The engine was tilted on its side, during the sump on-and-off routines as needed for the block fitting stage. The engine was supported by a big green bag and stuffed with rags and the odd strategic lump of wood, to enable the sump to be removed. Then the connecting rods were drawn down, bearing caps fitted, and nuts put on, but not fully tightened at this stage. The sump was once more attached and the engine sat back upright again, after which all the block holding down nuts were fitted. The engine was turned over by hand a few times to ensure that there were no foul-ups and also to help things to line up, before finally tightening down the block. With the block on properly, the engine was laid over on to its side again and the sump removed to torque up all the big end nuts. Finally, the sump could be fitted for the last time, with a gasket between the mating faces. The engine was at this stage when this picture was taken. Big end caps are all in place and torqued up, and oil pipes and suction filter have also been bolted into position.

The next step was to fit the sump. Any studs removed to facilitate the sump on-and-off shuffle were replaced at this stage to allow even tightening of the sump on to the crankcase. With this done, the stage of replacing the cylinder head had been reached. At this stage it might appear that the engine was now well on its way to completion, but in fact the job was only about half complete. However, to use part of a Churchill quotation, "...the end of the beginning" stage had been reached.

The cylinder head had been stripped bare, in order to address the issue of worn roller bearing cam followers. While these were being dealt with, the cylinder head itself was cleaned up and prepared for valve grinding. Both the head and the block had been lightly machined to ensure perfect flatness at an early stage in the engine reconditioning project. All the valves were ground and fitted into the head, following which it sat on the bench ready to be fitted. Before fitting the head, new holding down studs, and some solid copper gaskets had been commissioned. One of these was annealed, using two butane gas torches and a pile of bricks to reduce heat loss, to ensure satisfactory sealing of gas, water and oil in their respective active compartments. Then with a liberal dose of "Wellseal" the head was sat on top of the block. One of the curious aspects of the use of downward facing studs to attach the head to the block was apparent when fitting the head; there are of course no head studs to locate the gasket. So, fitting was a case of trying to line up the stud holes in the gasket carefully with the holes in the block, and endeavouring not to dislodge the gasket with one or more studs as the head was lowered into place.

The head was tightened down progressively using the mutilated ring spanner. A hollow pipe was slipped over the sawn-off end of the spanner, to make a wrench effectively some eighteen inches long. This gave enormous leverage, but ran the risk of breaking open the ring of the ring spanner, which had to be fairly aggressively thinned in order to fit over the nuts on the head studs. Eventually the point was reached where despite best efforts to immobilise it, the entire engine was beginning to move on the sump under the effort to tighten the head nuts. At this point I decided the head was tight enough.

Work on the rockers had been completed earlier, as their reconditioning was recognised as a long-lead item which could easily jeopardise the overall rebuild timescale. The original pins in the rocker arms, on which the rollers rotate, had been peened over to prevent movement and to retain the pins in the rocker arm. This requires a sort of heat-treatment conjuring trick, because the outer surface of the pin must be hard to resist wear from the needle rollers, but soft enough in the centre and at the end of the pin to allow it to be peened over after assembling the needle rollers into the inside of the wheel which follows the cam. The soft peened-over end of the pin allowed fairly straightforward, if careful dismantling, achieved by drilling exactly down the centre of the peened-over pin, removing material until it could be knocked out with a pin punch. Drilling was carried out with a hand-held Bosch battery powered drill. This tool allows very slow rotation of the bit and thus permits gentle and careful drilling. Although a bit slow, this technique was successful, and after about an hour's work twelve rockers without needle rollers or cam wheels, and with clean undamaged forks were ready for the machinist who would fit the new cam wheels and needle rollers.

The original design suffered from a couple of deficiencies, namely that the rollers, at about 1.5mm were too small in diameter, and there were probably not an optimum number. With the benefit of hindsight over 70 years later, and armed with some specialist information from Torrington, in respect of their needle roller bearing design procedure, a new design was put in hand. The smallest currently available size of needle rollers was 2mm diameter, so these were chosen, and a minimum order bag of 1000 purchased from Vintage Bearings. Then the Torrington design calculations were followed to select the appropriate number for satisfactory operation. This gives the right combination of clearances for satisfactory rolling, lubrication and stability of the race, and also determines the inner diameter of the cam follower wheel. Tolerances are very tight for all these components, as they need to be, given that the central pin is only about 8mm in diameter. The other major deficiency in the original design lies in provision for lubrication, and together these two design features probably produced very poor wearing qualities. The revised design used a central drilling and two radial ports to make use of centrifugal force to assist lubrication, whereas the original relied on external lubrication which would probably be defeated by these same forces. It is hoped that these changes will result in much longer life for the needle roller cam follower assembly. Geoff Harris did an excellent job of converting the revised design into reality, and a set of refurbished rockers was available when needed to fit to the rockershafts, once the head had been fitted to the cylinder block.

In preparation for setting the valve timing. a valve timing aid was made from a piece of polystrene which had been discovered in a tin of biscuits. It was suitably marked up with a protractor; TDC was marked on the disc, with 90deg lines marked in, and then more detailed degree markings over 45o on either side of TDC. Following this, it was fixed to the crankshaft damper with Bluetack. The camshafts fix to the head with 4 cast iron bearing housings, which also serve to maintain the required meshing of the camshaft drive gears. All the bearing housings and rockers slide off from the front of the engine after removing the retaining nuts, and reassembly is a reversal of this process. During dismantling, the final bearing bridge piece was left on the rockershafts, thus leaving the camshaft drive gears meshed together. Thus the relative timing of inlet and exhaust valve opening and closing events was undisturbed. The gears fit on to the camshafts by taper only, with no drive key. They looked very firmly attached, and since no particular benefit would have resulted from loosening the gears, they were left alone. Setting the valve timing thus required only establishing the position of inlet opening on number one cylinder, and checking the other events relative to inlet valve opening.

