I have been a keen reader of the site for some time and now would like some advice on the engine in my 55 Merc.  The block is a 59-60 292 or 312 according to the numbers but the heads are EBU  which are 54 239s,the car runs fine but as this is my first y block its hard to judge. I have recently purchased some ECZ-C  heads and would like to know your thoughts on changing them over thanks Pete