OK I got this! lol I did a ton of reading (not Fitech directions because some of their directions are what confuses a lot of people).
Lets start with Base Timing
Base timing, when you are using the FiTech system to control spark) is the degree of timing that the distributor should physically be at when you install it. 10 Degrees is what they suggest and here is why (for other FiTech users who may have happened upon this forum post): Base timing is only a degree of timing that the computer will use for Cranking and Firing up. It will not and should not match the timing light when you are checking the timing unless your Base Timing and your Idle Advance are the same degree of timing. Also, you need to be aware that when you physically install the distributor (after locking it out), that it be installed at 10 degrees and not back where you had it when the distributor had springs, weights and stop bushings. The reason for this is if the engine is going to use 10 degrees timing for cranking, and you installed the distributor exactly back where you had it before you locked it out (Say 12 degrees timing), it does not have the ability to spark at 10 degrees. The system can delay the spark to advance, but can not retard spark past where it physically was installed from the beginning. So you install the distributor at 10 degrees "physically" for ease of cranking and firing.... then what?
Next is Idle Advance
Another confusing point with FiTech instructions would lead you to believe that this is the amount of advance you want at Idle... Well yes.... and no :0)
Yes because this is the advance from the Base Timing you are looking for. So if Base Timing (cranking) is at 10 Degrees, as soon as the engine lights off you will most likely want to be at an advanced timing degree for Idle.
No, because this value (unlike its namesake would suggest) is not the number of degrees you want the spark to advance to at idle, but the actual timing value itself. So say the system used 10 Degrees for Base (Cranking) timing, and the engine starts. Then you want the initial timing to be 16 Degrees (like in my case). The value of Idle Advance should be 16 degrees.
OK now on to all in timing (a bit out of order-yes I know). In my particular case, it is important not to go any higher than 30 degrees of timing all in. So the value of WOT 3000 95 kPa will be my all in value of 30 degrees of timing. Also, WOT 6000 95kPa will also be 30 Degrees of timing. This will ensure I am all in at 3000 RPM and anything past it (like 6000 RPM!).
This all in value (degree in timing) also applies to 3000 45kPa (Should be 30 Degrees) and 6000 45kPa (Should also be 30 Degrees)
OK now on to the pesky (at least for me) 1100 45kPa and 1100 95kPa values. I got some conflicting information on this which made me do the o'le "2 out of 3". I called a few times (3) and have decided to go with the more popular answer the techs give me.
I was told that 1100 45kPa and 1100 95kPa should be 16 degrees in my case (same as my Idle Advance). Its not necessarily what I was thinking. I though "well, if idle advance was 16 degrees when I'm idling at 1,000 RPM and I am all in at 30 Degrees of timing at 3000 45kPa (and WOT 3000 95kPa), then maybe it should be like 22 Degrees (you know... half way between my Idle advance of 16 Degrees and my all in of 30 Degrees). Well, I was told (by the majority of techs) that it should be 16 Degrees (just like my Idle Advance value). I think what was confusing me was that it should be 16 degrees, not because of my idle advance value.... but rather coincidentally so. After speaking with the Tech's (well at least 2 of the 3 so far)... it was said that most engines will have a value of between 15 and 16 degrees at the 1100 timing events.
Now lastly.....even though we covered the Spark inputs expected from the FiTech system, I would like to touch on 2 past points (and I think Ross had gotten correct early on, but I must have just not been getting it).
Lets go back to Base timing.....
Like it was stated before, Base timing is the actual degree that the distributor should be installed at from the beginning and will be used (with no advance) for cranking and fire up. 10 degrees should allow the engine to fire up easier and quicker with less stress on the starter. As soon as it start (and I know this is recap), the computer starts using the Idle Advance Value as the degree of timing while Idling. This Idle Advance timing figure should match the balancer when you use a timing light...... If it doesn't, it means your distributor isn't really at 10 degrees of base timing! 2 options from here. Option 1-You can physically turn your distributor until your timing light shows you the timing degree matches what the handheld shows for Idle Advance. When this happens, then your distributor will truly be pointing to 10 Degrees and the FiTech system is using a spark Advance to fire the plug at your Idle Advance value (in my case 16 degrees). Option 2- is you can adjust the base timing value until your timing light matches your Idle advance value on the handheld. In this option, you are basically guessing 1 degree or 2 at a time to see where your distributor was really installed at. When you guess (and input) the correct value, them your Idle advance will be correct and the timing light will match the computer screen timing.
Lastly there is an imput Called VR Advance
The last few times I called the Tech line, they tell you not to touch it "Right now". But what is it? Well, it has to do with Chain Stretch/ Timing Belt Stretch. This value will allow you to allow for chain stretch/timing belt stretch at High RPM's (Say 4000 PRM's). So as an example, Say you have your base timing at 10 degrees (which allows your engine to Crank/Fire up easier with less stress on the starter) and your Idle Advance is 16 Degrees. Say you used the timing light at 2000 PRM's and the Timing Light matches the Idle Advance timing value on the computer screen (so your all synced up!). Now, if you rev the engine to 4,000 RPM and use the timing light to verify the FiTech computer, 2 things will happen. It will match exactly in which case your are done! Or, Due to Timing Chain Stretch/Timing Belt Stretch, you are off a few 10th's on the timing. If this is the case, you can adjust the VR advance value to account for this stretch and ensure the timing light matches what the handheld computer shows the FiTech system says(in my example it should 30 degrees total timing at 4000 RPM).
I hope this is helpful to anyone out there who comes across this. I read through may other forums and see others having the same issues with the directions being confusing. :0)
