CAM BELT AND CAM UPGRADE Here’s how to renew the timing belt, tensioner and idlers on the C20LET and fit an XE inlet cam with a Vernier pulley.
The turbocharged 2-litre C20LET is a relatively straightforward engine with a twin cam head and a single timing belt wrapped around two idler pulleys and one tensioner. While it was originally fitted to the Cavalier and Calibra Turbo, it’s now a common sight under the bonnet of many a modified Nova, Corsa, Tigra and Astra thanks to its factory 204 bhp at 5600 rpm and the availability of numerous tuning options.
Whether you’re new or well-attuned to the C20LET, it’s worth knowing what’s involved in maintaining this popular motor, so we’ve teamed up with M J Motors to show how to renew the timing belt, idlers, tensioner and
PERFORMANCE VAUXHALL water pump. This should be done every 40,000 miles and typically takes half a day to complete, depending on how much space you have in the engine bay. For the sake of photos and to avoid lots of shots of fingers and thumbs, we removed the engine from a Calibra Turbo to make it easier to outline the work involved.
Typical problems associated with renewing the timing belt on the C20LET start with the timing belt cover. This plastic cover is secured with three 10mm bolts, which sit in 1mm studs in the front of the engine. These studs can shear off and the solution when this happens is drill them out, which can be tricky. Leaving the timing belt cover off is the easy way around this, but you don’t want road dirt and debris wrapped around your timing belt.
When changing the timing belt, it’s worthwhile renewing the water pump if you’re unsure how old it is. This is sometimes stuck in the engine block and will need some persuasion with a long screwdriver to help release it.
We’ve not only shown how to renew the timing belt, idlers, tensioner and water pump, but we’ve also provided step-by-step instructions on one of the popular C20LET mods – namely fitting the XE inlet cam with a Vernier pulley. The XE inlet cam has a higher lift over the standard C20LET inlet cam, but has to be accurately timed using a Vernier pulley. A standard pulley will fit, but the timing will be wrong.
Many people chose to fit a second- Spanners/sockets: Metric - 10, 13, 15, 17, 25 mm Allen keys - 5, 6 mm Torx - E10, E20 Torque wrench - 20-50 Nm Various screwdrivers and a scraper Multi-purpose grease hand XE inlet cam, but this can sometimes defeat the point of the modification, unless you’re sure it’s in good condition. A visual inspection of a second-hand cam will hopefully spot any cracks or excessive wear, but there has to be a significant saving over brand new parts for a second-hand part to make sense. SBD Motorsport for instance, sell a brand-new XE inlet cam made by Kent Cams for £288 (including VAT) and a pair of Kent Vernier pulleys for £229.
The following 20 steps show what’s involved in renewing the timing belt, idlers, tensioner and water pump on the C20LET and swapping the standard inlet cam and pulley for an XE cam and Vernier pulley.