Once the Bentley was back together, we all held our breath for the first start-up. Counsel and I had done the timing so there was every possibility that would be 180° out! For the first second or two the engine ran perfectly - then the almightiest clattering set up! Switches off!
It was coming from the back of the engine - so it wasn't the fan blade. With the rocker cover off, no pushrods had jumped out of their cups, no springs were broken, and the new valve guide seals were properly in place. After putting the shuftiscope down the plug holes, it looked like there was something odd going on in number 6. We raised the head as far as it would go with the inlet manifold still attached and blocked it up before feeling around on top of the piston. A 3/8th spring washer had somehow found its way into the cylinder during assembly and been smashed into 4 pieces, two of which had embedded themselves into the alloy head. Another piece was floating around on top of the piston and the fourth bit must have gone out with the exhaust. The next start-up confirmed that the problem was solved.
Whilst I was at The Great Collector's, I had a quick look at his RMB to see where the floor levels were and to revisit the possibility of using the Riley front doors in the new project. They would need a bit of reshaping, but it could save me a lot of work - or give me a load of grief!
Back in the workshop, I cut from the RME chassis all the bits that were redundant or needed repositioning - the pedal spindle and bracket for instance. Then I had to admit to myself that the engine mounts I'd created were not really up to snuff. A redesign was in order.
This was the start of the third revision - taking advantage of the top of the chassis rail to provide support.
The Mk 3 also carried the body of the mount across the top rail flange and now, instead of four blots through the side of the chassis, I could get away with one at the top to locate the bracket on the rail and one either side, half way down the back plate.
I'm much happier with this development. It was difficult to make with the problems of compound angles and there was a lot of cutting and fitting, but it's much neater and simpler as a structure and I imagine quite a bit stronger than the previous models. One down, one to go.
Rumbling on in the back of my mind was the addition of a supercharger. It's a subject I know nothing about and the information that is available doesn't seem to answer my questions - one of which is that having worked out what cubic feet per minute (cfm) is required to feed the engine at 5lbs of boost - 252cfm, which of the family of SU carb's has that flow rating? The Morris Six manifold puts the inlet manifold a bit close to the exhaust....
... whereas the Wolseley 6/80 twin carb manifolds could accommodate an induction pipe that went up over the top of the head to cooler air on the other side of the engine. Hmmm.