port job

[youngmonte71]

random ?. what is a port job on heads? if someone can explain that to me. thank you =)

[Andy's Auto]

A " Port Job" refers to the stopovers of Navy seamen during WW2.

 

Now that the bad joke is out the way, a port job refers to reshaping the combustion chamber and intake/exhaust ports to increase overall flow and efficiancy. It cam be achieved by either hand grinding or CNC machining.

[youngmonte71]

so do they like machine the intake and exhaust ports? is that what it is?

[Mike 57]

Porting used to be done by hand with a die grinder and different shaped carbide burrs to shape the port for better flow. A device called a flow bench was used to verify the gains in flow. Cast iron heads used to take days to port. Now days aluminum heads are easier to work with and the advent on CNC machines made porting very repeatable once a port was designed. That is the short answer.

[youngmonte71]

how much of a power gain is there if you port your heads?

[Mike 57]

There could be small gains by doing a port match, bowl blend, with a multi angle valve job and back cutting the valves. Porting is an "art" and you can do as much harm as good especially around the area of the short side radius. Intake ports like a rough finish and exhaust like smooth. You can dump tons of time or money if you have someone do the work on a set of stock cast iron heads and still never reach the potential of a AFR, Dart, Brodix, and other aftermarket heads.