After about '59 or '60, Triumph started marking their 650 heads as to the year model or possibly they would mark a head as 65 for a '66 model.
Prior to that, they had a part number cast into their heads. I have several pre unit heads that have part numbers cast into them that do not match any listed part numbers published in their parts books.
I do have a nice head with the part number E3925 cast into it. The closest part number listed is E3924.
Did Triumph cast the wrong ( but close) numbers in their heads?
Next problem that bit me are the valve springs. They have the correct 2.03 free length, but installed, they look like they will coil bind big time.
The springs have a 6 1/2 coils per spring that are .1445 thick.
Can anyone advise me if these numbers are correct?
These springs are supposedly made in the UK