Sherman M4A4 Restoration Part 5: Rebuild of the Blocks

Starting this had made me realise how many gaps there are in my photo record. All the pictures are on film and it would be much easier to do on digital. Having said that, you still need to take the pictures so forgive me if there are areas that are a bit sparse on the visual front.

Having seperated the blocks from the centre case, they became like any other engine rebuild albeit multiplied by five.

The main problem was with the general condition. As I mentioned before, some pistons slipped out with no effort but that was far from the norm. I could free them by pressing downwards but they had to come out from the top so much soaking and gentle(!) persuasion eventually had them all out.  The crank was easy but the camshaft was another matter. The valves were all stuck, some very stuck and so I had to make a tool to pry them away from the followers to allow rotation of the cam. This allowed me to remove the collets and then the valves.

Eventually, all of them were stripped and I had to pick five serviceable blocks for rebuild. Out of the ten, only five were not obviously cracked so it was a lucky thing.

Unfortunately most required re-sleeving and new valve seats. Together with pistons, this was going to cost a small fortune.

At this point, I had a bit of luck…… Whilst speaking to Jaap Rietveld, it became apparent that some ‘odd Dodge blocks’ he had may well be multibank. More to the point, there were six of them, they were nos and for sale! A few days later I was the proud owner of this lot.

They came with mostly new studs, the lengths of which change to suit the position of the engine, 21 nos pistons, water tubes and cam bearings.

This lucky find made a huge difference if only to my enthusiasm! I could have used my blocks but this saved money and time and I knew I had brand new blocks with no cracks and clear water passages.

I managed to salvage a full set of internals with the bulk coming from my tanks engine with just a camshaft coming from the other. There was a lot of cleaning to be done though….

The new blocks were of an intermediate production standard with the 10 bolt valve covers, the early engines only having six bolts and standard valve guides. The later sodium filled exhaust valves requiring a different guide to suit the fatter stems.

I built up all five engines, including hand lapping 60 valves, and here they can be seen after painting. They are numbered 1 to 5 from left to right and are installed on the power unit numbered anti-clockwise starting from the top block. It’s possible to see the different manifolds, timing gear covers and water fittings in the heads.

You can also see the old blocks I didn’t use in the background.

Part 6 – putting all the blocks together = one multibank