Hi, got my 1200hp Fitech dual quad running pretty well after changing fuel pressure regulators and swapping to higher flowing fuel pump. Now I'd like to fine tune my ignition to as good as possible before I can get to dyno. I'll try to write everything I've done so far here, so my questions make more sense.
Parts:
The settings that I can change are like this (copied from FiTech manual):
Idle Advance = The spark advance desired at idle. (My current setting: 15)
1100 45kPa = Spark advance used just after throttle opens from idle. This value shouldn’t be much more than the Idle Advance, for this reason. (My current setting: 19)
3000 45kPa Cruise = Spark Advance used in a light cruise at 3000 RPM and throttle barely open. (My current setting: 24)
6000 45kPa = Spark Advance used in a high free-rev condition, perhaps also seen when autocrossing and just tipping-in in a low gear at high RPM. (My current setting: 29)
WOT 1100 95kPa = Spark Advance at low RPM and “full load” – perhaps the throttle is as low as 20% to see this much load. Spark is based on MAP, and MAP (and thus “load”) can get pretty high even with low throttle openings at low RPMs. (All of these are exactly same as 45kPa ones)
WOT 3000 95kPa = Spark Advance at high loads and 3000 RPM. This could easily be deemed “total” timing when comparing to a distributor, but due to the flexibility of a 3×3 matrix, this doesn’t limit you as such.
WOT 6000 95kPa = Spark Advance at high loads and 6000 RPM. At high RPM, some engines require more or less spark advance than at 3000 RPM. This allows you to set the timing there.
Parts:
- FiTech 1200hp Dual Quad system
- MSD 6AL box
- MSD Pro billet distributor locked up
- Small Block 408 stroker
- Comp Cams XE285
- Wiseco 10:1 pistons
- Some Edelbrock aluminium heads, I didn't build the engine so sadly not 100% sure
- Verified the TDC markings
- Installed Phaseable Rotor and phased it according to FiTech manual
- Set the FiTech "Base Distributor Degrees" to 10 and verified that timing light shows the same when timing is locked
- Set the timing drift @ 4000rpm to FiTech according to timing light
- Idle is smoothest at 19 degrees, but starts to kick back while starting when cold. Good compromise seems to be ~16 degrees
- Going over 30 degrees on higher RPMs starts to backfire in exhaust. I think that I originally had ~29 degrees in both 3000 settings and ~35 in 6000. The car didn't want to rev over 3000rpm at all.
- Now I've dropped my timings to 15 idle, 19/1100rpm 24dg/3000rpm and 29/6000rpm. Feels a lot faster than with my out of tune carbs at lower rpms, but it still hesitates at around 5500rpm, when with carbs I was able to rev to 6500 with no problems. AFR is fine, so completely ignition related.
- Are those numbers low? I've seen many threads with people talking about 35+ degrees of advance. Should that be the case at WOT?
- Is the FiTech number crank or distributor advance? I've tuned it like it's crank advance, but I can't find any information about that. However I have hard time thinking that the car would even idle at 30 degrees engine advance, so most likely the handheld shows total engine advance?
- How much the 45kPa and 95kPa setting should differ and to which direction?
The settings that I can change are like this (copied from FiTech manual):
Idle Advance = The spark advance desired at idle. (My current setting: 15)
1100 45kPa = Spark advance used just after throttle opens from idle. This value shouldn’t be much more than the Idle Advance, for this reason. (My current setting: 19)
3000 45kPa Cruise = Spark Advance used in a light cruise at 3000 RPM and throttle barely open. (My current setting: 24)
6000 45kPa = Spark Advance used in a high free-rev condition, perhaps also seen when autocrossing and just tipping-in in a low gear at high RPM. (My current setting: 29)
WOT 1100 95kPa = Spark Advance at low RPM and “full load” – perhaps the throttle is as low as 20% to see this much load. Spark is based on MAP, and MAP (and thus “load”) can get pretty high even with low throttle openings at low RPMs. (All of these are exactly same as 45kPa ones)
WOT 3000 95kPa = Spark Advance at high loads and 3000 RPM. This could easily be deemed “total” timing when comparing to a distributor, but due to the flexibility of a 3×3 matrix, this doesn’t limit you as such.
WOT 6000 95kPa = Spark Advance at high loads and 6000 RPM. At high RPM, some engines require more or less spark advance than at 3000 RPM. This allows you to set the timing there.
