Distributor replacement

[BrianJT]

The DM2P4 Lucas distributor fitted to my 1959 Herald 948cc, twin SU H1 carbs, engine has a few wear problems. Has anyone got any views on whether to go for a refurbished unit (ex Rimmer Bros for example) or to fit an electronic conversion. Some seem not to 'worry' about wear on centrifugal weights, etc. but it seems to me that merely replacing the points with an electronic version may not overcome the problems of misfiring, erratic timing and so on.
All comments gratefully received.

[Mark Hammond]

Try the Distributor Doctor.

Mark

[npanne]

I used H&H for a dizzy refurb - very impressed with the results.
http://www.h-h-ignitionsolutions.co.uk

No connection / vested interest etc etc

[BrianJT]

Thank you Mark and npanne for the replies. I'm interested in the statement by H&H about a 2-day turnaround but I suppose that this carries a cost premium - any possibility of a PM re costs, etc?

[Bitumen Boy]

I wouldn't get a recon diz from Rimmers, I've seen one before and wasn't impressed. Got it sorted in the end but not nearly such an easy job as it should have been.

[Jonny-Jimbo]

I got my Lucas dizzy for my Mk1 refurbed by H+H, and I was very impressed it really was like a new unit when it came back. I had to get it done as there was play in the shaft and the little thread that held the points in was stripped too. The car runs so much better than it did before (anyone at the start of HCR would have seen how badly it was running!). From memory it was around £135 fully refurbished, which is quite a lot, but it was worth every penny.

[BrianJT]

Hi all and thank you for the two H&H prices sent - they seem to be what I was expecting.
I've ordered an electronic ignition module as a stripdown of the DM2P4 did not reveal as much wear as the performance had been suggesting and I'll see what results from fitting it.

[piman]

Hello Brian,

it's always worth checking if your distributor is the correct one for your engine, there should be a five or six digit number stamped on the body, which can be checked against a workshop manual or possibly someone here knows what it should be. Also it is possible taht the incorrect parts ahve been fitted in the past which would affect the curve, this also applies to the vacuum unit, if it has one

Alec

[Casper]

Lucas No.       Car                              Type     Stanpart No.
40637     Herald  948 cc 8 :1 CR          Lucas DM2     205342
40638     Herald  948 cc 7.4:1 CR          Lucas DM2     205330
40638     Herald  948 cc 8.5:1 CR          Lucas DM2     205330
40658     Herald  948 cc 7 :1 CR          Lucas DM2     206070

I haven't got the advance capsule number (or spec.)

C.

[BrianJT]

Many thanks for the last two replies both of which have opened up a new can of worms for me. Re. the vacuum advance, I was told by someone in the know that although my capsule was punctured, it didn't matter because it was only active at low revs. This claim was verified by another advisor who said that when he used to race cars, the capsule was deliberately made inactive. Do these two claims make sense or should I therefore fit a non-punctured capsule?
I don't know what the number on the DM2 is but it's the same that was on the original 948cc unit that was transferred to the re-bored 1147cc unit that replaced the 948cc unit in 1973. It was then used until 1978 without problems before being laid up (abandoned in the garden is a better description) and eventually restoration started in 2009! The original 948cc unit was delivered in August 1959.

[nang]

One thing with the punctured diaphragm is that you're going to suck unwanted air into the system.
Tony

[Nick Jones]

Any air leak from the punctured diaphragm pales into insignificance again the loss of torque at part throttle.  I suppose you could argue than on a Herald 948 you are mostly at full throttle anyway....... but the vacuum advance on a road car has the effect of increasing ignition advance at part throttle giving a significant increase in torque and helping fuel economy.  I'd say you want the vacuum advance working!

Nick

[Jonny-Jimbo]

Going back to what I said about getting my Lucas rebuilt (Although the topic has moved on, I feel this may be of interest to people reading this post anyway or have similar issues), my car had trouble starting for ages, and in fact it was off the road for over a year due to on-going running issues.

In the end the issue was two fold - electronic ignition unit failure, and the worn dizzy shaft. I junked off the Lumenition unit and stuck a set of points and a condensor in and the car fired up nicely straight away after a year of problems with it cutting out etc. However, it still ran badly, which was down to the dizzy shaft wear and the little thread being damaged meaning the points weren't clamped adequately.

Now the dizzy has been rebuilt I can just get in, turn the key and she fires right up.

[Casper]

If you take a wire brush to the Vac capsule you will find the Lucas part number (8 digit), and the vacuum spec.
(let me know with the dizzie number and I can update my records!)

If you currently have a 1200 engine then the correct dizzies are

Lucas No.     Car                                    Type             Stanpart No.     Vacuum     Vac Adv Unit No.     Mech Adv at Dizzie

40743     High C up to 1964                     Lucas DM2          208362        3-7 8       54415212               5
40791          High C 1964 on (Hit Cam)       Lucas 25D4          208968        3-7 8       54415212               10
A very satisfactory replacement for ant 1200/13/60 Herald is :
41449          Spit 1500                           Lucas 45D4     RKC5044    5-12 6       54424752               8

C.

