Timing Curve on 360 in an RV

LOL.... Agreed AJ. But I think we have the OP's situation, and Mopar73340's situation, which Mopar73340 thinks is the same setup with the same equipment, and is displaying the same symptoms. So for now, let's assume we are working as such: same setup and same problem.

So now to re-wrap our heads around this particular setup, which is the Edelbrock Pro Flo 4. OP, can you confirm that you are suing this system?

SO that system comes with a new distributor with a sensor in a fixed spot and no actual mechanical advance mechanism, or vacuum advance pod. Everything related to spark is simulated.

One thing to realize about this type of spark triggering system: It really does not set spark from each trigger from the Hall Effect Sensor. It cannot accurately fire a spark in advance of a sensor trigger event that it is waiting for LOL. It can only detect RPM, use the average timing of the sensor triggers in absolute time, and compute a timing in advance of when it THINKS the next trigger will occur.

The random jumping around of the spark timing at idle observed by Mopar73340 is certainly a problem. Mopar73340, can you tell us by how much this timing jumps around, and does it jump retarded, or advanced, or both? This is interesting as it can effect completeness of burn, and if a lot of variation is there, why could it not add to the programmed advance and make that supposed 22* max advance jump way up into the 30's of degrees from time to time? Or a 30* timing jump to 40*? The 'why' sounds like it is one of the things that Mopar73340 has asked to the Tech Support folks with no good answers.

BTW, Mopar73340, how far toward NoVA do you live? I am near Waynesboro, and it would interesting to put my oscilloscope on this system and see if the triggers are varying in time, or if the program's timing accuracy is causing the spark timing jumps.

Also, if you take out the vacuum advance programming, does the jumpy idle timing settle down any? Just trying to think what else within the programming that could effect the timing.

And finally, FWIW.....this system is capable of flows to support 800 HP on 500 CI engines and big cams, per the setup instructions. Put this on a smaller engine and with a mild cam, with very low relative fueling requirements, and no one should be shocked that it will not have the best fine fuel control at idle and low cruise situations. I know someone who put a Holley Sniper system on a 2.2L 4 banger; it is acting the same with not the smoothest idle. (No reports on any timing variations, however.)