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MG TD TF 1500 - ignition timing setting TF 1500

I have been told by some that with today's higher octane gas than years ago timing should be advanced to about 12 degrees btdc? Reactions? I have a Pertronics electronic ignition system to if I were to advance the timing at idle would it throw off the advance at higher RPM?
TF 1500
Robert Weinstein

I think the best way to do it is in steps. Start with 5degr BTDC and you should notice a bit more pep. If no pinking / pinging then try 10degr BTDC and compare. Check for pinking / pinging again. I think that 10 is enough to be safe.
Dave H
Dave Hill

The pertronix LU series Igniter acts as a set of points for timing. It's not designed to affect ignition timing with engine speed. There's a good bit of thought that proposes that an advance of about 30° at 3000 rpm is a good setting for today's fuel. How much of an advance that is in a static condition will depend upon your distributor. Bud
Bud Krueger

Bud
thanks. I had the points replaced by a shop before i even looked at them. I though the original had weights or vacuum advance. How would that occur with electronic?
robert
Robert Weinstein

The Petronix does not replace the weights.
L Karpman

I agree with Bud. The advance weights are below the plate where the points or electronics are mounted. The weights will still advance the spark as revs rise, whether or not you have an electronic device.

If you mean 12 degrees STATIC, that sounds too much to me. I think that could result in about 42 degrees at high revs!!! (depending on your dizzy advance rate). 12 degrees at IDLE is a different matter .... That might result in 30 degrees at high revs, which might be about right. Note ... An engine with a high compression ratio (or supercharger) will need LESS advance. Too much advance can damage a motor.

Bob Schapel

R L Schapel

Robert, some electronic ignitions control spark advance with engine speed. The Pertronix LU series just fires the spark at the same point of rotation of the distributor cam. This also holds for their LS series, where LS=Lobe Sensing. It's still the 'below the plate' parts that Bob mentions that control the spark timing. I seem to recall that a static advance of about 5 degrees is more like it. Bud
Bud Krueger

An engine with not enough advance can damage an engine by overheating it.
D mckellar

The timing required depends on several factors including how the engine is tuned and the type of fuel you're running. Timing is ideally set at higher RPMs since this is where the engine will be under load and therefore where it matters most. I like to check timing at 3500+ RPMs and then check idle after that. If the idle is anywhere near where it should be then I'm happy. If not then the distributor should be re-curved.
Steve Simmons

An engine with too much advanced timing can be damaged, engines, fitted with vacuum advance distributors, in a high state of tune it is recommended to disconnect and seal the vacuum line.

Graeme
G Evans

Informative thread. After over 60 years, no two engines are exactly the same, given different CR's due to head thickness & re-bores, valve replacements, as well as cam upgrades, so does anyone know of a chart that might indicate the desired degree of appropriate advance? Or are there just too many variables to make such a reference impractical? Cheers
Peter TD 5801
P Hehir

http://www.ttalk.info/Tech/Advance_curves.htm shows the OEM advance OEM curves for most of our distributors. There's been a lot of talk of raising the 3000rpm advance to 30° for modern fuels. Bud
Bud Krueger

This thread was discussed between 20/02/2017 and 23/02/2017

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