GX345 ?

[RG1]

When I turn the dial, I can feel the clicks so I think that means The cam is turning since it does change the cutting height, but wit the dial set all the way on 4 it still cuts too short. Am I right in thinking the dial and the blades need to be adjusted to be in sync ?

The dial, linkage to the deck all need to be set to correspond with each other. You need to be careful when doing it though. You don't want to get the deck out of level from side to side, or out of pitch from front to back.

As a side note:

Pitch on most JD's works best when set at 3/8" front to rear on the blades themselves (not the deck shell). The manual usually recommends 1/8" to 1/2' depending on which deck and machine, but I have played with around 20 JD's now, and they do their best cutting at 3/8" when checked over deal flat and smooth concrete. Even a little dip or hump can throw the reading way off. I use a 6' level to check for a smooth flat spot. I use the JD deck leveling gauge sold at most JD dealers for around $8-10.