msd 6 programmable for cis

[47silver]

2.7L with a 3.0 CIS fuel delivery and intakes, ported heads, slightly larger valves, same cams a little higher compression than stock. Would the engine benefit from a programmable MSD that i would be able to set up a custom curve? The mechanical distributor in the car now works and goes to full advance around 4000 rpm.

I am wondering whether a more linear curve would be better or perhaps one where the advance came in at around where the cams start to work better, say 3200 rpm then linear to redline to 35 btdc?

the msd should allow plotting a perfect curve to redline. Is this something that anyone has experience with in a cis application? Or should i just keep the setup I have which is a msd 6al with a 004 distributor?

[psalt]

If you have a correctly functioning early distributor and 6al, and no mid range pinging problem, the improvement would be subtle at best. The real benefit is the abiility to back out timing in a problem area, something no distributor can do. The knee in the timing curve is there to reduce the probablity of pinging when VE is highest at the torque peak. CIS runners and cams are designed to boost the low rpm torque peak and the curve was shifted down for subsequent compression increases.

[304065]

And I would add to Paul's comments, perfect curve based on what set of conditions? The motronic brain can use like 45 degrees of advance under lean no-load conditions. Even then there is still a mechanical advance in the distributor for rotor phasing.

The other limitation on using a programmable box is where you get your trigger signal from. Ideally you would have a crank trigger to eliminate the slop in the distributor.

[47silver]

thanks
may get one to see how it works, i would guess that it should work like a standard msd 6al, using the distributor as a trigger and advance.