Thinking about doing a build to get more power so I am doing research. Been checking out all the companies who do headwork, see a lot of guys using four axis CNC machines.
I run cnc equipment for a living, in fact we have quite a few four and five axis machines. Depending on the part being made and the program, the machines are fairly consistent but they do vary. Surely the ports in factory cast heads vary too. If you were maching the heads from a blank, I could see the cnc making a good set of heads. Since the ports are already cast in the heads, and I am sure the castings do vary....how accurate of a port job can a cnc machine do? Looks like there is a lot of room for mistakes.
Just something that is on my mind before I spend my $

 

A cnc port is only as good as the master heads from which they were lasered, or digitized originally.
In other words if you plant corn, you get corn.
Skilled cylinder head men that virtually live behind a die grinder, 8 hrs a day, 5-6 days a week, and use a flow bench to verify what they are looking for is how many of us do it.
We have had our heads digitized long ago, and upon return to us, some areas of the port were not touched by the cnc cutter.
Is that bad, no, but the machine will only do what it is progammed to do.
A cnc will spit those heads out quickly, BUT there is still more precision work to be established once that process is completed.
Scott

 

Yep, Scott has a very good point ... Core shifting is common and in some cases quite exaggerated leaving a CNC head with room for improvement ... a competent/qualified technician can "clean it up" or recommend that you start over.

 

I would say the quality of the cnc port would also depend on the machine set up man and how well the machine is dialed in. Our programs are always close but can vary by day, machine and operator. I make tooling with tolerences of 5 microns, have witnessed programs vary by as much as .0025" (63.5 microns) on million dollar 5 axis equipment. Being off when cutting a radius multiplies the mistake, which I guess isnt bad if you didnt take enough out, that can be reworked with the machine or manually.What happens when too much is taken out in the wrong area, we make scrap. I can make a part closer to spec manually, I can make more parts within tolerence with the machine. This makes me wonder if I will get a better set of heads with a hand port? Or are the cnc heads cut close and then finished by hand?

 

The answer is both, a good cnc head with light hand finishing will produce the same day in and day out.

 

IF the head was good to start with.many guys think CNC= good heads,not true.like said before (many times),if the head that was digitized had good ports,the rest of the heads machined will be about as good (as good with some hand finishing),if the original heads were junk,the rest machined will be just as bad

 

If the head being digitized was junk and the guy knew it, you wouldn't want a hand ported head from him either. My point is:Trust. Either you can or you can trust the shop doing the heads, cnc or hand ported. Edit:meant to say "you can or CAN'T trust" ooooops , i think yall got what I was tryin to say.

 

100% true.

 

Like I said...........you plant corn, you get corn........
Scott

 

All my heads are purchased CNC ported, H-D performance heads. I assume they are decent high volume production heads. How much room for improvement was left on the table that could be found with the right hand porting?