I am just wondering if I use the stock fuel curve and lean it out till it just starts to show knock then add the fuel to eliminate it would that get me closer to an optimum curve?? (with no changes to timing and during warm weather) BTW,I know a wideband is the best tool .

 

Bad idea.

 

it wouldnt really be much different than modifing the timing curve , I didnt mean set the entire fuel curve to 0 and start from there, but instead to gradually lower the fuel curve .

 

I'd be real careful experimenting with fuel delivery. Using spark knock as a gauge does not seem like a safe idea to me. You don't want to end up with boat anchor instead of a rotating assembly.

 

I think you are assuming its going to detonate just on the lean side of the A/F ratio that produces peak torque/HP. I don't think that's a correct assumption. I've reviewed scans showing very lean conditions (if you believe the stock O2 sensors) and not showing any knock retard.

 

I am not planning on using the O2's for any comparasin, and will be using knock count. I have very minor spark knock counts anyway (approx 500-600 total from 1st-3rd) after adjusting the timing curve. Besides Shoebox its gettin a stroker next year and the mustangs are much faster

 

I am pretty confused. What would be the goal? It sounds like you are trying to maximize economy? if you are looking to maximize hp, that is not the way to do it. Most NA small blocks make max hp in the 13:1 AF range, far richer than you would end up with.

Rich

 

At WOT fuel economy is useless, as I understand these things run rich at WOT .I want to try and get it as lean as possible then build the fuel curve at the track under real world/multiple WOT conditions.

 

What do you do if the point that results in detonation is around 14.0:1-14.5:1? You'll be a ways from the optimum point, guaranteed. Why not just start out at 13.0:1 and move it +/- 0.5. When you get the peak power/torque value, then start tweeking the timing to see if you can increase the advance and pick up a little more HP/torque, without reaching the point of detonation. Then double back and play with the fuel a little more, in very small steps.

In the end, it seem like you've already made up your mind how you're going to do it, so its all sort of pointless to even comment I guess.

 

Seriously, buy an LM-1. It'll save you a lot of money in the long run. Your pistons will thank you.

 

Yeah, this is the method to use. There is a misconception that more advance is alwys better if there is no detonation. This is not true. Ditto for the misconception that lean = more hp. There is an optimal AF ratio and an optimal timing setting for each combo, but in general NA small block Chevy's will need ~35 degrees max advance, give or take a couple of degrees. And as posted above, ~13:1 is a good place to start with the AF ratio.

IF you are running low octane fuel, you may need to retard the spark and/or make it richer (compared to the optimum) to avoid detonation. Maybe that is where you are coming from?

Rich