Do I need a new distributor

[cliff.b]

When I got my Spit 1500 running in the Summer I had some distributor related issue including a seized vac unit and very little centrifugal advance.

I replaced the vac and cleaned/oiled everything else which made a big improvement but needed to set static timing at 15BTDC to get best performance.

Now the car is in the garage I'm taking another look at it and using my strobe, I'm only seeing a max additional advance of about 8 Deg when increasing revs.

I thought it should be more than that and would be interested in any opinions. Is this a valid test? Is this why I have needed more static advance? Am I right in thinking this could be down to a worn dizzy?

[Clive]

Have a delve inside the dizzy and look at teh springs. They may be very stretched, or teh pins worn (had that on my dolomite)

If it is the dizzy, I would not be buying a brand new chinese made one. You should be able to get replacement springs, and that may fix it. Otherwise Distributor doctor or H+H for a rebuild.

[NonMember]

It does sound like you've got a faulty mechanical advance. I've had success in the past with dismantling, cleaning up and reassembling with plenty of lubrication. But only on early Lucas 25D ones. The later Lucas on a 1500 might be OK. Mine's a Mk3, though, with the Delco, where any attempt at dismantling results in destruction. I had to buy one of the "brand new chinese made" ones, which appears to work fine.

[Pete Lewis]

trouble is very few Oil the dizzy , some have a hole in the base plate with "oil" stamped in  delco are the worst for top bush and spindle wear lucas not far behind

the top bush is not engine lubricated and does need a squirt or two now and again as a service item 

after 50 years of running dry they give up some dizzy have a felt oiler in the base to help 

dizzy doc can sell you springs ,if its a lucas a 45 is less diy strippable than a 25D 

and agree with Rob a delco is mend it to destruction

Pete

[cliff.b]

21 hours ago, clive said:

Have a delve inside the dizzy and look at teh springs. They may be very stretched, or teh pins worn (had that on my dolomite)

If it is the dizzy, I would not be buying a brand new chinese made one. You should be able to get replacement springs, and that may fix it. Otherwise Distributor doctor or H+H for a rebuild.

Are the ones branded as Lucas any better or just in a different box?

[Clive]

1 hour ago, cliff.b said:

Are the ones branded as Lucas any better or just in a different box?

Lucas just make boxes.  They put tenders out for suppliers to make "best value" parts. ie biggest profit margins.

So I avoid lucas wherever possible. YMMV.

[cliff.b]

2 hours ago, clive said:

Lucas just make boxes.  They put tenders out for suppliers to make "best value" parts. ie biggest profit margins.

So I avoid lucas wherever possible. YMMV.

Hmm, thought that might be the case.

Do all 45Ds have the same advance curve or do they vary?

Looking at the inside of mine it has an 8 stamped on the stops so I presume it should (but doesn't) give 8deg advance at the dizzy and therefore 16deg at the crank. 

Does anyone know if this is what is supposed to be fitted?

[Clive]

Distributers will be curved to their application. ie mini different to spitfire.

You are correct, the baseplate shoud give8 degrees of dizzy advance from statis, but much of that may be lost by wear and stretced springs.

[cliff.b]

43 minutes ago, clive said:

Distributers will be curved to their application. ie mini different to spitfire.

You are correct, the baseplate shoud give8 degrees of dizzy advance from statis, but much of that may be lost by wear and stretced springs.

Ok, I suspect that is what is happening. Difficult to know how it is affecting things as I have never known the car without this. Be interesting to see if there is a noticeable difference once I have sorted it out.

[cliff.b]

Been looking at my dizzy again and see it's a 41449 which I believe is the correct one.

Does anyone know what advance  springs are supposed to be fitted as standard?

[Colin Lindsay]

I can't find the actual dimensions but I've found springs:

https://simonbbc.com/spring-set-for-lucas-45d-distributor/

The Distributor Doctor site says that if you give them a call they'll supply the spec of any distributor from a stock of over 150000 springs....

http://www.distributordoctor.com/distributor_advance_springs.html

[cliff.b]

5 minutes ago, Colin Lindsay said:

I can't find the actual dimensions but I've found springs:

https://simonbbc.com/spring-set-for-lucas-45d-distributor/

The Distributor Doctor site says that if you give them a call they'll supply the spec of any distributor from a stock of over 150000 springs....

http://www.distributordoctor.com/distributor_advance_springs.html

Ok, many thanks 👍

[cliff.b]

I have now found listings of the advance curves for a large number of different Lucas distributors but nothing about the springs fitted to achieve those curves.

During the course of looking though, I have read that owing to relatively loose tolerances in production, suitable springs were selected to give the required performance for each type during post manufacturing testing.

I suppose this would explain why I can't find any information on springs, if it varied.

This came from an MG site which also gave useful information on how to choose springs. It also looks like MGBs have a far more aggressive advance as standard than Triumphs and I'm wondering why that would be?

[Wagger]

In 2002, two of us were having bother timing a 1098cc Morris Minor. We were told that unleaded fuels required a different advance from the leaded fuels around when the cars were new.

