I've got a 6AL for a 4 cylinder Mod 4 Ford 2300 engine. It has a rev limiter chip in it but does not have a chip specifying 4 cylinders. I was thinking that it needs that. If it does where can I find one? Thanks.
There is no difference as Ed said an MSD chip is nothing more than a resistor like what you can buy at Radio Shack. Before the digital boxes I made rotary dial two step boxes, the two step was nothing more than a relay to switch between resistors for a rev limiter and a low side for the brake. I built a couple different ones, one with a rotary switch with progressive resistance values to increase or decrease RPM as needed and the other with potentiometers which are variable resistors. I also got the resistance so I could set the low side below 3000 RPM which was the lowest chip MSD had at the time.
Your 6al should be set for four cyls. The chips are the same for all.
I agree you need to set it for the 4 cylinder, if I remember right one of the boxes has a few different looped wires coming off the side and you cut the one for the 4 cylinder