Originally Posted by
white2001s10
These are all my opinions here:
The hardest part will be getting a decently smooth idle, so of course all the idle tables apply, including idle speed & spark, etc...
A cam like that generally moves more air through the system, but traps less in the cylinder... meaning lower cylinder pressure and more misfires.
To an extent, the idle speed can be raised to counter-act this, but keep in mind that simply raising the idle speed way up is actually the LAST thing you want to do.
When you use other means to smooth and strengthen the idle, you don't have to raise the idle up as much, and all is better this way.
Running closed loop will make fueling at idle very difficult to get right. Stoich according to your narrow-band O2's is not going to be what the engine wants at idle. A wideband is more helpful, but here still it's not 14.6:1 AFR that is going to give you the best/strongest idle with a cam like this.
Open-loop (OLSD) tunes are best suited for taming camshafts like this, because you're not fighting against a fueling correction system that's trying to get 14.6:1 AFR in the exhaust... without actually knowing the AFR in the chambers.
Generally the idle will want to be leaner than 14.6:1 on your wideband... maybe even as lean as 15.5:1 (every engine is a little different).
Generally the spark at idle will want to be increased by quite a lot.
Where 16* works well for a stock or small cam, this cam may want 26* or more at idle.
Even in open-loop, there is an idle control & learning routine that you'll have to work around. This routine isn't expecting big fluctuations in idle speed to be normally happening, so keep that in mind. The routine tries to compensate for fluctuations in idle speed, and in doing so there is often overcompensation that make the fluctuations even worse.
One way to reduce this is to reduce the amount of change this routine can excercise.
Less IAC movement is better than more.
Less degrees of spark correction (overshoot & undershoot) is better than more.
The fewer changes that the software is able to make, the smoother the idle will be.
The MAP (vacuum) reading will not be steady with this camshaft, and this will aggravate the idle fluctuation due to the changing fuel delivered.
If fueling values are changing from 35 to 45 to 50 back to 35, then your fueling is obviously not very steady and will cause idle problems.
Find out which load (VE/fueling) cells that you're hitting during idle. Scanning/datalogging will show you this.
You'll need to work on this area to smooth the fueling out.
Some people make all the numbers the same and others just reduce the difference in nearby cells.
This should get you started.