Here is the link to the one I made for my Neon(clamped at 4.7 volts). There is probably no magic number as far as where to clamp it. You are better off adjuasting until the car runs best. With the right Pot IT is fully adjustable, Like 10 full turns. I am sure not everything applies to your car but it should work. If anyone has trouble finding parts or making one I will help you out. I have lots of extra parts.

Ted

http://www.fwdmopar.com/sites/dennis/howto.html