Hy jockbolter50, in my Motor manual there is only one engine listed for a Corvette in 1981, as 55 SHAKER has said remove the hose at the distributor advance unit, but plug it so there is no leakage. If your truck has an automatic set the timing at between 500 and 600RPM in drive, if your truck has a standard transmission set the timing between 700 and 800 RPM in neutral. Timing should be set at 6 degrees BTDC for either transmission, hope that helps.