In the end, all that we did was to set the engine at 3000 rpm and rotate the dizzy slowly each way until the revs 'Peaked'. We did the same at 2000 rpm and found that there was very little difference in the timing position.

We did this on two Minors. They ran smoothly, started well and gave over 35 mpg. These cars are still in use and have not ruined any big ends. It may be worth just doing this. You could play around for ever.

My 2.5 litre Vitesse does not seem to mind anything between 5 degrees BTDC and 5 degress ATDC. I will try this method on that come the Spring.

[NonMember]

59 minutes ago, cliff.b said:

It also looks like MGBs have a far more aggressive advance as standard than Triumphs and I'm wondering why that would be?

Aggressive advance curves usually indicate an engine that produces a slow burn. At higher RPM, slow burning mixture needs longer and hence more advance to reach peak pressure by TDC. Ultimately slow burn also limits the engine's revability, so most modern engines are designed for a fairly rapid burn.

[cliff.b]

10 minutes ago, NonMember said:

Aggressive advance curves usually indicate an engine that produces a slow burn. At higher RPM, slow burning mixture needs longer and hence more advance to reach peak pressure by TDC. Ultimately slow burn also limits the engine's revability, so most modern engines are designed for a fairly rapid burn.

That makes sense but I don't understand why the mg appears to use more advance when it uses what I would imagine is very similar technology and state of tune.

I'm sure there's a good reason lol

 

[cliff.b]

43 minutes ago, Wagger said:

In 2002, two of us were having bother timing a 1098cc Morris Minor. We were told that unleaded fuels required a different advance from the leaded fuels around when the cars were new.

In the end, all that we did was to set the engine at 3000 rpm and rotate the dizzy slowly each way until the revs 'Peaked'. We did the same at 2000 rpm and found that there was very little difference in the timing position.

We did this on two Minors. They ran smoothly, started well and gave over 35 mpg. These cars are still in use and have not ruined any big ends. It may be worth just doing this. You could play around for ever.

My 2.5 litre Vitesse does not seem to mind anything between 5 degrees BTDC and 5 degress ATDC. I will try this method on that come the Spring.

Yes, I may be overthinking this 🤔

[NonMember]

1 hour ago, cliff.b said:

That makes sense but I don't understand why the mg appears to use more advance when it uses what I would imagine is very similar technology and state of tune.

I'm sure there's a good reason lol

Similar technology, yes, but burn speed depends very heavily on port design, combustion chamber shape, and the like. I've not looked at a B-series to compare chamber shapes, though.

[Wagger]

Some of our motorbikes had manual advance/retard levers as late as mid 1960's. We 'Played' with them when riding. Some of us were almost sent over the handlebars trying to start them when we forgot to retard it before kicking it over.

Same on early cars with starting handles, many a broken wrist.

Actually, it does not look too difficult to fit his feature. Cable attached to the vacuum lever. (Vacuum disconnected and blocked).

Have any of you racers done it?

 

[cliff.b]

2 minutes ago, Wagger said:

Some of our motorbikes had manual advance/retard levers as late as mid 1960's. We 'Played' with them when riding. Some of us were almost sent over the handlebars trying to start them when we forgot to retard it before kicking it over.

Same on early cars with starting handles, many a broken wrist.

Actually, it does not look too difficult to fit his feature. Cable attached to the vacuum lever. (Vacuum disconnected and blocked).

Have any of you racers done it?

 

Yes, I remember my dad had that on his 1950s Norton & sidecar combo. Lever on the handlebars.

I did idly think about fitting similar to the spit. Could just fit a syringe into the dash & connect to the existing pipe lol

[cliff.b]

8 minutes ago, NonMember said:

Similar technology, yes, but burn speed depends very heavily on port design, combustion chamber shape, and the like. I've not looked at a B-series to compare chamber shapes, though.

Interesting stuff.

I can easily get to the point where trying to understand this stuff becomes more important than the original issue 😒

[Wagger]

You are absolutely correct. Many of my ideas have been remained 'In myhead'. Some get written down and drawn up, and about 1% achieve experimental form.

I do like your syringe idea. The Hillman imp originally had a pneumatically operated throttle. Hmm!

[cliff.b]

1 hour ago, Wagger said:

You are absolutely correct. Many of my ideas have been remained 'In myhead'. Some get written down and drawn up, and about 1% achieve experimental form.

I do like your syringe idea. The Hillman imp originally had a pneumatically operated throttle. Hmm!

Lol. Most of my ideas remain in my head which is probably for the best 🙄

[Pete Lewis]

3 hours ago, cliff.b said:

syringe into the dash & connect to the existing pipe lol

the vac advance unit only aids consumption when cruising on a light throttle  it has no effect on performance 

pete

[Wagger]

Pete is correct. There are many long articles available on this topic. We would need to fit an up to date engine management system to make timing correct across the whole rev range, Then, we would not be able to tinker!

Might just as well have a newer car. No fun in that is there?