Cylinder Head Reconditioning and Modification

The cylinder head will always be the key component of a performance enhancement package on any normally aspirated engine. The cylinder head has always been a reliable source of power that all successful race teams and manufacturers have utilised to stay in front of the competition, now thanks to advancements in the industry; this technology is available to the man in the street at a competitive price and can be tailored to suit any specific need. Be it that you are looking for out and out horsepower or merely for improved fuel consumption and reliability, G&C have a cylinder head solution for all your Petrol or Diesel vehicles.

Herewith procedures in cylinder head reconditioning:

 Inspection and stripping  

G&C are used extensively in the Motorsport arena for its excellence in cylinder head work. We also do some cylinder head and camshaft work for the Opel Streetracing Club members of Cape Town .This is a typical example of how we receive a head. Very rich fueling causes such carbon build-up and in some cases lack of coolant in the cooling system also causes deterioration as the water channels of the cylinder head.

No job is too difficult for G&C and we have yet to turn someone away due to cracked heads, drop seats or guides or even bent valves which have caused combustion chamber damage.





  Pressure testing  

When we receive a cylinder head, first of all a pressure test will be done. This is of vital importance as a defective head will not work well no matter how well it is ported, polished, gas flowed or cc’ ed.   We strip the head completely before we pressure test.  Each cylinder is sealed and pressure tested for any types of cracks, leaks or corrosion.   

All ports, water channels and oil channels are also tested in the same way as well. 





  Cylinder head cleaning  

Once we have determined whether the head is good, we then acid-dip the entire cylinder head to ensure that all carbon, rust and sludge is removed from the cylinder head.The head is then sand-blasted and inspected further for any hairline cracks or imperfections.  If needed, we then repair any imperfections by the use of high impact alloy welding and then work down the repaired area to its original specifications.  

It is essential that the modifications are carried out on a head that is as close to factory spec as possible.  





 Porting and polishing  

Porting is done best on a stock cylinder head as heads that have been worked out elsewhere might not yield the desired results as that of one where work has been carried out on a standard head.  Bigger isn’t always better and with our extensive experience in cylinder porting, we can increase airspeed by up to 95%CFM (for those who do not understand this type of terminology, a standard head flows +_ 80% efficient on the flow bench, so an increase in flow of up to 95% from that could be realised – we hope that this clarifies the process for those who are not in the know.)  This is what a head looks like after it has been ported.






Once the head has been ported and polished, we then accurately measure the flow of the head from the entrance of the intake (or carburetor), through the port to the combustion chamber.  This is done using a computerized flow bench which measures air speed in CFM’s to determine exactly how much more efficient a cylinder head and intake is flowing.  

The head is then further polished and fine tuned to attain the best possible flow rate on the flow bench. An increase in air speed means that more air enters the cylinder resulting in higher cylinder pressure and thus, more power.




 Valve seating  

If we are happy with the performance of the cylinder head, we then proceed to the Serdi valve angle cutting machine.  Here we are able to accurately match the valve seat area after the valve guides are fitted. Various angles and seat thickness are available to optimize your valve seating for a better combustion chamber seal. Another flow bench test is then done to furthermore improve breathing.  

With Serdi technology we are able to match valve angle to seat angle with the utmost precision.  This class-leading technology is at your fingertips during different stages of your cylinder head modification.