Fitting new 1275 distributor – space for vacuum unit?

[Oldmogman]

Does anyone know whether a 45D distributor with vacuum advance will fit an early Marina engine?

Several people on this forum suggested replacing the standard 23D distributor (which has no vacuum advance) on my early Marina engine with a new 45D, which does have vacuum advance, to improve running.

However, when I looked at the engine, it occurred to me that the oil filter on the Marina engine sits where the vacuum unit would need to be.

I know the 45D was fitted to later Marina engines which have their oil filters in the same place as mine, so perhaps the 45D has its vacuum unit in a different position to that of the 1098 engine I was comparing it with?

Suggestions please!

[Alec]

Hello OMM,

is the 23D the original distributor? If so and it had no vacuum advance then the carburation would have been set up for that. To gain any benefit from a vacuum advance the needle (and spring?) in the carburettor would need to be changed.

A 45D with vacuum will fit, but will need to be orientated to fit which will also mean altering the drive spindle so the timing is correct. Do be sure you get the right 45D for a Marina engine.

Alec

[bmcecosse]

Yes -the 45D with vacuum will give up a very useful improvement - and it will go in - just swap the leads around if necessary. Any needle calibration/advance curve/vacuum advance spec etc depends very much on the fuel used - and today's fuel is a very different beast to that used 30 years or more ago! So - just install the dizzy - set it all up (ie advance and carb settings) for best idle - then run the car and listen for any pinking. If pinking - you must retard slightly - if none - advance until it does pink just slightly - then retard again until it's 'not quite' pinking. Then do a plug check - you are looking for a light beige colour.

[Oldmogman]

Thanks guys, that's great.

Alex - the whole carb has already been swapped! It's running an HIF44 and used to run fine with the standard 23D - until the advent of Mickey Mouse petrol.

BMCecosse - seems you really know you your stuff about the A-series and Minors in general; I see your posts all over the site! I would guess you're probably a mechanic/engineer?

Anyway, I'm now talking to BBC about a new 45D mapped to the engine and coil.

In the meantime, I have to track down a vacuum pipe. Would a Minor one (with the litte chamber halfway along) fit OK?

cheers

[bmcecosse]

The little chamber was abandoned many moons ago........ just use a rigid plastic pipe - obviously soft pipe (like washer tubing) won't do because it will just be squeezed flat by the air pressure.......

[Alec]

Hello OMM,

here's a link for the materials you require:- http://www.holden.co.uk/displayproduct. ... de=030.015

I would repeat that if your carburettor was right for the 23D, then a 45D with vacuum will need some tuning to get any benefit from it.

Good luck and let us know how you get on?

Alec

[Oldmogman]

Thanks Alec

Good call - hadn't heard of Holden but they've got some good stuff there.

As for carb tuning, is this a case of checking the mix with a Colortune and/or monitoring the colour of the plugs, and adjusting the main jet accordingly?

It's currently running with a BDL needle, but I also have a BAZ which I'm told is richer.

Cheers

[Alec]

Hello OMM,

not quite as easy as that, unfortunately. The only real way is to run the car on load and monitor the fuel\air ratio.

The needle will need to be tailored to allow for the weaker mixture that the vacuum advance will allow the engine to run on. If you can check what needle the later 1275 engines used with the 45D this should give a reasonable base to work on, assuming your engine has not been otherwise modified? Basically the vacuum advance feature allows a weaker mixture to be burned as the extra advance gives the correc timing for a weaker mixture.

Alec

[bmcecosse]

Certainly forget the 'colourtune'! Any change to the engine specs will require ignition and mixture adjustments... Just optimise the idling and then run the car listening for pinking - and then look at the plug colour after a good hard run.