Throttle Body Numbering
CP - No DD Number
These are the earliest production throttle bodies fitted to TR5s and had no DD number on the casting, and no reinforcing around where the balance pipes fit.
CP - DD1 Early
DD1 designation in casting but still with no reinforcing around where either of the balance pipes fit.
CP - DD1 Later
Still designated as DD1 but with reinforcing for the left / bulkhead side balance pipe only.
CP - 1DD
Reinforcing is now provided where both balance pipes are fitted. Note 1DDs are the crossover point and were fitted to late TR5s and early TR6s.
CP - DD2 Onwards
Reinforcing over both balance pipe entry points, minor detail changes to profile of keep plate fixing, part number moved from the upper face to webbing between inlet ports on the underside. Butterfly spindle levers were soldered on and no longer replaceable.
CP - Summary
All CP throttle bodies are interchangeable apart from the earliest type that have no DD number. Whilst they all have the same 1.75" diameter butterflies, the port between the butterfly and the mating face tapers more than the later throttle bodies and as such the port is narrower where it attaches to the head.
CR - All
CR throttle bodies share the same DD1 - 6 numbering system but are different to CP throttle bodies in a number of ways:
they have dual balance pipes
the idle air valve is fitted in the additional row of balance pipes near the cylinder head
the butterfly spindles are larger diameter
CR - All cont.
the butterflies are thinner
butterflies are fixed with countersunk screws
all spindles are interconnected and operated by a single throttle linkage rod on the front throttle body
the inlet ports are narrowed where they fit to the head