Originally Posted by Mr Davis
Hmm... I guess I'm just seeing ghosts!

Maybe if we could work out how the serials work on these machines we could find a way to date it that way?

It looks like the letter partly visible in the serial number pic, after the engine model, is a date code. See http://www.oldengine.org/members/diesel/EngineDating/JAPDate.htm

But the codes were 're-used', so the model number would determine which 'date block' is applicable.

And from another forum, http://www.internalfire.com/phpbb/phpBB3/viewtopic.php?f=1&t=3195
Quote
Author: theJAPManNZ [ Mon Feb 20, 2012 8:15 pm ]
Post subject: Re: Identifying stationary Engines.- Complete Novice
For the JAP, the serial number will be on the top of the crankcase, next to the joint with the cylinder block, on the carburettor side, if it isn't OHV. As far as I know, they were made in 3 blocks, with part of the serial number as the date code.

the serial number is made up of; model no./year code/serial no./customer number

J A Prestwich Engine Dating - Block 1 - 1920 to 1939
Letter Year Letter Year P 1920 W 1930 N 1921 H 1931 E 1922 Y 1932 U 1923 Z 1933 M 1924 D 1934 A 1925 R 1935 T 1926 V 1936 I 1927 F 1937 C 1928 O 1938 S 1929 G 1939
J A Prestwich Engine Dating - Block 2 - 1940 to 1959
P 1940 W 1950 N 1941 H 1951 E 1942 Y 1952 U 1943 Z 1953 M 1944 D 1954 A 1945 R 1955 T 1946 V 1956 I 1947 F 1957 C 1948 O 1958 S 1949 G 1959
J A Prestwich Engine Dating - Block 3 - Post 1959
A 1960 C 1962 B 1961 D 1963

There is an engine manual for the 4/3 available for download [registration required, but rego is free] at http://www.internalfire.com/index.php?loadf=93&sid=d04848e292f0b69a2c329f3bfbe386a4

Looks to be a lot of useful docos for other engine makes there, too.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."