M codes

[Aaron Britcher <abritcher@ezinet.com.au>]

Howdy all. No I have never seen M codes printed on the id tags of any 
Type 3's and I have seen lots! However I have one M code stamped on my 
1964 1500 'S' engine which is the M249 option which to non 'S' owners 
means that the engine was built after august 1964 and sent to an export 
country. Why M249 and what does it mean? M249 signifies that the engine 
has flat crown 83mm pistons as opposed to the domed crown units fitted 
to all 'S' motors previously and all those sold in non export countries. 
Everything else reamins the same with the only obvious change being the 
compression ratio dropping from 8.5:1 to 7.8:1 from memory. The bhp 
drops from 66bhp to about 63.5hp which isn't much of a drop but it 
should allow the engine to live comfortably on the fuel of the time. 
Germany had no idea what fuel oktane ratings were outside of Germany and 
hence they made this option mandatory on export engines after August 
1964. The option is stamped into an aluminium plate which is affixed to 
the breather tower on the engine. At the same time all 'S' engines 
recieved a new distributor, the 311 905 205D in place of the ZVJCU4R3 
which was a combo vacuum/mech advance dizzy. The carbs were also 
modified and if anybody wants that info I will put it up later when I 
have access to my files. If you want I can put my list of M codes on the 
list for all to see. I can't remeber how many I have documented but I 
must have close to 2 pages worth, maybe more. 

Question for the Type 3 guru's that know their M codes: What does the 
M265 option signify? 


Aaron (If no one answers by about friday/saturday I will tell you the 
answer).