Morris Minor Owners Club

Be very grateful if anyone could let me know the dynamic timing advance curve for 1300 marina engine?

The manual gives a static figure of 9 BTDC, but that's all.
I'd like to check it with a strobe.

thanks,
Chris

What number is stamped on the baseplate of the dizzy?

Thanks for the reply...

Be tomorrow at soonest before I can check that out.

regards
Chris

This is a direct quote from Roy (bmcecosse)
To get this - you need to open up the dizzy and see what number is stamped on the 'nose' of the plate that moves with the balance weigh. It may eg read '13' - which would give 26 degrees of dynamic advance. The general 'ideal' overall advance for a good A series is ~ 36 degrees advance - but 10 degrees static is too much for the starter. So - To get more dynamic advance - you could cut/file about 1/16" off the end of the 'nose' - then reassemble and try again. Of course if you get any pinking you would have to reduce the static advance slightly - you must NOT have pinking! If it still seems to GO better when you advance it (but get starter kick-back) then again take another 1/16" off the nose. Just go carefully - and don't take too much off. It's a trial and error process.

Some Marina engines had no vacuum advance unit fitted - supposedly to prevent 'crankshaft rumble' - which seems highly unlikely to me! If your dizzy has no vac unit - you would be well advised to get one!

Hello Chris,

if you can quote the Lucas number stamped on the side of the distributor, I'll see if it is on my list of distributors and I can tell you what it should be. What PSL advises will give the total mechanical advance only, not the curve.
The other point about the vacuum unit is that it needs to be matched with the fuelling on a non standard engine.

Alec

Well,
got the number off the side, by taking a rubbing, because I could not see it as the oil filter canister is right in the way!

As far as I could make out it is 23D and underneath 41372
It is possible that there may be other characters after the above, which I could not get

Also, Roy, it does not have a vacuum advance.
The pipe on the side of the carb, to which the vacuum tube would connect to is utilised by a breather tube from the timing chain cover.

regards
Chris

23D4

High compression engine. That also tallies with the number 41372 underneath, also being for HC

Hello Chris,

The advance curve for that distributor is :-

2500 rpm min 9-11 degrees, 1400 rpm 5.5-7.5 degrees, 800 rpm 2-4 degrees, 150 rpm no advance below that.

Note these are distributor rpm so half engine speed. No vacuum advance is correct for this unit.
Unfortunately my list doesn't give the application for the specification?

Alec

Hi Alec,
If I may jump in, can you give me any advance curve info on a DKYH4A 40251F. There are no numbers on the bob weights and no vacuum advance. I can then compare it to a 25D and see if I can improve the engine performance.

Hello Mike,

very similar, :-

2,700 9-11, 1000 4.5-6.5, 450 0.5-2.5, no advance below 175

Hope that helps.

Alec

Thanks, now all I have to do is work out what to do with those figures.
Wasn't there a website with distributor applications?

Alec,

many thanks for those figures!

Much appreciated.

Chris

That advance sounds hopelessly low - as I pointed out on another thread - a 'good' A series wants ~ 36 degrees of total advance - and for good idling/acceleration and economy you MUST have a vacuum unit. I suggest you buy a complete 45D from simonbbc or 'accu-spark' and fit that. The vacuum advance does NOT go where the breather is connected to the carb!

Hello BMCE.

"and for good idling/acceleration and economy you MUST have a vacuum unit"

I don't believe that is quite accurate, it has little effect on idle or accelertion but is benefitial to economy if the engine is adjusted leaner at cruise. As Mike earlier query highlights, earlier distributors did not have vacuum advance, but the introduction did have an economy benefit.
Many of the queries here refer to modified engines so it is misleading to say that the vacuum advance is essential. Benefitial yes, if the correct needle is selected, but it does make the tuning more complicated.

Alec

Without the vacuum unit - the static advance needs to be excessive to get good idling - having the vac unit allows nice low static setting (2 or 3 degrees = easy starting) - and as soon as the engine fires - the vac unit pulls up the timing to give good smooth idling with something like 12 degrees advance. It also aids initial acceleration - by holding the engine at decent advance levels - as the accelerator is pressed (to accelerate !) the manifold vacuum starts to collapse of course - but the tube to the dizzy is tiny - and just for a second or so the vac advance is held up - helping the initial acceleration - then the mechanical (centrifugal) advance takes over as the revs increase. I can assure you - when my vac unit was not working - the engine was flat as a pancake! Now - when I accelerate - there is just a second of 'light pinking' as the engine picks up - this then stops and the engine roars (!) away! Well - as much as a 1098 can 'roar' !
Seriously - I urge all to have working vacuum units - you won't regret it!

Hello BMCE,

yes, up to a point but the carburation is matched to the vacuum advance, they cannot be separated; it is by no means a universal feature on all engines. You may be being specific to the Minor, and if the engine is standard then it is sensible to have the correct vacuum unit, once it is modified well it's another variable to set up.

Alec

I am assuming from what you say, Roy that the 45D is a replacement from the 23D?

In the Marina manual there is mention, when removing the dist "remove the vacuum pipe (not 1.3 engine)"

regarding the pipe fitting on the carb, there are 2 breathers. The crankcase goes into the air cleaner case and the timing chain cover into the side of the carb, in the same location as does the vacuum pipe on my Traveller...So If I did fit a new dist with vacuum, where would the pipe go into the carb?

The vacuum pipe should go to a very small connection either at the engine edge of the carb - or sometimes a connection is provided in the manifold itself - or in the black plastic spacer twixt carb and manifold. And yes - a 45D is the much improved later dizzy that will slot into your block - and comes with the vacuum fittings.[frame][/frame]
#6 here is the breather connection - and would be useless for a vacuum advance! If the carb has a vac connection - it would be a small pipe standing upright just above the 'arrow' pointing to #6. Some carbs don't have it - hence the need for the plastic spacer with connection - if the manifold doesn't have it.

Roy,

many thanks for the photo & information!
It does sound like the way to go especially since the price of the dizzys is so good.

It's now dark & raining here (tourer lives in a car port) so I will have a look as soon as I can for this elusive pipe.
Can't think that I've seen one though, so I may be able to fit a pipe into the spacer, if need be.

regards,

Chris