[BrianJT]

It's obvious that some more investigative work is required but I'm crossing everything that replacing the points/capacitor with an electronic version tomorrow will sort out my immediate problem.
Although the vacuum capsule is punctured, I have sealed off the end of the tube that is connected to the rear carb. so there shouldn't be any air getting in that way.
Update to be posted later.

[piman]

Hello Brian,

I agree with Nick and having the vacuum working will be benefitial. You mention a racer but that is a completely different situation than a road car
To amplify, a car with a vacuum advance has it's carburation weakened at the cruise area to improve economy, and without the extra advance given by the vacuum module the car would be running too retarded. Manufacturers spend a lot of dynamometer hours to set up both the ignition and fuelling (together), which is why the distributor specification is important.

If people like the Distributor Doctor don't have the correct units, I found this (Ameriacn unfortunately) site:-https://www.britishvacuumunit.com/

Alec

[BrianJT]

Hi to all, A long overdue update following illness and hospitalisation of my other half - still ongoing but progressing.
Previous posts re my car revealed that the car is a 1959 Fairthorpe kit car that uses Herald and Standard 10 parts.
Following my last post, I replaced the points/capacitor with an electronic module and changed the plugs back to 3/4 inch reach from the previous 1/2 inch ones that I had been using. The result of these changes, without altering timing or mixture settings, was an increase in idle speed to about 2000 rpm.
I chose not to make any other changes before an upcoming club gathering and then clocked up about 200 miles on the round trip without problem.
The fast idle has still to be sorted out - suggestions welcomed - but I've now realised that an upper limit of 60 mph on the M11 is probably due to the unmatched exhaust system. However, the plugs were not at all sooty so 3/4 inch are better.
The original supplied exhaust system, probably Standard 10, has long since disappeared and I chose to use a side exiting silencer just before the O/S rear wheel with a short front pipe. It's very noisy and, I believe, needs to be replaced by items that are more suitable to the 1147 rebored to 1174cc engine that I am now using.
So my most immediate need now is to obtain details of the exhaust system item sizes as fitted to the Herald 1200 cars. If anybody has the original Stanpart, or whatever, part numbers for the muffler, tailpipe and the front pipe (between the muffler and exhaust manifold), that would also be very useful.
I have come across a formula that gives guidance on the total muffler and front pipe volume which should be between 2.5 and 3 litres - my present, noisy muffler has a volume of 4 litres so this really could be the cause of noise and low power - all comments appreciated. The calculated volume of the muffler for the 1200 cc engine is just over 2 litres thus leaving 0.5 to 1 litre for the front pipe.
As usual, all comments will be gratefully received and I'll post a photo of the car when present pressures are reduced. Thanks to all in advance.

[BrianJT]

Thank you Alec, that's very useful information. It shows how getting just a snippet of - usually incomplete information, as in the vacuum not used on racer - can create more problems than it resolves.
Brian

[Casper]

Sorry, after posting I reread the thread and see you have 1 1/8" SUs on a 948 manifold.
The 1200 carbs are either 30mm single or 2 x 1 1/4" SUs.  I would be inclined to get this sorted before thinking about the exhaust.
Search the site for conversions to twin SUs for 1200 engine.   And then there are camshaft options to consider.  What is the engine number?

C.

Start with the manifold.
You have the option of
948: http://www.canleyclassics.com/triumph-herald-948-oil-pump-and-manifold
1200:  http://www.canleyclassics.com/triumph-herald-1200-oil-pump-and-manifold
12/50:  No link, but likie the leftmost 948 - longer exhaust tracts than 1200, and larger bore
Spitfire Mk II:  http://www.canleyclassics.com/triumph-spitfire-mki/ii-mkii-manifold-details
Spitfire 4 (Mk i) No link, but exhaust similar to 948 and 12/50

What have you got fitted?

C.
  

[BrianJT]

Hi Casper,
Thank you for the info. At present, I can't justify the cost of replacing carbs and/or manifold as I have just spent several hundreds on having the H1 carbs re-built.
I ran the car at something like 350 miles a week for five years after fitting the re-bored 1147cc engine and had no problems.
At the time, the exhaust consisted of a short front/down pipe with an over the counter 4 litre volume muffler emerging from the side under the driving seat.
The exhaust was not noisy and I had sufficient power to meet my commuting requirements.
I only replaced it when I started a wheels-up rebuild in 2009 and had a stainless steel muffler built to the same external dimensions so that it would fit in the same space.
Nothing else was changed and that is why I'm seeking info on what members with 1200cc engines are using.
Incidentally, the exhaust manifold matches item 6b on the diagram from the 948cc link.
Regards, Brian

[Casper]

Quoted Text

the exhaust manifold matches item 6b on the diagram from the 948cc link.

In that case I suggest a 12/50 front pipe will probably mate with it, but you might need to check a parts manual to see whether the gaskets are the same.  I think the 12/50 may have a larger bore, but the PCD might be the same (or not as the case may be).

[BrianJT]

Thanks for that, Casper.