Declan's timing marker

[Mark Wilson]

My rebuilt Midget 1275 engine starts and runs, but on very approximate timing and carb settings. I'll shortly be trying to improve on these, using a strobe for the timing (although it will still need refining once I can road test), so I decided to have a go at fabricating a "top view" timing marker as designed by Declan (he's seems to be taking over my car, I've already got his trunnion seals and clutch linkage!)

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So I cut and bent aluminium to his design, printed out his graphics (after adjusting the scale to get the correct size), laminated it and stuck it to the ally. Quite pleased with the result, until I tried to fit it. Aargh - can't be done with the engine it situ, unless you are more inventive and flexible than I am.

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So this is my modified version, lengthened and bolted to a front engine plate bolt instead of the timing cover. Given the choice I'd use the original design, but unless the engine comes out, and probably the damper pulley removed, this is a reasonable work around. Not easy to photograph in situ, but this should give an idea of where it is now fixed.

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Thanks yet again to Declan for a very good bit of design work.

Mark

[King Kenny]

That brilliant. I am going to make one tomorrow.

[Mark Wilson]

Declan's design drawing shows timing for a 1275 Midget engine as 7 deg BTDC static and 22 deg BTDC dynamic using a strobe. Can anyone suggest what revs the engine should be set at for the strobe setting? Searching the internet brings up Midget owners who talk about 32 deg at 4000 revs - don't think I want to rev a rebuilt engine like that!

[philthehill]

The static ignition timing for a MG Midget 1275cc engine is 7 degrees BTDC.

The dynamic ignition timing for a MG Midget 1275cc engine fitted with a 23D4 distributer is 22 degrees BTDC at 1200rpm with the vacuum advance disconnected.

The dynamic ignition timing for a MG Midget 1275cc not fitted with a 23D4 distributer is 13 degrees BTDC at 1000rpm with the vacuum advance disconnected.

[liammonty]

Declan's design drawing shows timing for a 1275 Midget engine as 7 deg BTDC static and 22 deg BTDC dynamic using a strobe. Can anyone suggest what revs the engine should be set at for the strobe setting? Searching the internet brings up Midget owners who talk about 32 deg at 4000 revs - don't think I want to rev a rebuilt engine like that!

As Phil says, there are settings that you can make at lower revs! The figure at 4000 rpm is useful because it will confirm that you're not getting too much advance under those conditions - beyond 32 degrees will likely cause issues, and although the timing should not advance beyond that if set to the specified values at lower revs, if the distributor is worn and giving too much advance, you won't know without checking at high revs. In addition to my British cars, I also have an air-cooled VW, and those engines are extremely sensitive to too much ignition advance (which leads rapidly to melted pistons and dropped valves) so it's a test I do on that to be on the safe side. Agree it isn't wise on first start up of a new engine though!! And I think Declan's timing marker is brilliant, but as I am lazy, I made a simple mark to indicate TDC that's visible from above the car, and use a timing gun with an adjustable timing dial, so I've no need for the marker.

[Mark Wilson]

Thanks for the helpful comments. I've a 25D 41270B which I rebuilt with new springs from the distributor doctor and a new vacuum unit from ebay Can't remember where I got the information that this was the correct distributor for a 1275 CE engine from.