I'm new here so forgive me if I don't know all of the terminology. I have a small Valencia tree (trunk is about 2" and tree is about 4' tall) that I would like to graft over to entirely to another strain of Valencia.

What is the best method to do this and when? How many grafts do I do? Do I get a few going and then remove the old cultivar or do I top the tree entirely?

For topworking the bark graft method works best. Here is a link to a tutorial by Joe Real--http://citrus.forumup.org/viewtopic.php?t=1762&mforum=citrus

If you are new to grafting I would suggest you try the t bud
method and do 2 on each scaffold branch then force them. Then I would try the bark method on some of the new growth.
I think skeet has a tutorial on t budding somewhere here.

David,
Then do I cut out all of the old cultivar growth once the grafts have taken and are growing?

If you are gonna t bud low to the ground you do what lazz did here. But if you do a scaffold branch you can continue to add new varieties to the other scaffold branches.
Here us a great pictorial that lazz presents( thought it was skeet).

If you are gonna t bud low to the ground you do what lazz did here. But if you do a scaffold branch you can continue to add new varieties to the other scaffold branches.
Here us a great pictorial that lazz presents( thought it was skeet).
link
... Forgot to mention that t bud and bark grafting( the link that skeet has up there) can only be done when the bark is slipping.

David's suggestion of T-budding will keep the existing structure until you are certain you have a good graft --then you can cut it off. With bark grafting, you will cut off first--the graft may fail.

The other point about bark slipping--it usually slips when the tree is actively growing.

Skeet,
So I should try next time I see the tree putting out new shoots?

Does citrus have a growing season or is it normal for it to grow sporadically? I planted several measly 5 gallon orange trees, about eight months ago and none of them have shown any real growth except this one Valencia. It's had three growth spurts and is already the size of a large 15 gallon tree.

Jeff

In my experience here in Texas we have alot of warm weather and flushes are practically every 2 months. But to answer your question , the spring flush is for me the longest and strongest so yes next flush you see would be best. You can try some practise cuts away from where you plan on grafting and see if you can lift the cambium layer away from the bark easily, if so graft away. Keep into consideration that temps would be best above 60 low and high not to exceed 90.
Skeet may also have some more tips and tricks.

Considering that the tree already has a sizable trunk, should my goal be to graft several buds at the top of the trunk and have them become scaffold branches or should I place my bud at the base of the trunk and let it become the new trunk?

Jeff

That is a matter of choice. For me I would graft onto the scaffold branches with differtnt varieties--like I have with my lemon tree that now has over 15 varieties on it, but still produces more lemons than I can use.

There are grafting techniques that you can use when the bark is not slipping--chip grafting, cleft, and tongue grafting.

If I graft to the top of the trunk, will the old cultivar keep trying to reemerge below the grafts? I'm guessing it would the same way a bud occasionally grow out of the rootstock.

Jeff

Does your tree have any scoffold limbs , or is it just one stick ?
Could you post a pic?

I got my budwood from CCPP today. Now what? I have three varieties and I want to graft three of my trees over to these cultivars. I have the buds, all of the supplies, I've looked at a bunch of grafting tutorials and I think I can do it but I'm not sure when to do it or where on the trees.

I'll post some pictures of the three trees and maybe you guys can tell me where and how to graft.

Jeff

The first tree is a Fisher navel that I want to graft over to Newhall Navel and I'm thinking I should be t-budding at the top of the trunk, just below the scaffold limbs?