Possible to change a/f target?

My understanding is that the LT1 OBd1 PCM targets 14.7 to 1 for A/f ratio. Is it possible to adjust the target to say, 13 to 1?

Tell us what you're trying to do.

It can be done and in a few different ways, but how you accomplish it is really dependant on what you are trying to do.

I have minor cam surge at lower loaded RPM's. My tuner states that the motor want more gas in these areas but the PCM wont provide it with affecting everything across the board with tuning tweaks.

I have a closed loop tune that eliminates all cam surge but I don't know what possible negatives might arise if any. I would like to run a closed loop tune that will eliminate the cam surge. It was suggested to me that if the a/f ratio could be moved to 13 to 1 then that might do the trick.

I am not an expert here, just trying to get educated.

Change o2 switch mv vs airflow mode, adjust closed airflow modes to bracket in the problem area. Try more timing in problem area, it'll make the motor tolerate leaner mixtures better.

The other thing you can do is if your blms are really close to 128 all over, you can introduce error into the maf tables at the problem area, and put the blm up against the limit which you would move up from the stock 108.

There is nothing wrong with an open loop tune assuming everything is correct and the cruise a/f ratios are reasonable. mileage will probably suffer with full time open loop.