The Triumph Dolomite Club - Discussion Forum

Need to sort my distributor out as the timing jitters too much at low revs and a previous owner has butchered the baseplate. Try to work out what distributor the car should have. There are three listed in R.O.M.

41402 (313177), 41589 (RKC 0695), 41655 (RKC 3034)

The difference appears to be the vacuum and centrifugal advance curves. I have looked in the 1975 parts book and the change between 313177 and RKC 0695 occurred at engine number VA6183E

My car is a 1975 model Chassis No. VA15xxxDLO Original engine Number was VA011xxxHE

BUT the engine in it now has the number VA23xxESS which I think was a factory service exchange engine. This appears earlier than the original. The current distributor is a 41402 which seems to go with the engine number.

So question is what spec should this engine have and does it really make any difference?

Roger

It looks like you have the correct distributor for an early engine.

Page 05-1 of the AKM 3629 Sprint workshop manual gives the basic advance differences between the 3 distributors.
But note the misprint in the Centrifugal crank; advance data. "Maximum type C " in the first column should be "A".
To summarise the data, the average centrifugal crank; advance at 2000 rpm is 14 deg (early) , 17 deg (2nd type) , and 11 deg (3rd type ).
There are a lot fewer data points for the Vacuum advance curves for the two later dizzy types.
At 18 ins Hg Type 1 is average 10 deg advance, type 2 is 10 deg at 13 ins Hg , and type 3 is 14 deg at 8 ins Hg with No advance below 2ins Hg.
HTH,
Tony.

my thoughts...
I don't think the cam or head changed during production? (If they did the that would explain teh dizzy changes)
If no mechanical changes, why did the dizzy spec alter?

Anyway, a well functioning dizzy is very desirable. Worth getting rebuilt or suchlike. In fact I wouldn't be surprised if a competent dizzy builder used a different curve as todays fuel is so different from the old 5 star.

If pocket depth allows the distributor doctor is worth a call, or H+H ignitions.

The ESS engines had their own numbering series, there's no way of telling what year the engine you have is. But my guess is it will date from around 78-80.

But the only REAL difference between the first and last engines is the casting of the cylinder head, the later one being an allegedly better design. However no fundamental internal changes took place. Valves, cam, compression ratio, combustion chamber volume and so on remained unchanged throughout the lifespan of the engine. My guess is that the first dizzy changed to adapt to the loss of 5 star fuel which happened around the time the Sprint was launched and the second change as a refinement.

I doubt there is such a thing as the "right" dizzy for any particular engine, once the years and miles have had their way, it's all pretty much guesswork. And it's a sure thing that a BL dealer would supply the latest dizzy available if asked for a new one, regardless of engine number! Or possibly even offload an earlier one he had lying around!

But if bodging is evident and the low rev advance is dancing about, i'd recommend a rebuild by a reputable specialist like Distributor Doctor. Someone like Jeroen (SOE8M) of this parish can probably advise on the sort of curve you need for this engine, which will also depend on the state of tune.

Steve

Thanks for the info/thoughts, pretty much fit what I was thinking.

Steve, interesting, I didn't realise the "SS" engines had their own number sequence. I thought they might be factory recon/rebuilds of dealer returned engines and they just stamped SS on the end to identify them. If what you say is true then all bets are off as to the actual age/type. My engine does not have the later head casting.

I have been in touch with the Distributor Doctor and will probably go that route with the "early" distributor as the advance curve seems to sit in between the other two.

I had a read of the threads on the 123 distributor and also thought about megajolt etc, but I like to keep my cars fairly standard/factory and didn't want to spend too much time on it as I have other projects waiting. The thread on adapting a 123 to fit the sprint was an interesting read though.

For those that are interested a 44D4 rebuilt by the Distributor Doctor is £366 inc P&P and VAT (no cap fitted as he hasn't got any at the moment & will only supply original Lucas ones). That includes a £100 surcharge refundable on receipt of your old distributor. He can do any of the 3 specs - or anything else you ask for.

Roger

How much?

OK I know that I am tight but for that kind of money I would have a bash at it myself, they aren't that difficult to pull apart.

Can't argue with you. Thought the same myself, I usually do repair/rebuild/restore bits myself. Bear in mind £120 of that is surcharge, so actual cost is £246, still a lot I know. In this case I have already had it apart. It is really worn. the main shaft wobbles, a lot. The drive gear is worn (jackshaft looks ok, suspect it as been replaced at some point). The base plate is bent and butchered, advance weights catch the outer casing and are quite battered. Vacuum advance unit is also very sticky, not convinced it is working correctly if at all as I did try to check it with a vacuum pump and guage. Virtually every part bar the main case needs replacing. Totting up the cost of all the bits, assuming I can get them all , in this case it is worth it to me and it leaves me to get on with other stuff and be enjoying driving the Sprint, it is what I got it for

I think you have just answered your own question. The play in the shaft will cause the timing scattering you're getting and you can either gut it refurbed or fit electronic ignition which isn't generally affected by play in the shaft. A cheaper option would be to source a good used dizzy.

