Proper 1961 Dominator 99 standard head

If the 59 head was smooth alloy above the plugs/between rocker plates then itts the wrong head. If the new head has the milled off ribbing at that place its the right one.Even if you had an SS head that fits I would count it as right enough!.

If the 59 head was smooth alloy above the plugs/between rocker plates then itts the wrong head. If the new head has the milled off ribbing at that place its the right one.Even if you had an SS head that fits I would count it as right enough!.

The 1961 head was fitted to 88/99's from some point in 1959 onwards .It had bigger valves ,ports and raised the compression by about 1 .It should match the barrel .Don't know if the pipe angle changed.

Peter......For reasons that only the Norton factory can answer there were 2 versions of the 22707 head about in 1961. A version for the Standard 1960/61 88 and 99 models plus the new SS head for the 650 bikes which had just arrived. They are all interchangeable within the 500cc, 600cc and 650cc range of bikes except in the areas of exhausts, carburettor mountings, valve springs and to some extent pushrods. The SS head had very widely splayed exhausts at an included angle of about 80*. This often catches people out when restoring a bike.

The 22707 cylinder head that you decribe appears to be correct for your bike. Attached pictures should confirm. The suffix letter was just to indicate which casting mould the head was produced in. The valves are the same size as on the SS head but need the older, thinner and longer 2" springs of the early heads.

The chunks of any Norton Twin cylinder head that need careful checking are any threaded holes. Foremost beingthe exhausts ports and plug holes. Don't forget the 3 underside 3/8" head mounting studs. Next look at the valve seats in case they are badly worn and recessed. Also, in this region, check for cracking between the plug hole and valve seats.

Peter......For reasons that only the Norton factory can answer there were 2 versions of the 22707 head about in 1961. A version for the Standard 1960/61 88 and 99 models plus the new SS head for the 650 bikes which had just arrived. They are all interchangeable within the 500cc, 600cc and 650cc range of bikes except in the areas of exhausts, carburettor mountings, valve springs and to some extent pushrods. The SS head had very widely splayed exhausts at an included angle of about 80*. This often catches people out when restoring a bike.

The 22707 cylinder head that you decribe appears to be correct for your bike. Attached pictures should confirm. The suffix letter was just to indicate which casting mould the head was produced in. The valves are the same size as on the SS head but need the older, thinner and longer 2" springs of the early heads.

The chunks of any Norton Twin cylinder head that need careful checking are any threaded holes. Foremost beingthe exhausts ports and plug holes. Don't forget the 3 underside 3/8" head mounting studs. Next look at the valve seats in case they are badly worn and recessed. Also, in this region, check for cracking between the plug hole and valve seats.

Well the first Down draft head was Not fitted to the 650SS , Nor was the Cam and Its valve train , or the Barrels and Crank and Crankcases,

The First 650 Machine built out of Bracebridge street workshop , from the 7th of November 1960, was the 650twin Know has The Norton Manxman for Export Only, the Birtish got a revamped models 88/99 in Sport mode, from April 1961, knowen has the the 88 and 99 Sports Speicals ,then to the end of 1961 the British public got too see the 650SS in Blue, at First, and then in Norton Standard colours Black and Silvers so it cost less to compete with the Triumph 650 twins Yours Anna J

Peter, the head you illustrated looks exactly correct for your 99. I would not expect it to be fitted with the SS downdraught head - the one with the horizontal inlet studs and splayed exhausts.

Gordon.