Locate the BL3102 chip. This is the clock chip for the delay chip. There is a 50pf ceramic capacitor just to the right of the BL3102. It is circled in pink in the picture above. Increasing the value of the 50pf will thicken the delay and extend the delay times. Lowering the value will give you more of a flanging effect.

If you are increasing the 50pf capacitor, I wouldn't go above 75pf. It may get too noisy. If you like switches, you can put a capacitor on a switch and run the wires in parallel with the 50pf capacitor. Putting a capacitor in parallel increases the stock capacitors value. If you wanted 75pf you would put a 25pf capacitor on the switch. 50pf + 25pf = 75pf. I put an 18pf capacitor in parallel and it sounds good with very little change in noise.

If you opt for decreasing the value of the 50pf capacitor to get more of a flanging effect I wouldn't stray too far from 50pf and probably not go below 25pf.