I MAY have a spare base plate if that assists DIY...

Toledo Man wrote: ↑Tue Jan 14, 2020 7:08 am I think you have just answered your own question. The play in the shaft will cause the timing scattering you're getting and you can either gut it refurbed or fit electronic ignition which isn't generally affected by play in the shaft. A cheaper option would be to source a good used dizzy.

Been looking for a "good" used on for a little while, not seen any. Also not sure there will be many such animals about as the 44D4 is unique to the Sprint. It already has electronic ignition fitted. To be honest when I pulled it apart I was surprised the car ran at all as the vacuum advance unit was not connected to the base plate leaving it free to turn if it wasn't so butchered that it was jammed up. I did straighten it out and free it up but it hasn't made much difference.

xvivalve wrote: ↑Tue Jan 14, 2020 8:15 am I MAY have a spare base plate if that assists DIY...

Thanks for the offer, much appreciated, but I have decided to break the habit of a lifetime and "splash some cash" [ooh that hurts to say that] and get a recon one from the Distributor Doctor - extravagant but the car is a keeper so worth the investment in the long run. There are cheaper "recons" out there but in my experience things are usually cheaper for a reason and I would rather buy direct from person doing the work rather than through a third party.

My initial question was really to see if it mattered which of the 3 types I fitted and why they differed. I think Steve's "guess" on the history may be correct so I'll go with the early one (in the middle of the advance curves) and go from there. Interesting that they didn't mess with the carbs at all, there is only one needle listed as far as I can see.

Thanks for the input

Roger

Wow that old one really is a catalogue of disasters! I think you are making the right choice here!

I think the only one i've seen worse was last year or the year before, in that case the vac advance had been removed completely, also the upper part of the baseplate, then a Magnetronic had been bodged onto the lower section of the base plate with self tapping screws. Besides that the bearings were shot and the bobweights were seized onto their stubs! The engine it was attached to was a cracker, with a ported and flowed head, balanced bottom end, TT10106 cam and dual 48 webers, yet it ran like a bag of nails with that on it! Actually, it's a minor miracle it ran at all! Even a stock second hand points dizzy from Alun made a world of difference!

You sometimes have to wonder who DOES this sort of work! And how they justify it?

Steve

Carledo wrote: ↑Tue Jan 14, 2020 11:35 am Wow that old one really is a catalogue of disasters! I think you are making the right choice here!

I think the only one i've seen worse was last year or the year before, in that case the vac advance had been removed completely, also the upper part of the baseplate, then a Magnetronic had been bodged onto the lower section of the base plate with self tapping screws. Besides that the bearings were shot and the bobweights were seized onto their stubs! The engine it was attached to was a cracker, with a ported and flowed head, balanced bottom end, TT10106 cam and dual 48 webers, yet it ran like a bag of nails with that on it! Actually, it's a minor miracle it ran at all! Even a stock second hand points dizzy from Alun made a world of difference!

You sometimes have to wonder who DOES this sort of work! And how they justify it?

Steve

Sounds exactly like mine (except weights were the opposite of seized - i.e. loose and floppy!) - self tapper and all!! Are you sure you didn't sell it on and fit to my car

marshman wrote: ↑Tue Jan 14, 2020 12:08 pm

Carledo wrote: ↑Tue Jan 14, 2020 11:35 am Wow that old one really is a catalogue of disasters! I think you are making the right choice here!

I think the only one i've seen worse was last year or the year before, in that case the vac advance had been removed completely, also the upper part of the baseplate, then a Magnetronic had been bodged onto the lower section of the base plate with self tapping screws. Besides that the bearings were shot and the bobweights were seized onto their stubs! The engine it was attached to was a cracker, with a ported and flowed head, balanced bottom end, TT10106 cam and dual 48 webers, yet it ran like a bag of nails with that on it! Actually, it's a minor miracle it ran at all! Even a stock second hand points dizzy from Alun made a world of difference!

You sometimes have to wonder who DOES this sort of work! And how they justify it?

Steve

Sounds exactly like mine (except weights were the opposite of seized - i.e. loose and floppy!) - self tapper and all!! Are you sure you didn't sell it on and fit to my car

That was YOUR car?

I had thought of keeping it as a "black museum" piece, but sanity prevailed and I binned it!

Steve

I had thought of keeping it as a "black museum" piece, but sanity prevailed and I binned it!

Shame, I'd have bought it for the case as I have a couple with broken mount slots.