Cylinder Head Repair

Porting

An easy theory that’s difficult

The theory is simple: more air requires more fuel which makes more power. The theory behind it is a lot easiest than getting it done right for you. Getting that airflow requires a lot of flow bench experience otherwise your just blindly enlarging the port. My philosophy is pretty simple a given valve will only flow so much air per square inch at normal atmospheric conditions. The only thing you can do to change this is to increase the atmospheric pressure with a turbo-charge or blower hence the term (boost) We port heads to allow that valve to flow its maximum potential. If we add more area than the valve needs than it needs a larger valve. Sometimes a larger valve just won’t fit due to the valves hitting each other or hitting the cylinder wall. Some head porters just keep adding volume anyway without any additional airflow which slows airspeed and makes the port velocity lazy. I really believe in large flow numbers with minimal port volume.

Of course, this all sounds pretty simple as well. It starts to get complicated when you start shaping ports to utilize busy spots and get those dead spots busy to feed your bowl and venturi. The venturi is the area from the top cut on the valve job to half an inch into the bowl of the port. Nothing is more frustrating than having a nice venture, a nice bowl, and not enough area going over the short turn to feed it. On the flow bench, a port like this will flow well at low valve lifts. It will flow great at mid lifts. It will flow great right up until it runs out of enough area to feed the valve at this point the port goes turbulent. The flow will drop like a rock and will not recover the additional lift. This is just one of the difficulties of head porting. I don’t discourage anyone from porting their own cylinder heads. I will tell you I have a clue about what they were doing.

Flowbench

For anyone who is modifying any cylinder heads, we can flow your heads for you. Sometimes people want to verify quoted flow numbers of either a new head or someone else’s port work. Believe me, people exaggerate quite often in this business. This usually makes others exaggerate even more. We use a Superpro Probech so we’re also able to flow intakes, carburetors, throttle bodies, really just about anything. I can also advise you if there is any additional airflow left and how to get it.

Welding

Accurate Performance Machine can handle any welding need you may have. We can weld aluminum, steel, and even cast iron. We also braze and soder when applicable. If you want something fabricated with the precision we have a large Bridgeport mill and lathe. Of course, we also have tons of end mills, drill bits, fly cutters, spot facers, saws, grinders, polishers, vices, and reamers. Anything used to shape or form metal we have it. Whatever it is you need made we can do it.