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.

[manosound]

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

[trevinoz]

John,
            I think this is the second time this head has gone through and not sold. Not worth that sort of money anyway.

Brian,
        the 358 camshaft timing figures are 57 - 77 - 90 - 51.  I can't remember where I got this info from or if it is accurate.
A mate had one in the early 60's and said it was not much good on the road so he quickly put the 357 back in.
Trev.

[chaterlea25]

Hi Trevinoz,
I believe parts down under go for less money than in the Northern hemisphere
Fleabay has wrecked the autojumble scene here, Ebay dealers go around and buy up anything
to resell on the net.
For example recently someone paid £511 for this Lucas King of the road mirror on Ebay. no 160364886152
Sheer maddness
What about £104 for a BSA propstand (of course advertised as RGS or Gold Star)  no.180413250175
Maybe you should start exporting stuff north

Regards
John O R

[rocket man]

your right the best stuff is going fast at least there in demand
so my bike is a good investment as there going up all the time

[muskrat]

G'day all,
            here is mine. A7 with A 10 valves, ported for 30mm carbs & through bolted.
Cheers

[rocket man]

that looks a great mod mate well done