Fitting it into the 'Nash

The hole left after removing the non-standard Bosch distributor was filled by inserting a plug of aluminium from the inside. This job was carried out by a local machine shop which turned up a plug, screw cut to a BSP thread form. A matching BSP female thread was tapped in to the cam cover and the plug screwed in from the inside. Fortunately there is a reasonable amount of space inside the cam cover between the end of the exhaust camshaft and the end wall of the cam cover, which permitted the insertion of the plug with no problems. Finally, the cam cover was polished by a one-man-band in Tring, who did a 24hour turn-round for a reasonable price. The faintest of marks left by the insertion of the plug can just be detected after polishing, but overall this was felt to be a satisfactory result.

Fitting the exhaust manifolds and carburettors was left until after the engine was back in the chassis, in order to simplify the process of shoe-horning the engine in to the space available. The engine fits like a hand in a glove, with very little clearance at certain points, so a hydraulic crane was judged essential, particularly as the entire unit had to be lifted to a height of about three feet clear beneath the sump during the installation process to miss the headlamps. A local hire shop provided the tool for the job, which proved to be quite straight-forward. The only ticklish bit proved to be getting the two studs fixed to the flywheel which transfer the drive through the clutch to engage in the holes in the spring strips, in order to fit the nuts on. Once this was done the front engine mount could be fitted while the hoist took the strain, and then the whole weight of the engine was gently let down on to the chassis. The front springs settled a bit.

The carburettors had been completely stripped and cleaned, worn or damaged parts replaced, and the units built up on the bench ready for reassembly to the inlet manifold. The slightly gash original fuel feed pipe was used to check that the engine would run, but was subsequently replaced with a more appropriate feed, running the copper pipe from below. The engine was started up and run for a while and all sounded well. After a couple of short runs to secure a new MOT and for general checking purposes, a longer run to get everything fully up to temperature and to start the long running-in process began. However, a few miles away from home, with the engine warming up nicely, and with the water temperature at about 50 oC, the engine rattled for an instant and seized.
A Bad Moment.

After resting for a minute or two the engine was turned over with the starter and restarted, running quietly. About half a mile further along the road the same thing happened again, followed by a further rest and restart. Deciding that the run would have to be aborted, the car was driven very gently back home, with no further mishaps. But the damage was done, and it was clear that although apparently running nicely on all six cylinders, excessive blowby was occuring on some pistons, as evidenced by gales of fumes pouring out of the camshaft breather when the engine was revved. The problem was believed to be due to the combination of possibly inadequate piston/bore clearances and the use of a thermostat in the housing fitted at the top outlet of the cylinder head. It was apparent that the engine would all have to come apart again.

Confidence a bit shaken, I decided to let an expert have a look at this critical piston/bore interface. Steve White was prepared to have a go, and being very experienced in Riley engines, I felt he had what it took to do the job. The engine was removed, gently lowered into a small trailer and towed up to Leicestershire. Lifting the head and block revealed the two central pistons with aluminium scored and smeared over the compression rings, which were stuck fast in their grooves, hence the source of excessive blow-by. A set of new pistons and a quick lick for the bores later, Steve was able to reassemble the engine. Importantly he was able to use his years of experience to ensure adequate bore/piston clearances. The pistons, which were a bit obscure, were manufactured in Australia and sourced through Thorntons of Shrewsbury. Steve was able to take advantage of the Blackburne feature of head stud arrangement referred to previously, ie no need to disturb timing or valve clearances etc. The engine was run up on Steve's test stand, which permits a function check, but is a no-load rig, so power checks were not possible. However, all seemed to be well, so the unit was fetched in the trailer and refitted to the car. Once again it was started up, this time with no thermostat fitted. No thermostat has been used since, and it will probably stay that way.

After a few fairly short shake-down runs, confidence slowly returned. Arrangements were made with GDS in Brackley to make up a new downpipe assembly to bolt between the exhaust manifolds and the Brooklands can silencer. The car was driven over to Brackley fitted with the very old and rusty exhaust system which came with the engine, lashed up to allow the car to be driven the ten or twelve miles to the exhaust workshop. The new downpipe assembly was made in stainless steel, which is less suitable for getting the shape exactly right but which should last a long time. A few days after the engine was inserted into the car for the second time, it was due to appear at Brooklands for the 100th anniversary reunion event in mid June 2007. Engine matters and general running appeared satisfactory, when on the afternoon before I was due to leave for the event, the propshaft spigot bearing in the back of the flywheel disintegrated. The replacement bearing closest in size was larger than the original unit, and would require the flywheel retaining nut to be machined. With great reluctance, the attempt to get the car to Brooklands was abandoned. The dismantling, machining and reassembly job was done in two weeks, but the car missed the big event at Brooklands, to my considerable chagin.

Fifteen hundred miles or so later, the engine seems to have freed up nicely, with excellent throttle response. During the colder autumn and winter months a radiator muff has proved valuable to keep water temperature at between 70 and 80 oC when fully warmed up. Despite the lack of thermostat the engine warms up from cold quite quickly. The unit runs quietly mechanically, and despite having only a Brooklands silencer, the exhaust note is not particularly loud, although the sound is very satisfying. The engine has a good spread of torque, and the car keeps up well with modern traffic, with cruising at 70 mph or so entirely feasible. Overall, the project has definitely been worth all the hassle and cost. However I'm not really sure what it cost overall. When the total started to reach embarrassing levels I stopped counting.

The Engine back in place