I have a few sites that rank #1 on certain keywords google.ca, however on google.com it may be on the 3rd or 4th page... I assumed this is because I am hosted in Canada with a Canadian IP address... Now I want to move to a dedicated box in the US.. will I lose my rankings in google.ca if i have a US ip address?
yes you may experience some harsh drops in rankings but they may return to normal after some time. ...or may be not but there will be some shuffling definitely.
That is not necessarily true seoz. It comes down to that you just do not know, I for one have experience with the other way around. My sites were targeting Canadian visitors, but were hosted on US IP. I changed all sites to be hosted on CA IP in the hopes the rankings would go up (all were top 5), it has been 8 months and the rankings never changed a single spot. Only thing that changed for me was that my sites started rankinging for searches from "pages from Canada" in Google.ca, but other than that no changes whatsoever in google.com or google.ca Of course for other people the result can be different, but since rankings consists of so many factors it is impossible to tell what is making the difference. Is it the link from an authority website that you acquired 4 months ago and is finally aging, is it the links from a variety of sources that help your ranking after 1-3 months, is it that google changed the algorithm, is it because you changed IP, is it because you added good content, is it because you established yourself in the circle of authority domains after many months or ... Basically you can never know what exactly caused the change in rankings as the effect google gives it takes anywhere from a couple of days to many, many months. My advice is that you simply host the sites in the country that you are targeting, that way you can at least be sure that you did your part so you can focus on other things in your control, such as adding content, acquiring quality backlinks.
You will experience some drops on google.ca but you may increase your position on google.com as your moving to a us server
moving to a us server will increase your serp in google.com and if you want to keep your ranking in google.ca, you mat try getting backlinks from sites hosted with canadian ip address.