One thing I wanted to do with this build was finally get around to fitting the Main Bearing Support Plate. I’d attempted to do this previously but decided against it because it required the Mk1 sump milling. It also required something else but I’d forgotten about that so this time got the sump milled flat whilst I was getting the other block machined.
So, I was brutally refreshed about why it doesn’t fit:
The mk2.5 main bearing support plate (mbsp) is made of significantly thicker metal than the normal mk1/mk2 windage tray. This has ribs pressed into it, presumably for clearance for the crank. The mk2.5 also has space for these ribs. The mk1 sump on which mine is based doesn’t. Grinding clearance into the edge of the sump wasn’t a viable option as it wasn’t thick enough. Instead, I ground down the areas where it clashed on the MBSP until it slotted inside the Mk1 sump nicely. It was silicone to the block and bolted to the main bearing caps.
Then the oil pickup was fitted and the sump went cleanly on.