so why have i got three variations on a theme, all supposedly for M20's...
two are similar, but one has a fixed pipe about 3" long that goes into the crankcase.
the other has a smaller outlet dia, ( the one that fixes to the breather pipe )
all three fit the crankcase spigot.
all three appear to breathe both ways, so why is there a fibre washer in the middle ?
email (option): chris.astinbarker@btinternet.com
Hi Chris...WDM20s have the breather screwed into the crankcase below the barrel on the drive side and have the smaller fitting on the 'output' end with the small nut, small diameter pipe and no pipe on the 'inner end'. Post 47 M Series models had the breather relocated to the timing cover and in this location it had the larger diameter 'output' fitting with a matching larger nut and pipe and the fixed pipe inside the timing cover..
The 'fixed' pipe on the inner end can either have an open end (the early type) or a closed end...where the pipe was crimped flat and a hole was drilled through the side (the later type).
The breather works to both evacuate air from the crankcase on the downward stroke of the piston and to partially seal the crankcase (causing a partial vacuum) on the upward stroke of the piston.
So, the little Tufnol disc should be free to 'float' within the breather fitting, being blown off its (flat) 'seat' by the pressure of air being forced from the crankcase as the piston moves downwards and being sucked back onto its seat to seal off the pipe when the piston is moving upwards again. It is in fact a one way 'valve'...Ian
email (option): ian@wright52.plus.com
I'll buy it off you Chris...or swap it for the type you want (if you want one)....Ian
email (option): ian@wright52.plus.com
its yours...i'll bring it up next time . remind me ! being a pensioner my memory isn't what it .....what ?
email (option): chris.astinbarker@btinternet.com