1962 88SS cylinder head

Which head do you have, Jonathan? The first 100 or so 88SS had the earlier head, not the 'downdraft head ' as fitted to the 659SS. If you have that, there is no great reason to change It, especially if it is running well. Can you post a picture, including carbs and manifold arrangement? It might well be original.

ps.The route to having a basket case is lined with people with ambitious intent but not having the skills to complete the job without the assistance of some else whom they don't actually know...

Incidentally, there is an Atlas head on ebay at present but it won't fit because the main bolt spacing is a bit wider. So if you pay what seems like a great deal of money, you need to be certain it is what you need. Does it have correct bolt spacing? Does it have valves and guides in good condition, or will they be another money pit? Is it for spigotted barrels (as yours should be)? I very much doubt if you will be able to sell it on for anywhere near that kind of money. Also I doubt if it will much change the value if your bike.

Others might have other views, but unless yours has real issues, I'd leave well alone.

Choosing a replacement Cylinder heads for a Dominator is one of those areas where walking across a minefield blindfolded would be a better option.

Any of them manufactured between 1949 and 1960 will fit on a set of 88 barrels. This includes all the iron and alloy versions. But........the early spigoted 650SS head can also be bolted in place.

The big difference with the SS head being it was made to take twin carburettors and splayed exhausts. The latter point frequently catching new owners out.

I hope for the 1600 euros being asked that this is a brand new head, fully kitted and ready to fit. Current prices, in the UK, for a reasonable condition 650SS head range between £250 and £400 depending whether a dealer or private sale.

There were not too many 88SS bikes sold with the spigotless head and barrel combination. You mention your bike as having a normal head in which case it probably has a spigoted barrel. So if you still want to go down fitting an SS cylinder head look out for one with 22707 on the top near the inlet rocker cover.

The attachments show pre-1958 88/99 cylinder heads (left), 1958 to 61 88/99 heads (centre) and a proper 650SS head.

Sorry if it seemed I was insulting your friend, but I did not know the head was already off. But from your reply you seem to know the answer about whether the job is doable...Phil know far more about Dommie heads than I. But the fact is there are lots of different ones out there, some of which share the same casting number.

But your head certainly appears to be the late type with larger cooling fins alongside the wider splayed exhaust ports.  The only thing is that someone has changed the downdraft inlet ports to horizontal ones.  Strange!  I wonder if it is some rare half-way design?

I think that is a standard 88/99 head that has had   twin carb   mounts welded on (as you noted) .Provided it has not been opened out to big  it will most likely perform  as well as a proper DD head.  If you decide to go for a proper DD head  you will also need new pipes as the port splay is wider.   If you continue with your current head you may need to shorten the pushrods to restore the correct rocker action.Interesting that it is stamped SS on the underside!.

Jonathan.......that is a really good looking modification. In fact, one of the best I have ever seen when compared to similar conversions. Generally there are lumps of loose weld all over the place making this change of carb mounting look very tatty.

One of the drawbacks of such drastic cosmetic work is that the excessive heating can cause distortion. Which is probably why the head needed skimming. Keep an eye on the gasket face area as there may still be tension within the head which will take time to be released. A sign of this will be if the head gasket starts leaking badly.

The 88SS & 99SS engines both used the fatter SS pushrods but these were the same length as the pre-1960 thinner versions. The attachment shows the variations of pushrods.

I would warm it up to 200 degrees in an oven and cycle it to cool down a few times, then check with engineers blue on a surface plate to see if it still flat.

The SS stamping on the underside looks exactly the same as my 99SS non DD head, so most probably yours started life as a 88SS or 99SS non DD head, maybe in 1961.

As the head is probably the only one with that particular conversion (and done so well!), It will be of  special  interest to the Norton "experts"  every time you meet up with other members. There are plenty of standard bikes that barely warrant a glance ,so you could be "one up" with little effort. I would keep it , How many other twin carb non splayed ,non downdraught Nortons exist?.I can only think of one ,a very special 500cc Nomad.It might also be worth checking the build date and original colours ,a 61 could have been 2 tone  Green and Dove grey.Super rare.

Try looking this over and see if you can figure out what you are trying to accomplish:

http://atlanticgreen.com/nhth.htm

A 88SS is more than the head. The barrels and push rods are different to accomodate the SS cam. Therefore it may be possible the prep work has been done on a 61 88SS to take the DD head .

 The DD head is the same P/N for 500 and 650 and are both 28.5mm port bore. Early heads were 25mm unless DIY modified.

A modified 88SS/136 head (61 88SS/99SS)is unlikely to flow like a real S650/136  (62 88SS/650SS) head. Though I have seen lots of DIY attempts.

Good Luck!

It seems likely that the head is original to the bike but with the modified mountings. I can't see what the advantage would be to do this mod other than to eliminate the slightly clumsy looking bolt on splayed manifold. Certainly the splayed carb 88SS was road tested and found to be very fast and later tests did not show the DD head to be of any real improvement despite its theoretical better breathing.Perhaps this mod allowed the fitting of the later air filter box or trumpets?. Air filters on the splayed carbs would get in the riders way. An interesting puzzle.