Fitting a Lucas 45D4 Distributor to a TC

2 Jun

In the December 2018 issue, John Saunders described how he fitted a Lucas 25D4 distributor with vacuum advance to his TC. Steve Priston found John’s article invaluable when he fitted a 45D4 distributor to his TC.

I now consider that I have successfully fitted the Lucas 45D4 distributor to my ‘48 TC, having overcome some recently experienced teething problems, which was nothing to do with the original concept, just something very useful to note, for others intending to do the same modification.

This was the fact that I had purchased a distributor for a Mini, which I believe engages into an extension shaft, spacing it well up, out of the way of the hopefully plentiful, gushing oil supply around the camshaft.

If you look carefully at the body & lower spindle of a similar 45D4, you will clearly see the measures required, when this unit is exposed to a plentiful oil supply, firstly a hole, drilled just above the top edge of the lower bush, with its corresponding groove down, the second very important thing to note, is the oil scroll, starting where the lower spindle is waisted, dropping down to the area just above the drive gear, where in my case I have fitted a sintered bronze thrust washer, now having four trailing oil flinger grooves on its top face.

This change from the standard plain spindle & total lack of an oil hole, as employed on the Mini set-up, has prevented the considerable amount of oil from winding up the lower spindle, then draining out through the four or so holes, cast into the distributor body, below the centrifugal advance mechanism, making quite a mess!

The photo shows what is employed on a Land Rover, to be fair, I am not sure whether the hole is to allow oil to be pushed into the cavity between the two bushes or to let it drain but on mine because of the position for the spigotted retaining bolt, which locates in the groove, that needs to be copied from the original unit. I decided to drill two holes, either side of what would be the ideal spot, being the lowest point because it would be straight under said bolt.

The Mini distributor got the “Dremel treatment”, a permanent marker line, replicating the Land Rover oil scroll, was then ground, using one of the little black cutting discs, with the business end of the spindle wrapped carefully in cling film for the duration of the groove cutting.

It was then polished with 1000 grade wet & dry, removing any sharpness so as to not carve away the bottom bush!

Having been extensively tested today, by cruising at 50 to 55mph, it has done the job, preventing me from having to disturb the work of Martin Jay (The Distributor Doctor), who had set-up the advance curve, as specified by John Saunders because by doing this mod to the lower spindle, I did not have to dismantle any more, than just removing the spindle assembly as a whole.

I provided Martin with what was described on eBay, as a reconditioned Mini 45D4, which had the advantage of having a 10 degree centrifugal advance, allowing me to file back the stop, whilst checking the movement with a timing disc, to give me the desired 13 degrees so that the unit would advance the timing 26 degrees, allowing for a 5 to 6 degree static advance, thereby not over advancing the engine (all in John Saunders’ article).

It is definitely a good idea to remove the original unit from your engine so that all the required alterations can be made to the later one or to list them, if the work is to be entrusted to someone else.

Like the distance to machine back the shoulder, to allow correct alignment of the drive gear so that the witness mark on the gear teeth will end up on the centre line of the tooth etc.

I only used Martin to set-up the advance curve to John Saunders specification but when asked he says he is able to do all of the required work, something to consider, also to get a quote because if unlike me, you are not one to enjoy fixing things with a “fag paper”, it might be cheaper/as expensive to go with an electronic unit, that can be programmed, if you are having to “farm it out”?

I have to confess that this whole project is straightforward, when it comes to acquiring the required parts, by simply searching eBay, where NOS bits are still to be found, like genuine Lucas 5-13-10 vacuum advance units, I also bought the pipework, as seen in my photos, its all there, like genuine Lucas points for £2.80 all in!

If you want to use a drilled core plug, as I have, to avoid drilling the manifold, they are 28mm diameter & about £2, another thing to note is that the vacuum pipe kit that I have used contains sufficient brackets, also with its small chamber fitted, I think starting is improved, as the vacuum effect is delayed because it needs to accumulate first, via a very small bore pipe.

I have used a small length of nylon piping, with both a straight rubber & elbow connector, for the joint with the vacuum unit, allowing freedom to rotate.

The 45D4 is quite close to the components around it but doesn’t touch anything, if set as I have, you might have to acquire a different length of fan belt, I am using a wider than standard Dunlop BX38, which allows clearance for the original tacho-drive, not a change, it just fitted with it on there but you will have to remember to remove the reduction box before moving the dynamo position.

As can be seen, it will fit with the standard side cover on the engine or the fancy alloy one, that in my case dribbles oil, which is why I swapped it back.

There will be some frigging to do, to get it all to fit together but nothing at all daunting, access to a lathe is pretty much essential but it isn’t difficult to machine what’s required, the old core plug just requires a small hole drilling in it, to prise it out carefully, being mindful of where the swarf could end up, bracket holes need enlarging with a file, basic stuff.

The result is a lovely smooth engine at about 50mph, that should as John Saunders has explained, run cooler at part throttle openings, where so many of these engines spend their lives, on our either congested or potholed roads, delivering slightly higher mpg.

Thanks Mr. Saunders, you inspired me!

Steve Priston

Ed’s note: On reviewing his article, Steve asked for the following important information to be added:

“It is very likely that if as I have, you wish to retain the micrometer adjustment mechanism, you could find that there is considerable wear present in two places, which allows the timing position to wander, the first one that I found, was the pivot attached to the alloy casting or main body of the adjuster.

For this I entrusted a very clever retired Toolmaker friend, who machined the pin round again, over bored the pivot hole, fitting a nylon bush.

The second issue being the backlash/excessive wear in the left handed thread of the adjuster, both of these areas of wear, allowed my distributor body to rotate an alarming amount, despite the clamp being tight.

I overcame the slack adjuster thread by stretching an “O” ring or two over the adjuster’s thumbscrew, filling the gap between the alloy body & the back of the knurled knob.

When I spoke with John Saunders, he had addressed this by use I believe of a tension spring, either way works & John’s may well sort both problems?”

Ed’s further note: I leave you with a picture…..


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