Twin carb head

[chaterlea25]

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

[LJ.]

Gosh that is a rarity wonder what that'll go for?

[Brian]

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.

[trevinoz]

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.

[trevinoz]

Further to my post, one of these recently sold on U.S. e-bay for $1725.00, without manifolds!
Trev.

[RichardL]

I guess that means I can't get three at $158.05/ea.

[Brian]

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 !

[trevinoz]

Brian,
          that ad is from 1964.
Trev.

[Brian]

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 !!!!!!

[trevinoz]

Brian,
         here's another one from an earlier time.
Trev.

[Brian]

Good stuff Trev, I notice they mention the 358 camshaft. I've never come across one of these.

[LJ.]

surprising to see the 276 pre monobloc carbs on a 1956 - 60 twin port head!

[MikeN]

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

[rocket man]

i think a single carb is better its easier to set up

[chaterlea25]

Hi All
Well there were no bids on the head!!!!!!!
Nows the time to contact the seller and get a bargain
Cheers
John O R