Burr sizes and shapes for head porting.

[tminer]

My stock heads have been pocket ported but I want to go ahead and port the runners and do some blending and unshroud the valves, etc.

I am looking at 6" long shanks but are they harder to control using a small pneumatic die grinder?

Also, what would be the most useful shapes (cylinder, cone, flame, ball, etc) and sizes (1/4,3/8,1/2, etc)?

I'm sure that I'd figure it out once in there, but unless I buy every size and shape, I'm probably not going to have one that I need!

tyvm,
Tom

ps For the worry warts: I don't know what I'm doing but I have the Power Source book and SA's head porting video and printed instructions.

 

[2FAST4U]

I bought a kit from here:
http://www.thomasregister.com/olc/carbtools/ . I picked the sizes and bits for the porting that I was wanting to do. I ended getting this kit:
Product #: Burr Kits
Product Name: 6- Piece Carbide Burr Kit
This product has options. See product details below.
Description: INCLUDES 1/4" SHANK TOOLS (Double Master Cut):
1) Cylindrical-No End Cut SA-5
1) Cylindrical Radius End SC-5
1) Ball Cut SD-3
1) Oval Cut SE-3
1) Tree Radius End SF-5
1) Taper-014 SL-3

The web site did list the price wrong. I believe that it was around $50. I also got a cylinder cut bit with the 6" shaft to do the runners a little.

 

[snodgrass]

The most usefull shape by far is the tree shape with the radius end, in 3/8 diameter, The next most usefull is the oval in 3/8 diameter. The 6 inch shafts are the best to get into the runners, but you can't spin them too fast. I use an electric die grinder with a reostat to slow the speed down. The electric die grinder has some mass to it, so the bit won't easily catch and jump around in the port like the air grinder. You can use the air grinder, but you just need to be careful. Some quick tips are: the throat diameter under the valve seat should measure about .200 inch smaller than the diameter of the head of the valve, a good four angle valve job that meets up to the throat is also important. The guides on these heads are really crude, and definately need to be narrowed. Don't take any metal from the port floors other than rounding the short side radius(near the valve seat). On the intake side, you can gain the most flow from raising the roof of the port(there's a ton of metal up there that can be removed, and also widen the port as much as possible near the pushrod pinch. Make the port walls as straight as possible. On the exhaust, you can basically just make it bigger all around except, don't lower the floor. On the floor, just round the short side radius like on the intake. The roof of the exhaust port is only about 1/8 inch thick, so be careful there.(don,t ask how I know). Common sense plays a huge factor. Air flowing at that speed doesn't like to turn, so use common sense to shape the port. That's why raising the port roof on any port yeilds the most gain. Again, be careful if using that air grinder, so that the bit doesn't catch and jump around and nick a valve seat. You might want to get bits with a 2 inch shaft to do the bowl areas. I'm tired of typing, so good luck, Jeff