One of our members from Portugal, ricardo, has an excellent Blog detailing his Cooper S restoration - http://rsn-mk1.blogspot.com.au/

Ricardo has kindly agreed to let us re-post the following data and photos from his Blog that will be of interest to Ausminiers.

Note: His reference to MK1, MK2, MK3, etc. are the UK designations, not the BMC Australia ones.

MK1 to MK3 twin HS2 inlet manifolds fitted to Minis

This is a listing of the manifolds used in the standard Mini production from 1961 to 1971 that I compiled to reply to another enthusiast. I believe it is worth posting here too.

In 1961 comes out the 997 Cooper with the 12A309 casting manifold. No o-rings for head alignment. Oval mounting flanges for the carburettors.



In very early 1963, or possibly late 1962, the casting was changed to be easily modified for the brand new 1071 Cooper S. From this point, the 12A309 casting had a non-drilled boss for the servo take-off on the balance pipe. These manifolds were fitted to 997 and 998 Coopers until July 1964 when the PCV system was introduced.



All Cooper S's, until the introduction of the PCV system had AEG179 manifolds. These were actually the existing 12A309 casting with the following modifications:

- Flange tabs for studs alignment cut off
- Alignment holes drilled to fit metal o-rings (AEG163 heads have the corresponding recesses)
- Servo boss drilled and tapped for the servo take-off
- Casting number ground off and AEG179 stamped on top of it.



In July 1964 the PCV system was introduced in order to reduce emissions to the open air. Blow-by gases are now sucked into the inlet manifold, controlled by a PCV valve. Rocker cover breather deleted and tappet chest cover with oil separator introduced.
A new take-off was needed in the manifold for the PCV valve, so the 12A309 casting was replaced by the 12A661P and 12A661P2 castings. There are no differences between these two manifolds except for how the number is cast.
998 Coopers had a non-drilled servo take-off and 1004 stamped above the 12A661P or 12A661P2 casting numbers.



Cooper S's had both take-off's drilled and AEG347 stamped above the 12A661P or 12A661P2 casting numbers.



During the MK2 production, the 12A661P casting was dropped. The new casting is AEG573 with squared flanges for the carburettors. These manifolds usually were fitted with one way valves for the servo. Servos already had one way valves fitted on their side (air is sucked from the servo to the manifold creating vacuum inside the servo), so I guess this second valve is redundant, maybe to guarantee efficiency.

Note: The AEG 573 was fitted to the Australian MKII Cooper S and Clubman GT. It was modified to suit 1.5" HS4's for the NSW Police specification.



MK3 production / BMC 1300 range: the 12G2463 was introduced as a remake of the AEG573.
Evident changes:

- AEG573 ground off and 12G2463 stamped below upside down
- A P cast that is not present in previous AEG573 castings
- A smaller hole for smaller one way valves unions
- Cap type of side plugs instead of coin type as used previously



Inside, they're all pretty much the same and not great for performance.

_________________
ex-NSW Police 1970 MK II Cooper S
VMCI #43