Yes, unplug it, fire it up and check the timing. Be sure the engine is at operating temperature. To adjust, loosen the distributor and tweak it to the left or right as needed- usually doesn't take much. Have fun with getting it just right at 0 degrees. Seems when I go to tighten them back down the timing moves ever so slightly. Trick seems to be to leave the dizzy tight enough such that it takes a bit of effort to move it by hand. Advancing the timing beyond factory spec never did anything for me performance wise. Matter of fact, it just showed up more frequently as knock counts on my scanner. When the ECM detects knock, it retards timing. So while I had my truck that way I was probably down horse power.