Author Topic: Twin carb head  (Read 9993 times)

Offline chaterlea25

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Twin carb head
« on: 05.10. 2009 23:01 »
HI All,
On Ebay Australia a guy is offering one of the Alloy twin carb heads 67-1106  
Ebay number 190339038713
He's also selling a heap of other spares
Nothing top do with me! etc

Regards
JOhn O R
1961 Super Rocket
1963 RGS (ongoing)

Offline LJ.

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Re: Twin carb head
« Reply #1 on: 06.10. 2009 00:55 »
Gosh that is a rarity wonder what that'll go for?
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: Twin carb head
« Reply #2 on: 06.10. 2009 03:49 »
Trevinoz can probably clear this up but as far as I know there is no such thing as a twin carb head for these models, this is a standard early alloy head missing the intake manifold. The later heads had the intake manifold cast as part of the head.

Offline trevinoz

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Re: Twin carb head
« Reply #3 on: 06.10. 2009 22:15 »
Brian,
         In the U.S this head was offered with factory adapters as part of the "speed kit".
I have attached a scan of the brochure.
The heads originally fitted to the 1954-55 models have a date code cast in them. Later ones don't.
The "manifolds" have a BSA part number.
Trev.

Offline trevinoz

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Re: Twin carb head
« Reply #4 on: 06.10. 2009 22:19 »
Further to my post, one of these recently sold on U.S. e-bay for $1725.00, without manifolds!
Trev.

Offline RichardL

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Re: Twin carb head
« Reply #5 on: 06.10. 2009 22:57 »
I guess that means I can't get three at $158.05/ea. ;) *smiley4*
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Brian

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Re: Twin carb head
« Reply #6 on: 06.10. 2009 23:40 »
Lets see if I have got this right.

The actual cylinder head in the kit is the standard BSA item with the detachable manifold as used from 54' to 56'.

If you have a Flash with cast iron head then you would need the complete kit including head but if you already had a 54' to 56' Road Rocket and wanted twin carbies then you would only need the manifolds and carbies.

If you had a Late 56' onwards Road Rocket then once again you would need the complete kit.

I cant understand why anyone would pay US $1725 for a head, in the ad the whole kit including carbies etc is only $158.05 !


Offline trevinoz

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Re: Twin carb head
« Reply #7 on: 07.10. 2009 04:18 »
Brian,
          that ad is from 1964.
Trev.

Online Brian

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Re: Twin carb head
« Reply #8 on: 07.10. 2009 05:02 »
Should have bought a few kits and kept them as investments, damn site better than my superannuation ! Mind you in 1964 I was only 8 so I would have had to save up my rabbit trapping money for quite some time to get $158. Wasnt long after that I needed my money to put fuel in and keep the spare parts up to my Bantam. Been riding BSA's all my life, you would think I would have learnt by now !!!!!!

Offline trevinoz

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Re: Twin carb head
« Reply #9 on: 07.10. 2009 23:09 »
Brian,
         here's another one from an earlier time.
Trev.

Online Brian

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Re: Twin carb head
« Reply #10 on: 08.10. 2009 00:04 »
Good stuff Trev, I notice they mention the 358 camshaft. I've never come across one of these.

Offline LJ.

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Re: Twin carb head
« Reply #11 on: 08.10. 2009 00:45 »
surprising to see the 276 pre monobloc carbs on a 1956 - 60 twin port head!
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

Offline MikeN

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Re: Twin carb head
« Reply #12 on: 08.10. 2009 12:26 »
Ive never really understood how fitting twin carbs improves performance (although im sure it does).On a single carb engine ,once every revolution, one of the cylinders takes its turn to draw in fuel/air mixture through the carb.On a twin carb engine each clylinder breathes through its own carb every other rev which is the same thing.So why is that better?
  I could understand if both cylinders were trying to draw mixture through the carb at the same time.But they dont.
  I can only think that on the twin carb the inlet tract takes a more direct and less convoluted  path  than on the single so its streamlining the flow.Is that it?
Mike

Offline rocket man

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Re: Twin carb head
« Reply #13 on: 10.10. 2009 11:12 »
i think a single carb is better its easier to set up

Offline chaterlea25

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Re: Twin carb head
« Reply #14 on: 12.10. 2009 21:18 »
Hi All
Well there were no bids on the head!!!!!!!
Nows the time to contact the seller and get a bargain *ex* *ex* *ex* *smile*
Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)