which tabel do I modify teh advance from? Also is tehre any way to adjust the afr to around 12.5:1 with out wide band o2 sensors somewhat accurately?

 

You use the main spark advance and the extended spark advance to modify the SA. The main is the lower rpms and the extended is the higher rpms. Personally, I wouldn't play with this too much, the SA on the LT1 is pretty much at optimum already. If you are going to adjust, try only adding 1 or 2 degrees across the board, then going out and logging for about 15-30 minutes to make sure you aren't getting any knock at any rpm. It's about all the higher you can go without getting major knock, and most of the time you can't give up it by that. It just depends on your car, but don't expect any noticable gains. The AFR is possible, but it is much easier with the wideband. There's an equation in the help files, I believe.

 

Thanks man, I also have another question, I have datamaster and looking at the o2 readings at WOT they are between 900-950 in the first 2 gears but as I go into 3rd adn 4th they lower to about 870-900... is that normal?

 

The stock O2 sensor readings really aren't very good for determining the AFR, but that sounds about right. Anywhere from like 850-950 is what you will usually see at WOT, but it can be higher/lower too and still be ok. As long as it isn't reading 300mV or anything really low like that, your fine. Of course, if the mV reads 300, I think you'll know it long before you see it on the computer! A wideband is really what you need to get the correct AFR. Since the Fbodies are tuned to run rich from the factory, you can lean out the AFR and you'll probably see the mV drop 50-100 mV or so, but still, the O2s aren't very accurate. Just make sure to keep running datamaster after you tune to test and nothing really bad goes wrong. You should be fine that way.

 

well when at part throttle it bounces around all over teh place down to single digets a few times... am I right to assume that this is normal when not WOT?

 

Yes, it's normal because the closed-loop equations are constantly adjusting the air/fuel ratio, so the mV should jump all over. When you go to WOT, the enrichment program kicks in an just dumps the set amount of fuel into the air without checking the O2 sensors. That's why you see that 850-950 mV reading at WOT, rather than the jumping you see under part throttle.

 

If your BLMs are around 128 when driving now, then you shouldn't "need" a dyno to set the AFR at any given RPM.

There is a formula, listed in the help file, that will show you how to set the target AFR at WOT. Again, as long as your car is running near 14.7:1 in closed loop (close to 128 long term BLMs), then your targetted AFR should be near-dead-on.

I agree with DOOM about the spark. I could only add about 2-3* throughout the range without getting knock... on 93 octane.

 

These cars run rich stock at WOT, but if your near 128 as said then your doing allright, you wont see much power gain if your nearly stock, figure on 10-15 HP is what I've heard, and thats probably only within a 1000-2000 RPM range as for most of the gain, not something across the board making freaky power everywhere, its probably only at the high RPMs and since the power is peaked out at 5200 RPM stock your not going to see a ton of gain without mods.

Without the wideband, there is no way to accurately read a narrow band sensor, you'd be guessing, and thats playing with fire to a degree.