Hi guys, I have a 1985 Corvette with an L98 engine with a lot of modifications. I usually pay someone to do my tunes for me, but for this little incident, I would like to modify it a little myself instead of paying my tuner again for something so small.

Here's the situation. I had adjusted my valves using this method: Engine running, loosen rocker arm nut until you hear valve chatter, tighten until it stops chattering, go a 1/4 turn.

Well this method caused some backfiring during revving, I could not hear my valves accurately because of all the noise the exhaust makes.

So I did it the way that Alldata says to do it, which is tightening the nut while spinning the pushrods until they are dragging, then go 3/4 of a turn, lining up the timing marks on compression strokes and then exhaust strokes so on and so forth, I did it in the proper order essentially.

Now the car does not backfire anymore.

Previously, my AFR gauge read 12.4:1 at WOT, pretty close to where I would like it to be at 12.5:1.

With my recent adjustment, the AFR at WOT is now between 11.8:1 - 12.1:1, and I would like to lean it out just a tiny bit. I have a picture of my current settings for AFR vs WOT and AFR at WOT vs Coolant Temp.

Can someone take a look at these and tell me what I need to change these numbers to to bring the AFR to 12.5:1 please? Thank you very much and Merry Christmas!

 

It appears the best way to accomplish that easily (but not exactly) is to adjust the %change Vs. coolant in the 56,up to and including the 102 entry.
The normal way I would do it is by RPM but you have no room to come down so temp table will change the RPM table across the board.
Drop it by the percent difference and give it a try.
This is figuring that the main fueling tables run good everywhere else since they are the basis of the % adder used in the tables you have shown.
HTH,
Jp

 

AAAA, No you can go negative in the RPM table. I would leave the coolant table alone. With your values at 17.58% and 0.0, your COMMANDED AFR is 12.525. (calculated). if you plug in -3.00 for the RPMs that you need to change, it goes lean to 12.85. Try that, but be careful. You dont want to go too lean at WOT.