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Lucas distributors as fitted to Rolls Royce "B" series motors.
   (Ver 2)

 

From Richard in England comes the following article regarding rebuilding the Solex carburetor. It is taken from several replies he has made on Mil-Veh-List over a number of years.

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The B Range dissy needs a regular oil, like all dissies, down the centre of the cam to keep the sleeve free and the A/R (Advance/Retard) mechanism free. You should also oil the shaft bearings under the big slotted screw on the casting, to say nothing of a regular lube of the contact cam heels, the plastic or fiber material will wear almost instantly if dry and have the cam lobes away also.

I can obtain copious quantities of original B Range points, condensers, rotors and caps, they were all laid out at Beltring anyway on Marcus Glenn's stand, boxes and boxes of them.

10514

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Partial "B" series specs.


B 60
The Ferret with its 6 hole lump fires apart 180 at the dissy and so 360 apart at the flywheel, therefore you time the FIXED points on the flywheel marks (at 0 - 2 AFTER TDC), rotate the motor 360 and move the moveable point set within the dissy to obtain firing also within the 0 - 2 after spec.

You do not need to remove the dissy on the Ferret or any B Range six as there are two pots that fire 360 apart, unlike the eights where you are obliged to fabricate the setting tool with a clamp-on 45 quadrant that allows you to set the "other" points precisely with the dissy removed relative to the fixed ones that are timed from the engine itself after replacement.

With the B 60, after gapping and replacement as required, you simply set the fixed points against No. 1 firing on the timing marks (0 - 2 _ATDC_) using the classic bulb and battery method, then rotate the engine 360 forward to the marks again and do the internally moveable set.

B 80 and B 81

The Saracen B80 (3.5" bore) and B81's are 8 pot motors and fire 90 at the crank so 45 at the dissy, the latter can only be set removed from the vehicle with the appropriate jig whereby replacing it and doing standard static timing has the 45 points correctly in unison with the fixed set.

RR B Range dissys are wholly misunderstood world-wide, not only do they use half the cam lobes that there are cylinders but fire cylinders alternately from the twin points and provide dwell angle extention thereby, the eight cyl dissy can also be used, and is so marked, on the four cyl B40. Do not forget across the entire range of RR B Range engines some 207 individual parts are used and of these 184 are common and interchangeable.

Regarding a B 80 in a Saracen:

>Anyone want to volunteer to try to start this puppy with a hand
>crank?? :-)

Its actually very easy with the proviso that the RR B 80 is in reasonable order, the ignition is correctly set and you follow the procedure laid down; we have hand cranked the bigger B 81 in my FV 623 with ease.

From cold the procedure is to hand operate the fuel pump to ensure a carb prime, hand crank several revolutions with the choke fully on and ignition off to prime the engine, then swing it, while a second operator simultaneously hits the start button. The procedure assumes that the hand crank is used because the batteries are flat and will not turn the motor, operating the starter does two things, firstly it by-passes the ignition ballast resistors putting what volts there are directly on the coil and secondly after getting the engine over one compression the starter helps hugely even with very low volts and likely does most of the work once you have got some small initial momentum in the engine.

It is absolutely crucial that the ignition is correctly set, do not ever attempt a hand start on any B range engine unless you personally know for sure this is the case.

All B range RR engines, 4's, 6's and 8's, Champs to 432's, are set 0 to 2 AFTER, I repeat AFTER, TDC and can only be set statically. The centrifugal advance operates from 300RPM upwards so a strobe timing light can NEVER be used, nominal idle is 450 to 600RPM. The timing after TDC means the engine cannot kick at start.

The B Range distributor, Lucas No1 Mk 2, is designed to be common with the whole range of engines by using two cam types and two internal cap types, you will notice the cap has alternative circled cylinder numbers moulded in it for 4 and 8 cyl engines. On 4 cyl engines half of the connections are used with _one_ set of points only.

You will note there are only FOUR lobes on the cam and two sets of points on the eight cyl engines.

This arrangement is totally and utterly different from the old US practice of an EIGHT lobe cam with two sets of points arranged to give dwell angle extention and hence a stronger spark.

These 8 cyl B Range engines have one point set firing four cylinders and the other set firing the ALTERNATE four, 45 distributor degrees, so 90 crank degrees, apart. Whilst the engine timing is conventionally set with a lamp, engine static on the flywheel marks and the distributor swung as normal, this wholly assumes the second, moveable, points are critically preset 45 to the fixed ones. If not half of the engine will be mis-timed.

There is a very complicated and unwieldy procedure for doing this by measuring inlet valve clearances with a specific pair set to timing clearances, however it is much simpler using the simple maintenance manual tool consisting of a self-made 45 quadrant on a boss that clamps where the rotor arm goes and a sheet brass U shaped "table" that clamps through the vent and LT cable holes that you can stick masking tape to and mark from the rotor arm quadrant.

10515

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Richard's home made alignment tool in use.




10553

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The distributor jig specs. Note that this is a large pic scanned in at 200 dpi so you will probably need to load it into a graphics programme to print it.
Bolt thread types are immaterial, whatever is to hand will do of similar size that you have the nuts or the tap for. It is obviously critical that the 45 quadrant soldered onto the bush is dead accurate, it is better to make it slightly oversize, align it with a mandrel and accurately draw file it after assembly.


This is done with the engine preset to the nominal, centre spec, 1 AFTER TDC No 1 firing (as the distributor will fit 180 out), noting where the rotor arm is (about 7 o'clock looking from the distributor side) and removing the whole assembly to the vice and the bench.

Having serviced the points or replaced them, gap correctly, lubricate and proceed to utilise the jig to adjust the moveable set exactly 45 from the fixed pair opening point with a battery/bulb timing light, then refit to the vehicle and reset the whole distributor against the marks, as previously aligned, with the battery/bulb set-up as usual.

Richard
(Southampton UK)

My thanks yet again to Richard.

 

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