MED ULTRA LIGHT VERNIER DUPLEX

Which cam timing setup is best? 

The choice comes down to the intended application, and also personal preference. 

The MED Ultra Light Vernier Duplex is suitable for all applications, from high-mileage road cars, to trackday and even full competition cars. With steel outer sprocket teeth, this is a good compromise between longevity and weight. 

If you are building a high-performance engine and are looking to save every gram possible, the MED X-Lite Duplex kit is some 27% lighter, with a one-piece 7075 aluminium camshaft sprocket. This is best suited to lower mileage weekend warrior road cars, or for trackday and competition usage. 

A third option is the MED Vernier Cambelt Drive, which we consider to be the ultimate setup regardless of the application. Swapping to a belt considerably reduces the weight of the rotating assembly while damping potentially damaging harmonics from the valve train. The downside? You'll need to change the belt more frequently than a chain. 

Do I keep the A+ chain tensioner?

No, this kit is designed to run without the standard chain tensioner. The standard chain tensioner is designed to be used with a simplex chain, and it has been known to fail in use with a wider duplex chain.

What should I torque the fixings to?

The six cap-head adjuster screws do not need to be excessively tight. Either tighten by hand/feel with an Allen key, or torque to 12 lb.ft with a medium strength thread lock compound. The camshaft lock nut should be torqued to 70 lb.ft, as standard, and the locktab refitted.

My sprockets are too tight on the cam/crankshaft, what do I do?

We make this kit to suit all A-Series engines, and there can be a huge variety in tolerance on the end of the crank and camshafts. The sprockets should be a snug fit, but not so tight that they need excess force to fit.

First, remove the steel keys and check for burrs. Try the sprockets in place with the keys removed, and if too tight you will need to lightly hone the centre bores to a give a snug fit.

How do I align the sprockets? 

For good reliability and longevity of the chain and sprocket teeth, it's standard practice to ensure the two sprockets are correctly aligned. 

Occasionally you may find an engine where alignment is a problem. This can be corrected with the use of shims, or preferably we would suggest to have the rear of one sprocket machined down to suit.   

Do I need to use the MED Cam Timing Cover?

This kit will fit inside the standard timing cover, but you will need to remove the internal oil shield and lightly 'adjust' one of the indentations for clearance. This applies to all duplex timing kits, so it may have already been modified. 

Otherwise the MED Cam Timing Cover fits straight over the top, reduces the chances of oil leaks and looks fantastic.

Can I just line up the dots and run the kit without adjustment? 

Potentially, although this may lead to the camshaft timing being out of tolerance. In the best case, the engine will not run very efficiently, in the worst case it could cause a catastrophic failure.

The whole idea of this kit is to allow fine adjustment of the camshaft timing for optimum performance.

Do I need to account for change stretch when setting the timing? 

Budget chains can stretch significantly, so we insist on using German-made Iwis chains, which do not give this problem. Set the cam timing as per the manufacturer's spec sheet.

What if I run out of adjustment on the slots?

It's very unlikely, unless the cam sprocket has been taken apart and reassembled incorrectly. However, if you do run out of adjustment, simply undo the screws and move around to the next slot.