Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Cylinder Head Porting - INFO please.
View Single Post
  #3 (permalink)  
Old 04-22-2011, 11:53 AM
cobalt327's Avatar
cobalt327 cobalt327 is offline
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by vk-v8
Hello,

I am about to Port my Cylinder heads on my 304 V8, and the intake manifold.
I have a Air compressor and a Air die grinder.

Now all I need it a the Porting Kit. What is everything that I need?

What carbide burs do I need?
What Sanding bits do I need?
What polishing bits do I need?

Where can I buy a kit from? I am in Australia BTW..
Do I need the Carbide bur or can I just use the sand paper?
Do I need to polish it after?

Thanks!
Welcome aboard.

My understanding of the 304 leads me to believe the head has an almost ideal cross sectional area for the valves it comes with. What this means in terms of porting the heads, is you need not remove any large amount of material to get good results. This also means that you likely do not need any carbide cutters, period. Instead, I would plan on using sanding rolls (both tapered and straight) and you need not go any finer than 80 grit- this means you do not need to polish the ports, especially not on the intake side. If you wanted, you could go to a finer finish on the exhaust side, but IMO it's really not necessary.

I would concentrate on smoothing and removing any casting "flash" or irregularities, and on the valve seat to bowl transition- there is almost always a pronounced lip created by the machining of the seat. Avoid hitting the seats w/the tooling you use! If you do any work to the combustion chamber, use old valves to protect the seats. Then streamline the shape around the valve guide, but do not shorten it. Be sure the intake-to-head port openings are in alignment, but do not "bell mouth" the ports to make this happen, as is often the case when "gasket matching" is done. That only serves to disrupt the flow as it hits the bulge- which slows the flow velocity- and stacks up the flow behind it, creating less rather than more flow. There are tutorials here and elsewhere (use the search function) that shows how to properly mate the two openings w/o creating any unnecessary bulge.

If this is not news to you, disregard it- there's a large variation in experience among the membership here, and there's no way to know offhand what you come into this with, experience-wise.

Good luck.
Reply With Quote