Ransomes MG5 – My latest project!

[vhgmcbuddy]

Still no luck getting it running. 🙁

I have a spark at the plug and fairly certain the fuel situation is OK.

I have noticed that the impulse is clicking between 20deg and 3deg before TDC. No matter how I adjust the magneto it would seem when turning over it clicks at 20deg BTDC. Am I doing something wrong? As the book states it should click at TDC for starting…

Perhaps the chain has slipped?

[ransomes256]

James,
The magneto should click every time at TDC.
It will spark (click) on both the compression and exhaust strokes.
You need to check the engine timing. ie are both inlet and exhaust valves fully closed at compression TDC. The timing chain can jump teeth if it has become slack.
If this is OK try some easy start.
Neil

[vhgmcbuddy]

Hi,

The plug is sparking every time the magneto clicks. And every time 20deg before TDC. Is it possible that I have reassembled the magneto incorrectly? At TDC the teeth on the magneto dog where in the horizontal position.

What is the best procedure to taking the engine apart and checking that the timing chain hasn’t slipped?

This could be interesting…!

[ransomes256]

James,
The dog on the magneto can only fit in one of two positions and it is unlikely this was wrong. I am assuming it is the correct magneto and was not a rouge version in the first place.
It should be an A-1009-CZ
The quickest and least intrusive check is to take the tappet cover off and check you have maximum valve clearance at compression TDC the timing chain drives the camshaft which also drives the magneto.
Neil

[vhgmcbuddy]

Hi Neil,

Great. I will investigate.

In the meantime, I think I’ve had a bit of a lightbulb moment…!

Looking at some literature for the MG5, I think my ‘assumption’ of TDC may have been inaccurate.

I had a screwdriver down the plug hole and was claiming TDC when the screwdriver was at its upmost.. It has just occured to me, that what I thought was the piston may have indeed been the valve, hopefully meaning the timing chain is OK..?

[vhgmcbuddy]

Ok. I am now suspecting this is a fueling issue.

Can someone advise how I remove and check the emulsion tube from the Amal 356? I’ve changed the jets, but seem to get a small flood of petrol coming out the carb inlet.. Suspect blocked emulsion tube..

[ransomes256]

James,
The emulsion tube is located under the blanking plug on top of the carburettor. Once the plug is removed there is a wide screwdriver slot in the top of the tube. If this has been butchered there are only 3 options.
1. Try to improve the slot with a Dremel type tool.
2. Try to use a screw thread easy out.
3. As a last chance drill out and replace the tube.
You may need to use some heat for options 1 & 2 but be careful of any retained petrol.
Once out the tube should not be split and have 2 cross drilled holes and a solder plug in the end.
If you have not previously had this tube out I doubt the internal cross drillings in the carburettor body are clean.
Neil

[vhgmcbuddy]

Hi Neil,

This tube has not been out. However I have tried to remove it. Should it simple unscrew? The slot is OK, but perhaps the thread is damaged. As it wont come out.

I will investigate this first. 🙂

[ransomes256]

James,
It is a fine thread and should just unscrew. However, It may have corroded so would need care and as I stated previously some heat. Take care not to melt the aluminium casting.
Neil

[vhgmcbuddy]

Hi Neil,

Sorry to be a pain, but is the orientation of the emulsion tube critical? I.e. Should the slot be in line with airflow?

Regards

[ransomes256]

James,
The slot is random and has no bearing on tube.
If anything the internal passages need cleaning.
Neil

[vhgmcbuddy]

Hi all,

Can anyone tell me what capacitance value I should read across the capacitor.

And, presumably I should be able to see the points spark on the magneto, as per a distributor?

Another query relating to the Amal carb. With the air induction pipe off, and the emulsion tube removed. If you look down the venturi with the choke open you can see a brass collar protruding up into the venturi by what looks to be just under 10mm. Is this normal? The emulsion tube inserts inside this. Should this be tapped down flush? – what is it?

I seem to just be getting a ‘river’ of fuel in the carb and inlet manifold, which is not helping.. Any thoughts? Perhaps this is perfectly normal..

[adam4472]

Hi, we have a MG5, 1949 petrol/TVO, with a small petrol tank mounted near the seat, inboard of the silencer, have seen some with the petrol tank mounted on the front of the engine cowel. We have not had ours running for a while and it also has the Amal carb like yours, it starts fairly easily, but doesn’t like running slow enough for clean gear selection.
Will download some photos later.
Adam.

[expeatfarmer]

Valve clearance, points gap, ignition timing and slow running mixture all have an effect on slow running. Make adjustments to one item at a time until you achieve the ideal tick over for gear selection. As a matter of course run the engine for at least five minutes after starting to warm it through before you try to select gears it makes a big difference.

[vhgmcbuddy]

Hi Guys,

Thanks for the advice. My MG5 is still proving extremely extremely tricky to start.

We don’t have a fuel problem, more of an intermediate weak spark issue. I’ve replaced the points and condensor in the Mag and set it all up as per the book but still no joy. I now suspect there are some internal issues within the Mag..

I need to find a of measuring its exact output voltage before I fork out for an overhauled one, as my voltmeter maxes out at 1000V.

Can anyone recommend a company in the UK that can sell me or provide an overhaul service for my mag?

Thoughts please.

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