engines): note that the non-eccentric rocker shaft centre to centre spacing is different ( a touch less IIRC) than the eccentric version. Rockers will be practically (if not exactly, with every wannabe racer having a lightening attempt at them) the same as the B31/B33/M33. Pushrods will have the same ends as the ride-to-work bikes too, though the version of B32 that would have had your head a]had the medium length connecting rod - have never checked, but overall engine height might be less, with shorter pushrods. That said, BSA might have used a taller piston to keep the rest of the parts the same! Anyone know?

What cams are fitted?

Last edited by Kerry W; 04/02/13 3:44 am.

No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
#484190 - 04/02/13 7:05 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Sep 2002
Posts: 7,812
Alex Offline
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Alex  Offline

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Seattle
I thought ZB heads have integral cast rocker boxes. What would be the difference between a BB32 and a BB32GS head? Inlet port size?


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#484195 - 04/02/13 7:34 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Sep 2001
Posts: 2,766
Gordo in Comox Offline
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Gordo in Comox  Offline
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Comox BC Canada
Alex: In the late 1952 model year both ZB Gold Stars changed from the one piece head to the separate rockerbox head. The 500cc the serial numbers jumped from the 4000 series to the 5000 series for this change. About 175 of these were made.

The 350cc model numbers jumped to a 6000 series. They started in the 4000 series in 52 so maybe they were already in the 5000 series when the change was made. I do not know how many 350 machines were built in the 6000 series. Both of these changes are shown as going from sand casting to die casting in the serial number lists.

For the 1953 model year they became BB engines and the numbers started all over again at 101.

As for differences I think the ports were the big differences. I know the Clipper BB34A heads have a different number on them.

Gordo


Without frequent roadside repairs there is no fun in riding!
#484200 - 04/02/13 7:41 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Sep 2002
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Alex Offline
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Alex  Offline

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Seattle
Thanks Gordo. Didn't know about the '52 ZB heads.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#484202 - 04/02/13 7:47 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Sep 2001
Posts: 2,766
Gordo in Comox Offline
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Gordo in Comox  Offline
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Posts: 2,766
Comox BC Canada
Alex:

Here is a shot of a 52 ZB Clubman TT machine with separate rockerbox head and still in the plunger frame. Shot is from the Don Morley Classic Motorcycles BSA book.



Without frequent roadside repairs there is no fun in riding!
#484443 - 04/04/13 8:56 pm Re: Identifying a 350 cylinder head [Re: Gordo in Comox]  
Joined: Mar 2013
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Sam M, Offline
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Sam M,  Offline
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Joined: Mar 2013
Posts: 9
N. Ireland
Folks,

Many thanks for your answers to my questions. It helps greatly to know that I'm looking for Goldie rather than B32 valves. I'll contact Phil Pearson to see if he can supply the valves mentioned.

Kerry, in answer to your question, I don't know what cams are fitted. The engine is a fitted to a grass tracker that will probably only be taken out for the odd canter and the owner has a limited budget so the guidance amounted to "if it isn't obviously broken don't even look at it".

Sam

#484831 - 04/07/13 5:22 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Sep 2001
Posts: 2,766
Gordo in Comox Offline
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Gordo in Comox  Offline
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Posts: 2,766
Comox BC Canada
Sam: If you look at Magnetoman's thread on head numbers your 65 1757 cast in numbered head would have originally been a trials BB32 head if the system of +1 in the numbers holds true.

Gordo


Without frequent roadside repairs there is no fun in riding!
#484864 - 04/07/13 9:42 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Mar 2013
Posts: 9
Sam M, Offline
BritBike Forum member
Sam M,  Offline
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Joined: Mar 2013
Posts: 9
N. Ireland
Gordo,

Thanks for the heads up. I hadn't spotted that post and it's good stuff!

Sam

#486231 - 04/17/13 9:41 pm Re: Identifying a 350 cylinder head [Re: Sam M,]  
Joined: Mar 2013
Posts: 9
Sam M, Offline
BritBike Forum member
Sam M,  Offline
BritBike Forum member

Joined: Mar 2013
Posts: 9
N. Ireland
Folks,

My search for an exhaust valve for this head has hit a snag. In attempting to source a 65-1644 exhaust valve I contacted Roy Shearwood. Although he couldn't supply this valve, Roy very helpfully told me that BB32 exhaust valves had a disc diameter of only 1.475". Given that this head has an exhaust seat bore of 1.466", such a valve just isn't big enough and it begins to explain why the 65-1644 originally fitted to the head had been built up with weld.

For what it's worth, the exhaust valve seat and port surface/profile look original to my eye and the degree of valve recession is similar to that on the inlet valve. I'm inclined to believe this is how it left the factory.





To achieve 50 thou overlap on the seat would require a valve with a 1.566 disc dia. Can anyone suggest a valve that would fit this head?

Sam


Moderated by  Rich B 


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