Once it's determined that we are going to offer a camshaft for a particular engine, we determine the sizes of a potential cam line up based on practical knowledge and experience, performance targets and customer demand.
Next we gather all valve train component measurements such as spring seat pressure, spring pressure at various valve lifts, retainer to stem seal clearance, physical lobe clearance (if tappet bucket head), tappet bucket diameter, valve train component mass, etc. This is especially true if we are going to be offering drop in cams. If an engine has any questionable components, then these components are sent out to our laboratory for a material analysis.
Next we run various detailed calculations for maximum acceleration, velocities, valve spring stress, oil film thickness, and max RPM, with the use of proprietary piece of Cosworth software, we’re able to select the optimum grind from a substantial database.
Validation is then carried out by way of a high speed valve control check. This involves measuring the valve displacement at high engine speeds to determine if there is valve float and bounce. On successful completion of the high speed valve control check, a scuff test will be carried out. This is carried out by running the camshaft at low speed with new tappets for a reasonable length of time, ensuring the lobes don't scuff during early life. We will then run the same camshaft at maximum engine speed for an extended period of time to highlight any potential pitting of the cams, which can occur if there are any follower/lobe material compatibility problems.
Cosworth camshafts are ground on Induction hardened, cast or steel blanks. Machining and grinding of the lobes on many of our camshafts is carried out on our Junker JUCAM machine. This is hard wired into an Adcole form measuring machine so that we can grind a cam lobe nominally big then measure the form. This is then automatically corrected in the Adcole to allow for variances in geometry, temperature etc and then fed back into the Junker to produce a theoretically perfect cam form. We currently hold a form tolerance of around 0.004 to 0.006mm.
Once the machining and grinding operations are completed, the camshafts are the inspected. We then complete the camshafts by applying a high polish superfinish to reduce friction and improve the surface finish of the camshaft.