Identification engine type

[Geoff Dowdle]

Noot,

N312400 is the block casting number .
This casting was used from 1951 - 1954 in the following engines that I and others have sighted & recorded (but I can not say all of these block in the period were N312400).

Late 85C without the heat exchange bulge fitted to 401
100A and AB2 fitted to 403
100B fitted to 404
early 100B2 fitted to early 405
probably some 100C & C2

You mentioned "FSN" please confirm is that correct or is it "FNS"

FNS engines were fitted to Frazer Nash cars from late 1948 to early 1953 and more than likely used block castings N312400 in most of them but I have no record of that .
I suggest you post a few photos of the exhaust side of the block & FSN stamping and the top , bottom and distributor side of the head . Most Bristol heads have a part number and date stamped in the bottom face .

Geoff