I just switched over to a 160° thermostat. I also switched to projected tip spark plugs.

Does anyone think these two changes will have an effect on how much timing I can safely run?

I kind of want to stay a couple steps away from the "edge". I can't afford to fix any major problems.

I ran an old carbed 502 mag at 35 degrees on 93 with never any problems...FYI Merc runs 36 degrees on 87 octane with their 500EFI's...

On Gen V 454mags and 502mags, the cams are exactly the same and have the same Merc part number 431-9830.

The stock ignition module for the 502 mag shows it as a V8-20R which really makes no sense. That module does not make full advance until about 5250rpms. Unless he is running at 5250rpms, he's really running even less total timing.

The 454mag uses a V8-24 which is at full advance at 3750rpms.

V6 module is best to run on stock system....timing is all in way sooner...like 3000. (can't remember for sure)

I checked the timing on my 502 running full tilt across the lake and it did in fact have the full 20° of advance in before 5000 RPM's. I do believe the published curve says it doesn't get it in that fast, but according to my timing light, it did.

My motors (496 Gen IV) 10 to 1, Canfield alum heads, run 92 to 93, 36 total. No problems at all...