xpndbl3

iTrader: (23)

What is a typical timing curve for a cam only car with a cam in the 230 duration range? I was thinking 18 at idle with it all in by 3000rpm with 26-28 total. Then is there 10 degrees or so of timing added at idle as well by the MAP sensor? Reason I'm asking is I'm running a msd 6010 box with a carb on top and wasn't sure of how a gen 3 motor compares to the gen 1 engines I've been used to tuning.

ryansm1

iTrader: (8)

The timing controlled by the PCM isn't really a "curve" (rather a surface, I guess), so your question is a little harder to answer.

I usually give between 20-25 degrees of timing at idle with cams around that duration. You can use lower, but I've found that the MAP decreased a bit with more timing (good for autos when using the brakes to sit still).

26-28 degrees of timing wide open seems to be standard. You'll need to play with the timing on a dyno to find what the engine likes.

Timing isn't added by the MAP sensor (directly). Timing is commanded based off calculated air mass, which is calculated from MAP input. When controlled by the PCM, the timing uses the base spark tables for idle conditions, and the main spark tables for non-idle (throttle or vehicle speed higher than the set parameter). At idle, I've been using 20-25 degrees. Wide open, I've used 26-28 degrees as the car requests. Between the two, it's less clear. Hope this helps.

xpndbl3

iTrader: (23)

That definitely helps, although for this msd 6010 box the only timing that can be added at idle or part throttle cruise is based off the map sensor. I wasn't sure for a part throttle cruise if I can add in for example another 10 degrees of timing and run 36 lets say at part throttle.

since it would be 26 at 3000 rpm plus 10 degrees off the MAP to give me 36 total for around town driving. On older engines the added timing would help with fuel economy and help keep plugs cleaner longer. Just wasn't sure if it also is needed on this type of motor.

Robin L

I like the 6010. I just used one on the dyno to take control of the timing from the PCM. I can now build the tables the way that I want.


Your correct with regard to low load timing. At no vacuum you want to have a max of 26 to 28 depending on your combination. At low throttle or higher vacuum you can put a bunch of timing in it. Decel timing will help keep the egt down and keep it clean.

Robin

xpndbl3

iTrader: (23)

How much low load timing did you add in typically, I'm just looking for a basic starting point here.

Robin L

I would play with that a bit. I would be at 32 to 36 for a low load.


You can try putting it up a bit but without a decent way to sense knock your going to want to be careful.

Better fuel, = more timing
Cooler temps = less timing

Good luck

Robin

xpndbl3

iTrader: (23)

Thanks I'll try hitting it with 32 total on low load and see how it likes it. Probably 26 at 3000 and add another 6 degrees with the map reading then