More carb manifold woes 1962 Dommie 99

The change came with the  new head  which was introduced   in 1959 . This head has the milled off fins between the rocker end fixings ,a raised compression and bigger valves. Lots of them around. 

Hi David, Yes ,also very common in the UK as it was fitted to the basic 88 ,99 and 88,99DLs  as well as the early 88and 99SS  for around 3-4 years.  Probably not so very common in the USA. With valve sizes and  compression the same as the Downdraught head  it can perform very well with twin carbs and no problem with fuel flooding or cracking.I was surprised they did not use this head on the 650 std and 650 DL as it would have fitted into the tinware without the need for a special new single carb manifold.

Further to Peter's mail. The holes in the manifolds were made oval by the factory. Two examples here are very clearly oval. But how nuts would have put on studs at 1.5" spacing is anyone's guess.

I guess none of the manifolds are factory milled with oval holes if they came to the US? Which head would they match?

All four of mine are clearly round holes only. Since they are SO common there in the UK, manifold confusion may be rampant and therefore a need for a popular publicized bodge?

I should ask here too, did the factory make dual carb splayed manifolds for the early 1-1/4 heads?

I get no response other places...no one knows?

I fitted a factory splayed manifold to my 60  big valve  88   and mounted a pair of monos from a 650 SS,did not change anything else and it would  drag race alongside  a 99SS  up to 90 mph  .No oval holes in the manifolds anywhere.  That looks like a bodge to fit wrong parts .

All I know about these is that my Dommie's PO had a 99SS and 88SS for sale and I bought the 88. He threw in some spares, some of which I layer realised were for the 99. These two manifolds were in. One seems to be for standard single carb, and the other splayed to mount twin carbs. Both have the same oval holes. He was a very competent machinist so he could have done it.  I've no idea of originality, but there must have been a reason common to both of these and, I suppose, Pete's. Did the very early heads have studs at 1.5"? It would make sense for Norton to carry on using the same parts.  Ps..bored and don't want to work in the shed...it's snowing...

Incidentally...I've just noticed the external rubber balance tubes fitted to the later bikes was drilled in to the splayed manifold. 

Hi David  ,  I think the splayed manifold you have was for the earlier head   and has been worked on to fit the later one  .  Its what we did back then. 

The splayed one has 1" bores.

The single has 15/16 in and 1+1/8 out!