Thanks for the explanation, I can see the logic now...
Many thanks,
Ron.
Ignition advance feedback
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bobtail84
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Just to add some info...
If and when you play with the spark map it will affect the fuel map and V/V.
The spark map I've posted is the one that I use with this fuel map. Normally you find a good spark map then work on the fuel map by data logging. If you have a hairy cam high Deg's on tickover are needed to give a smooth tickover, less Deg's on a standard setup. I've also got LPG on my motor and the spark map is different again, like this..
With LPG you need more advance at lower RPM but when you rise over 2500 RPM you need to retard the spark.
The numbers on my first spark map are + 10Deg because EDIS is set at +10BTDC so RV8 Static timing = 10 degrees BTDC
2 to 6 degrees @1200rpm
17 to 21 degrees @ 2800rpm
16 to 22 degrees @ 4600rpm
These numbers assume minus static (i.e 22 + 10 = 32)
IIRC the vacuum unit on the lucas dizzy’s was 10 degrees ………. So it safe to assume a total of 10 degrees max vacuum advance (giving 32 degrees on WOT and 42 degrees on a closed throttle @ rpms above 3200 ish.
As there is no mechanical advance with EDIS or MegaSquirt you have to add the numbers.
HTH
jeff
If and when you play with the spark map it will affect the fuel map and V/V.
The spark map I've posted is the one that I use with this fuel map. Normally you find a good spark map then work on the fuel map by data logging. If you have a hairy cam high Deg's on tickover are needed to give a smooth tickover, less Deg's on a standard setup. I've also got LPG on my motor and the spark map is different again, like this..
With LPG you need more advance at lower RPM but when you rise over 2500 RPM you need to retard the spark.
The numbers on my first spark map are + 10Deg because EDIS is set at +10BTDC so RV8 Static timing = 10 degrees BTDC
2 to 6 degrees @1200rpm
17 to 21 degrees @ 2800rpm
16 to 22 degrees @ 4600rpm
These numbers assume minus static (i.e 22 + 10 = 32)
IIRC the vacuum unit on the lucas dizzy’s was 10 degrees ………. So it safe to assume a total of 10 degrees max vacuum advance (giving 32 degrees on WOT and 42 degrees on a closed throttle @ rpms above 3200 ish.
As there is no mechanical advance with EDIS or MegaSquirt you have to add the numbers.
HTH
jeff
