Distributor timing

[Triumph TR]

I purchased a 1971 Traveller from a friend who said that his mechanic after performing work on the car (valve job) told him it needs a new distributor, and carb. Vacuum advance on the dizzy was bad. So I installed a power spark 45D dizzy. Guessing how to rough time it as it needed to be rotated to clear the vacuum pod from things on engine. No real instructions in the box or website about when the rotor and stator aline to fire. Engine started right up with rough idle but rev’d well. Plenty of smoke from tailpipe. Looked to be about 20-25 degrees BTDC in the strobe. Tried to set with strobe but doesn’t want to run when retarded close to 6 degrees BTDC. How odd. I suspect the carb is so bad it may be the issue, but I don’t want to tear it down until I have sorted dizzy out. Any ideas? Plugs fire 1, 3, 4, 2.

[svenedin]

Are you sure your strobe is on spark plug lead number 1? Not trying to be rude but I’ve actually made that mistake myself and have been very puzzled!

Distributor rotor rotates anticlockwise with leads in order 1, 3 ,4 ,2

It is possible to engage the distributor drive dog 180 degrees out but in that case, the distributor will not go fully home against the block. The drive dog is offset and will only go totally home in the correct position.

Standard distributor for a 1098 is Lucas 25D4. I tried an Accuspark distributor but I was not at all impressed. The micrometer adjustment is non-functional and I found it wandered on the strobe. In the end I had my own genuine Lucas 25D professionally overhauled. This guarantees the correct advance curve. Club spares have genuine Lucas 25D distributors for sale.

Stephen

[Triumph TR]

Yes I’m on the number 1 cylinder with the strobe. I had aligned TDC #1 with points just breaking before I pulled the old dizz but one thing about the electric ignition set up is I am unsure of where the spark fires in relation to the rotor and stator. I have written to Powerspark and awaiting a reply. Reasonably sure that I’m not off 180 degrees as the dizz it’s firmly seated against the block. The issue might be in the carb needing a cleaning rebuild but I don’t like to repair before I’m certain that I have distributor correct. Gets too confusing chasing multiple issues. I wish I could speak with the prior mechanic who did the head but there is some type of argument and no one is talking to each other.

[svenedin]

Ok. Remember you need to disconnect the vacuum advance pipe from the distributor and block the end of the pipe temporarily with a bit of insulating tape or similar. Then adjust the idle right down to around 600 rpm or ideally even lower if it will tolerate it. The reason for having the engine so slow is that the mechanical centrifugal advance will be operating at higher revs. Then set to 6 degrees BTDC with the strobe although you may find 8 degrees better (see graph). We do not know when the centrifugal advance starts to operate with this Accuspark distributor but with a Lucas 25D we do know and I attach an advance curve of my own distributor.

Many people advocate setting entirely by ear and advancing until the engine pinks when accelerating under load then retarding until the pinking stops. It's not the way I do it.

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[philthehill]

No two engines are the same so the same parameters cannot be applied for or to all engines.
You can set the ignition timing by prescribed methods but the final setting will be concluded by either road or rolling road testing.
Using the pinking test method is a a perfectly acceptable way of determining ignition timing.

[svenedin]

No two engines are the same so the same parameters cannot be applied for or to all engines.
You can set the ignition timing by prescribed methods but the final setting will be concluded by either road or rolling road testing.
Using the pinking test method is a a perfectly acceptable way of determining ignition timing.

Yes but it relies on the person being able to detect pinking and a lot of people can’t. I found that by using this method that according to the strobe my ignition was quite ridiculously advanced. It didn’t pink for months then suddenly it did on a long journey and that is not good. I’d rather be conservative and err on the retarded side of caution. My method is to set to the book value and tweak from there but only a few degrees

[oliver90owner]

No two engines are the same so the same parameters cannot be applied for or to all engines.
You can set the ignition timing by prescribed methods but the final setting will be concluded by either road or rolling road testing.
Using the pinking test method is a a perfectly acceptable way of determining ignition timing.

Yes but ….

Phil is right, spot on, and practical as usual. Even a change of fuel supply can induce pinking - as can incorrect fuelling (carb settings) - which may become apparent if the engine has some carbon build-up due to the mixture being wrong on a long journey at constant speed/power.

The old saying that ‘there is more than one way to skin a cat’ applies to these old, very basic engines.

[Myrtles Man]

The following extract from Staton Abbey's book about Triumph sports cars details the best way of setting accurate ignition timing:-

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[myoldjalopy]

Yes, he says pretty much the same thing in his 'Book of the Morris Minor 1000', but gives a bit more detail about different fuel grades and 'pinking'.

[svenedin]

The following extract from Staton Abbey's book about Triumph sports cars details the best way of setting accurate ignition timing:-

Scan_20230730 (2).jpg

Which is pretty much what I said isn’t it? Set to the book value and tweak by a few degrees. The OP has electronic ignition so he cannot set static, only dynamic. Those Accuspark distributors have a fake non-functional micrometer adjuster though and that is what the OP has.