ignition timing

[Jimbo]

daft question
i know my 260 is supposed to run 10 degrees btdc but is that with the vacuum advance connected or disconnected?
plus now that i am using lumanition electronic ignition will it still need to be set the same as when it was on points?
there was no reference in the instructions so I'm assuming that it will still be the same

regards

james

 

[jonbills]

Yes, It'll be the same, but not sure about the static advance.
I'd advise to set it for peak advance of about 34 degrees and the idle advance will look after itself.

 

[Fairlineguy]

Timing will be the same and the vacumn pipe should be removed.

 

[Jimbo]

Yes, It'll be the same, but not sure about the static advance.
I'd advise to set it for peak advance of about 34 degrees and the idle advance will look after itself.

is the peak advance of 34 degrees set at a specific rev range? ive searched the forum and 3000rpm keeps cropping up?

 

[jonbills]

Yeah it’s around 3k rpm. A bit over I think.
If you want to change when full advance happens you have to change the springs governing the advance weights (of swap to something electronic)

 

[johnymd]

The subject of ignition timing and the ideal point to start the burn process interests me but I’m still no expert on the subject.

On a zed engine it has generally been found that 34deg advance at distributor full mechanical advance (3-3.5k revs) is a good average figure to be both safe and give good power. With a distributor this is pretty much all you can do.

If you go mappable ignition then you are no longer restricted by the mech advance system in the distributor. On my silver car I still run around 34deg at 3.5k but increase to to around 38deg at the higher end of the Rev Range. I also blip the advance between 1 and 2k to assist pull away. Install some knock control or monitoring and you can really push the limits and get the maximum drivability/enjoyment from your toy.

 

[Jimbo]

Yeah it’s around 3k rpm. A bit over I think.
If you want to change when full advance happens you have to change the springs governing the advance weights (of swap to something electronic)

and thats still with the vac pipe removed?

 

[jonbills]

Yes thats right.

 

[Jimbo]

cheers everyone

 

[johnymd]

The vacuum advance is for drivability and economy. It is usually disconnected on a race engine as you are not bothered about this but should be used on a road going car. It modifies the ignition advance based on throttle position. Throttle wide open = no advance. Cruising and idle will give full vacuum advance. When you are setting the mechanical advance of 34* at 3.5k revs you are interested in an on load/full throttle setting so you don't want the vacuum advance interfering with this which is why you disconnect it to set the "all in" advance.

Hope this helps.