For the
unwary, there are two lengths of 'short' nose cones fitted to Box Saloons and
presumably other contemporary Austin Seven models (1931-1934).
The RN
Saloon had a nose cone with an overall length of 7¼", the later 4 speed gearbox
RN and the RP Saloons had a 6½" nose cone. The difference in length is ¾". To be
accurate the A7 Source Book states the difference is 13/16", but all items I've
measured come out to ¾".
The
starting handle shaft was also a different length by ¾", that is shaft lengths
of 77/8"
and 71/8" respectively.
The
difference is because the crankcase introduced with the 4 speed gearbox sat
further forward in the chassis (starter motor on offside of engine). The
crankcase feet were repositioned further back on the moulding, so the chassis
holes remained in the same position, also the fan spindle, starting handle shaft
and it's housing were shortened by ¾". Some references say the radiator was
also moved forward, but this does not appear to be correct because you can swap
bonnets between the two models without any fitting problems.
On the RN
Saloon the length of the fan pulley from the fan belt groove to the rear of the
fan casting is 1" and the clearance between the fan and radiator is 5/8". On the
RP Saloon, the dimensions are ½" and ⅜"
respectively. That is ¾" difference.
Some of our
members have bought the RP nose cone to fit on a RN and wondered why it did not
protrude out of the Radiator shell, others with RP's have wondered why their
nose cone (RN) has stuck out so far, especially if they have tried to use the
(RP) shorter starting handle shaft.
The 6½" RP
nose cone has a moulding number of 1A559, RN moulding number is 1A459.
This item
has arisen through correspondence between myself, our Editor, Malcolm Watts and
Dave Mann of the RN Register. Any errors are all mine.
This article, written by
Sandy Croall, originally appeared in CA7C Seven Focus
April 2004 pp 6-7.
Some of our
members have bought the RP nose cone to fit on a RN and wondered why it did not
protrude out of the Radiator shell, others with RP's have wondered why their
nose cone (RN) has stuck out so far, especially if they have tried to use the
(RP) shorter starting handle shaft.