vxah wrote:ED004EF6-B61D-4D4E-BC5B-41B5738F62D4.png
Hi Rohan, here is my head in case the numbers mean anything?
Not sure what those numbers that appear on the bottom face of many of the heads relate to - probably some sort of batch numbering during the casting (the cast in ones done with dymo tape) and during the machining ( the stamped in ones).
I have had a close look at all my heads and only one, a late Weber head does not have the welch plug in the oil drain chamber. Looking closely I can see a faint indication when the light is at the right angle of where the plug would have normally been. Its not clear if this is a ghost mark left from modification of the casting pattern or where the hole has been welded up at some time. Maybe all the heads without the plug have just been welded up at sometime during maintenance, maybe Lotus changed the casting at some time or welded up the hole instead of fitting a plug during manufacture.
The 1973 Weber head from my Plus 2 has the welch plug so it does not appear to have been a systematic change during manufacture , as much as Lotus ever did anything systematically
cheers
Rohan