Do different Cams require different ignition timings?

 

well yes & no
most cams especially the bolt in type are mostly run std timing on the ignition
does this mean it is optimum?
timing is affected by more than cam choice
for one is fuel quality. i run retarded cam timing and i have to run less ignition lead and that changes with seasons, the reason i removed the rivets and use screws on the timer plate so i can get to the switches.

 

No, timing is where the plug fires in relation to the position of the piston.

 

I always understood that it was not an issue but noticed that the maps for an SE204 have different timing tables than say a SE255 for example. As long as you have the proper map, timing changes are taken care of, but if you have a none Harley cam and use an HD tuner you would have to make changes manually. On that note I assume smart tuning will not change timing?

 

some performance cam combo's can benefit from ignition,timing adjustments. to say NO as a blanket statement if false. none of the auto-tune functions that i have ever seen will advance timing, if needed some will retard the timing if it senses a knock event. ignition timing adjustments on a modern fuel injected engine are best accomplished on the dyno (faster), although it can also be done with data-logging.(slower) also with the data logging method, if one of your adjustments is too far away, it can take a long time to get back to a good spot then refine it.
if you have a very mild bolt in cam with no compression increases, it''s probably not a big issue, anything with increased compression begins to need much more attention.
marco

 

Camshaft duration is a factor as well as is compression. A large duration cam that has poor cylinder fill at idle and turns on later will require different timing that a small cam that has a fast fill and poops out early. But these cams are typically found in different combinations.

The best answer is that the timing depends on the entire engine combination cam, piston & combustion chamber shape, stroke, compression, exhaust, etc.

When picking a map, one of the most important things to look at is opening and closing events of valves because the pressures in the intake based on those parameters is a key part of the map.