Weird that the 302 in my 89 runs better with timing at about 18deg.does that make any sense and does anyone else run their timing that high??

 

How much timing does the computer add on top of initial???

 

Your timing chain probably has a lot of slack, i would be looking for a replacement if it were so. Aren't you hearing any detonations?, this is way too much advance, and also, did you remove the SPOUT before setting the timing? if you didn't the computer probably tried to adjust to the stock setting of 10° BTDC, the usual advance that doesn't risk on hurting anything is 12° - 14° BTDC.

 

In the river valley here in the Gateway City's humid summers the best I've ever done with base timing is 11º BTDC. Notice I said BASE timing. If you haven't set base timing correctly, the computer won't "know" it and the timing corrections it makes will screw with performance.

Absolute critical requirements for setting base timing:

1. Engine at full operating temperature
2. SPOUT "connector" (shunt) REMOVED.
3. ECM CLEARED of fault Codes before restoring SPOUT.

NOTE: This is NOT an instruction list for setting base timing! The full procedure has been repeated too many times to count in this forum and many others.