Using custom domain on tumblr?

If I use a custom domain on tumblr do I get the link juice from tumblr? or will it consider it stand alone and not apart of tumblr

what do you mean?

You know how tumblr is PR8 and you make a blog with unique content which gives you a powerful backlink. What if you use a custom domain on your blog? will google see that the blog is apart of tumblr?

You won't get any link juice from tumblr anyway, because they only assign you a subdomain. However, the true power that tumblr gives your blog (as google sees it) stands in the amount of backlinks that you get when you are reblogged by others. Also, a tumblr blog generally gets updated several times/day (if you post or reblog others that often) and this is also something google really likes to see. So that's actually why tumblr blogs are seen so good by google...it has nothing to do with tumblr's pagerank.

Anyway, I can confirm that you can get pretty good organic traffic using both sollutions (a tumblr link or your custom domain). I have experienced both so far and I can tell you it usually takes 2 months before you see 50-100 organic hits/day, but then, if you are consistent and you grow your blog even further, it takes only one more month (3 months total) to see over 3k organic hits/day. As I said, I already tested this...