6-hemi ignition controller: Anybody using one?
I am - and I have experimented with it.
First - Not only is the supplied curve fairly lazy - but the MAP curve is set up really weird.
This is important to understand - A MAP sensor or a vac advance on a distributors job is to add timing at low Man Pressure (Hi Vac) and slowly reduce to zero under WOT.
MSD have set this up so that as the Manifold Pressure increases under WOT, not only does the MAP advance drop off (as it should) - BUT it actually keeps dropping below ZERO -
This means the MAP is actually pulling timing out of your RPM timing curve under WOT. Which is crazy!
So here's the fix.
Step 1 - Change your MAP timing graph so that the line does not go BELOW Zero degrees.
The MAP curve is OK as far as how much timing it adds..and at what pressure it starts to reduce - Its just that it shouldn't go below Zero value.
Check these pics -
The 1st is the supplied MAP curve - note how it holds at 12 degrees added to your RPM timing and then starts to reduce as pressure builds - but THEN, it keeps going and starts to rip timing out of your RPM curve at 11 PSIa.
This is what it should look like - you don't want the MAP interfering with your WOT RPM curve at 11 PSIa and higher.
I am - and I have experimented with it.
First - Not only is the supplied curve fairly lazy - but the MAP curve is set up really weird.
This is important to understand - A MAP sensor or a vac advance on a distributors job is to add timing at low Man Pressure (Hi Vac) and slowly reduce to zero under WOT.
MSD have set this up so that as the Manifold Pressure increases under WOT, not only does the MAP advance drop off (as it should) - BUT it actually keeps dropping below ZERO -
This means the MAP is actually pulling timing out of your RPM timing curve under WOT. Which is crazy!
So here's the fix.
Step 1 - Change your MAP timing graph so that the line does not go BELOW Zero degrees.
The MAP curve is OK as far as how much timing it adds..and at what pressure it starts to reduce - Its just that it shouldn't go below Zero value.
Check these pics -
The 1st is the supplied MAP curve - note how it holds at 12 degrees added to your RPM timing and then starts to reduce as pressure builds - but THEN, it keeps going and starts to rip timing out of your RPM curve at 11 PSIa.
This is what it should look like - you don't want the MAP interfering with your WOT RPM curve at 11 PSIa and higher.
