BSA A-7 & A-10 Dual Port Heads/Manifolds
& Single Port Heads
David Comeau
2 Dec 2001- revised 25 Feb 2007
Please note-I have used the casting pn and not the BSA assigned assembly
pn
Please visit fellow BSA enthusiast Myles Raymond's website for additional information on A-10 dual port heads.
http://www.restorenik.com
67-1102 for A-7
This is the original 1954/55 BSA dual port A-7 (66mm) head. This was in
production when a BSA A-7 won the 1954 Daytona 200 race. The valves were
intake #67-531-1.30", exhaust #67-532-1.30". The ports are 24mm in diameter.
Additional porting work is needed to make them flow.
The production A-7s came, as shown below, with the 67-1112 single
carb manifold.
67-1102/6 for A-10
This head is a head originally conceived for the 66mm bore A-7, but at
BSA it was finish manufactured for the 1954-1955 A-10 Road Rocket, bore size 70mm, additionally
it was metal stamped with a "6" to obliterate the original cast
"2". Note the positioning of the earlier "AM" casting marker. Still
with 24mm ports.
The valves would have been the same as the later 67-1106 head,
1958/59 super rocket, intake #67-968-1.41", exhaust #67-967-1.38".
I will be putting in the RGS/competion intake valves #67-961 1.5" into
this head. The billet manifolds (see below) I designed were to allow 30mm
concentrics to used on this head.
67-1106 for A-10
Below is probably the last version of the dual port A-10 head,
67-1106. It has a "K54 AM" casting. Also shown are the factory
dual carb manifolds. Probably works better on the computer screen than
it does on the dyno....
The valves were 1958/59 super rocket, intake #67-968-1.41", exhaust
#67-967-1.38".
The right manifold to head stud holes had to be welded and redrilled
since the port matching was very bad. The port matching on the left
one was as original. The carb bolt hole mounting angle on the right manifold
is cocked a little. Only partially the result of the mount hole repair,
they were off angle before the repair also.
