Cylinder Head Refacing / Re-surfacing

Call us for expert advice and a quotation for your engine machining requirements.

At H T Howard & Co we use our dedicated BERCO SC361 resurfacing machine to reface all types of cylinder heads.

Generally speaking, cylinder heads require refacing or “skimming” following some sort of engine failure which results in the cylinder head becoming overheated. Any distortion caused by these stresses will need to be removed to ensure the new head gasket has a perfect surface on which to seal.

There are many types of cylinder head utilising various designs and using different materials which can be hard, soft or even a mixture of the two.

Many modern engines utilise MLS (multi-layer steel) or shim type head gaskets and these require the mating surfaces of both head and block to have a very fine surface finish. The machinery and tooling that we use at H T Howard is capable of meeting these tolerances.

Machining Cylinder Heads

Materials commonly used in the manufacture of petrol cylinder heads include aluminium, cast iron and cast steel.  All of these can also be found in diesel applications with the addition of hardened pre-combustion chamber inserts which creates the added problem of machining “mixed metals” within a single job.

The machining of heads made from a single material is carried out using a single point tool equipped with a button type insert. The type of inset varies depending on the material to be machined.

Machining cylinder heads containing a mix of materlials is done using the segmented grinding wheel and special segmented grinding stones.

Aluminium Heads

For machining aluminium cylinder heads a single sided, PCD (Poly Crystaline Diamond) button insert is used.

Cast Iron and Steel Heads

For machining iron and steel cylinder heads a double sided, CBN (Cubic Boron Nitride) button insert is used.

Diesel Heads with Hardened Pre-Combustion Chamber Inserts.

When machining heads with hardened pre-combustion chamber inserts the grinding option is used. The grinding wheel attachment for the BERCO SC361 LINK is of the segmented type where small grind stones are mounted around the circumference of a large grinding head. The type of stone used can be varied depending on the material to be machined.

Grinding Wheel showing Segmented Stones

Mounting Cylinder Heads for Machining

Cylinder Head designs include flat head (side valve engines), over-head valve, cam in head and over-head cam, as well as various multi valve arrangements for some of these variants.

Each of these types can present their own machining challenges with designers choosing differing arrangements for valves and camshafts which result in cylinder heads which vary from the perfectly regular in shape to many which are totally irregular and incorporate surfaces which are angled in relation to each other.

Setting up for regular shaped cylinder heads presents no real problems with the jobs usually being clamped using traditional “T” bolts and clamped utilising the slotted parallels mounted on the machine bed.

Irregular shaped castings require more innovative ways of mounting them so that they can be machined. At H T Howard we have a range of jigs and clamps including our very versatile rollover fixture to enable us to machine just about any cylinder head configuration. The rollover fixture is fully adjustable both laterally and longitudinally and permits full adjustment to achieve the perfect set up for any irregular cylinder head. This means that we can always remove just the minimum amount of material required to correct any distortion or damage.

Using the rollover fixture, it is also possible to machine inlet and exhaust manifolds where required.

Call us for expert advice and a quotation for your engine machining requirements.