base timing setting
Discussion
Suggest you don't go too low or too high... with a 460HP Street Ultima, I run 30 degrees total @ 3250RPM, with 18 dynamic and 12 static. Unless you have a very aggressive advance curve, or race set up, these should be fine to get you going, avoid the dreaded detonation and provide you with 97% of available power.
Tune as necessary from there.
Tune as necessary from there.
And another thing... if you have a mechanical MSD ignition
Static timing is not normally taken as static at all, but at idle revs (initial timing). ex ~850RPM for a fast road cam.
Looking carefully, you can see from the MSD ignition curves here www.msdignition.com/pdf/8365_frm%2026045.pdf that there is already some dynamic advance coming in, the amount can very significantly and is dependent upon the curve chosen.
As an example, at 850rpm you may be seeing 12 degrees inital timing on strobe but only 8 will actually be 'true static'; 4 is being added by the dynamic action of the centrifugal advance at that RPM.
It's easy to underestimate total advance and so set yourself up for detonation issues. Remember that when looking at the MSD timing curves, always add 'true static' to them, in order to estimate advance at any RPM and that this will change with different curves.
Adam.
Static timing is not normally taken as static at all, but at idle revs (initial timing). ex ~850RPM for a fast road cam.
Looking carefully, you can see from the MSD ignition curves here www.msdignition.com/pdf/8365_frm%2026045.pdf that there is already some dynamic advance coming in, the amount can very significantly and is dependent upon the curve chosen.
As an example, at 850rpm you may be seeing 12 degrees inital timing on strobe but only 8 will actually be 'true static'; 4 is being added by the dynamic action of the centrifugal advance at that RPM.
It's easy to underestimate total advance and so set yourself up for detonation issues. Remember that when looking at the MSD timing curves, always add 'true static' to them, in order to estimate advance at any RPM and that this will change with different curves.
Adam.
Edited by layada on Wednesday 21st June 13:52
Edited by layada on Wednesday 21st June 13:57
It can all get a little confusing!
My 525BHP AS engine documentation states 16Degrees@900RPM and 39Degrees@3000RPM. That is what I used to base my EFI timing tables from.
Also before taking my MSD stuff off I checked the timing with a strobe against the crank timimg tape, this confirmed the above figures (just). I say just as it was good at 900RPM but out at 3000RPM, still thats distributors for you!
Confirming the timing after fitting my EFI proved harder. Many timing lights on the market seem unable to pickup a good signal from my Ford type coil packs. I had to have a garage confirm it with a quality strobe.
My 525BHP AS engine documentation states 16Degrees@900RPM and 39Degrees@3000RPM. That is what I used to base my EFI timing tables from.
Also before taking my MSD stuff off I checked the timing with a strobe against the crank timimg tape, this confirmed the above figures (just). I say just as it was good at 900RPM but out at 3000RPM, still thats distributors for you!
Confirming the timing after fitting my EFI proved harder. Many timing lights on the market seem unable to pickup a good signal from my Ford type coil packs. I had to have a garage confirm it with a quality strobe.
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