Sprint Lucas distributor. An idea ?????

[MIG Wielder]

I was musing on the subject of this 44D4 Lucas dizzy that is fitted to the Sprint.
As I see it, the only reason B.L. fitted it was so that it would fit in the confined space under the manifold, with a low profile cap, funny rotor arm and spark guard. For instance none of the last 3 items are fitted to the MGB. I reckon the only other reason for these special parts is that they had to shorten the shaft to get everything to fit. And the funny rotor arm and spark guard are to stop the H.T. arcing over due to the shorter path lengths. Which is why the fitment of the usual "in-dizzy" E.I. units is a problem. And the reliability of these units may be a problem due to the heat from the engine.

A solution ?????

Looking at the front of the cam-cover, B.L. were obviously thinking " We need a PLAN B " in case this all goes pear-shaped. So they put the 1/2 moon cut-out in the front and bored out the front of the camshaft to take the main diameter of a Lucas dizzy shaft, probably a standard 45D4 MGB type.

So ... is it possible to fit a 45D4 inline with the front of the camshaft ? ( I think Ford did this in the '70s )
O.K. the cam would need the offset keyway machining out.
The cam cover would need a 1/2 moon cutout also machining.
But think of the advantages.
* A standard popular dizzy ( with the correct timing springs) etc.
* Running cooler as it is out in the open.
* Easier to set points and to fit a standard E.I.

Thanks,
Tony

[GrahamFountain]

I thought the 44d4 was used on one of the Lotus cars before the Sprint. In which case, it would have been a case of using what was available and would fit (mostly). I was told, a long time ago and without any conformation, the rotor arm shape and guard were for use in motorsport reason.

It might be interesting to see what the SD2 at Gaydon has, as that injected engine was meant for relatively large volume production. But it died with SD2/TM1 after BLMC went (nearly £3 billion) bust in 1974.

Graham

[tonybsa]

As a Toolmaker,I would think the half moon cut outs in the head, are so they could line bore the cam journals and caps in the head. Nothing to do with alternative distributor mountings.

[Carledo]

The problem with ANY conversion of this sort (I thought of using a dizzy cap on the front of the head/cam cover with a rotor on the cam gear like the Cavalier 8v has on the back, in conjunction with a crank sensor and Bosch motronic ECU) is that you still NEED the distributor (or some basic parts thereof) to drive the oil pump. And since you must have most of it, it makes sense to use it rather than duplicate it elsewhere.

In fact, if I ever DO build a Sprint powered car, it will run the Motronic with a crank sensor and EFi but use the distributor, completely empty, except for the rotor arm. Not much to cook there!

Steve

[Latham_F2]

I did think about using the half-moon at the front of the head as an alternative distributor mounting a few years ago.
It would have been relatively 'simple' on a Latham, there's lots of room.

But a Megajolt Lite Jr was a far better solution - a lot easier to engineer, guaranteed no oil leaks, and no more messing around with bob-weights or gaps. No coil (just a coilpack), no points or optical choppers to fail.

[cleverusername]

Unless you need a sophisticated system, just buy a ambassador cap, standard rotor arm and then fit a britpart or similar module. There is no need for any expensive or difficult engineering modifications.

As for heat, I don't see why that is even an issue with the current location of the dizzy.

[GrahamFountain]

Or, assuming you're desperate to get rid of points and condenser, then fit one of them modules with a Lucas 25D rotor arm under the standard cap.

Graham

[cleverusername]

Or, assuming you're desperate to get rid of points and condenser, then fit one of them modules with a Lucas 25D rotor arm under the standard cap.

Graham

Will it fit? I didn't think there was enough clearance.

[GrahamFountain]

Carl wrote:

Lucas Sport coil, Magnecor leads, Newtronic/Pirahna ignition, and a red 25D4 rotor arm. No ignition issues in 10yrs/~35,000 miles. Go for it !

I only ran one for a couple of miles as a test, after measurement said it was v. close for height and contact sweep diameter. Maybe a few thou smaller than the standard one. But with an electronic ignition module, I doubt a few thou matters.

Graham

[GrahamFountain]

Just wondering whether any of the other ones for the 25D and 45D will go under the 44D arm?

There's at least these:
https://www.ebay.co.uk/itm/Lumenition-E ... SwQ3Jdly6L
https://www.ebay.co.uk/itm/Sparkrite-SX ... SwLe5avKGF
https://www.ebay.co.uk/itm/Electronic-i ... Sw48tfT0KQ

I think they will all physically fit on the 44d baseplate at least.

Graham

[cleverusername]

Carl wrote:

Lucas Sport coil, Magnecor leads, Newtronic/Pirahna ignition, and a red 25D4 rotor arm. No ignition issues in 10yrs/~35,000 miles. Go for it !

I only ran one for a couple of miles as a test, after measurement said it was v. close for height and contact sweep diameter. Maybe a few thou smaller than the standard one. But with an electronic ignition module, I doubt a few thou matters.

Graham

I wasn't thinking of the rotor arm, I thought the britpart module was too tall to fit under the standard cap.

[GrahamFountain]

I wasn't thinking of the rotor arm, I thought the britpart module was too tall to fit under the standard cap.

I'm not absolutely certain of the make of the module I tested. It was a second hand one I found in a Dissy I got somewhere somewhen and it didn't actually work. But it looked like the ones from SimonBBC.

That one fit under the cap perfectly well; just not under the rotor arm. You can also shorten the brass on the 45D arm and use that with the 44D cap. But I'm not sure I know anybody [else] mad enough to do that just to see if it fits.

Graham

[GrahamFountain]

Pictures of it are here?https://forum.triumphdolomite.co.uk/vie ... =4&t=35845

[GrahamFountain]

Motortronic on ebay reckon to have a unit that does go under the 44D rotor arm. Unfortunately they don't recommend it with the ballasted 6v coil. They say that "some customers have run them with the 6 volt system and say it runs ok but the coil gets very warm". Since I want to go back to standard just for swapping out the dizzy, I don't think I want to swap the coil or its wiring (and I just bought a new one anyway). Assuming the heating is due to a greater rate of change of current as a component of L.di/dt, it's possible a capacitor on flying leads across the coil might reduce it enough to stop it burning. But it's more messing than I'd want to do.

The link to the unit is this: https://www.ebay.co.uk/itm/142935740137, but the picture is wrong. The correct unit is shown here:https://www.ebay.co.uk/itm/Triumph-Dolo ... Sw3WZfT0Kz.

Graham