Type 4 Camshafts

This page was last updated Friday, May 18, 2007

At the heart of conventional automobile engines is the camshaft. It's the camshaft that plays a major role in determining the nature of the engine. Fortunately for us, the Type 4 has a pretty good selection of different camshaft grinds available. All Type 4 camshafts can be grouped into two different groups: solid lifter and hydraulic lifter. This article will cover the solid lifter camshafts, as I've already written an entire article dedicated to hydraulic camshafts.

The Type 4 engine in it's various applications had a variety of stock camshafts to suit the vehicle's needs. Generally there was a different camshaft for vehicles with automatic transmissions and another for manual transmissions. The earlier 411 engines had milder specs than the later 412/Bus/914 engines. My research has yet to turn up the definitive specifications for the duration and lift, but I've read a review of the Bus from the early 70's and the test drivers felt the engine was "under cammed". Now realize that "under camming" a motor will give excellent idle and off throttle response, it will also give an engine less than desirable top end power. Under camming also yields a longer life for the valve train.

As you demand more power out of your Type 4, the breathing power will need to be increased. This can include changing the camshaft for a "performance" grind. It's this author opinion that anyone looking to changing the camshaft for a "hotter" grind first look at the overall engine configuration and use. If you are using a stock 2.0 in a Bus, I would consider using a stock camshaft. The stock cam is perfectly suited for the Bus's weight, aerodynamics, and gearing. If you've added a free flowing exhaust, dual carbs (or PEFI), and a centrifugal distributor, then a cam change may be in order. The 2.0 with the above modifications in a Beetle could stand to use a "hotter" grind, as the engine isn't working as hard to push the extra weight. A general rule of thumb with cam selection in any internal combustion engine, regardless of make, as you move the duration higher, the power band is moved higher. So instead of making power from 1000-4000 rpm, a "hotter" grind would move the range to, for example, 4000-7000 rpm. Are you really going to be driving your car from 4000 to 7000 rpm? Just use common sense.

Selecting a grind

For a mild street engine, a cam grind with 270-285 degrees advertising duration and .440" valve lift (not cam lift) would be a good compromise in terms of good top end horsepower, bottom end torque, valve train life, idle characteristics, and throttle response. A cam with 270-276 duration would be ideal for a modified Bus. The extra top end given by the camshaft is not affected greatly at the low rpm range. A daily driver Bug with a Type 4 upright could stand to use a cam grind with the higher range, 276-286 degrees. The reason being that a lighter Beetle does not require as much bottom end torque to get the car moving from a dead stop, so it can move the powerband higher up. Talk to your cam supplier about your needs and listen to their recommendations. Use your head.

If you've decided to build your Type 4 as a weekend cruiser, and you want to eat Japanese wannabes and V8 American iron for dinner, then you've moved on to the "hot" category. These motors are generally larger (but not always), use wilder cam grinds, running dual Weber IDAs or PEFI, all mated to a close ratio 4-speed or Berg 5-speed. The expected life of these motors can be 20,000 to 50,000 miles before disassembly may be necessary. A "hot" engine will also require more routine maintenance, may require high octane fuel (above 92), and will cost significantly more. Think of these grinds as drag racing only grinds.

So on to the cam specifications; these cams can generally border on being racing camshafts. Duration is in the neighborhood of 290-310 advertising degrees and valve lift up to about .600". If you're familiar to Type 1 grinds, this is the same category as an Engle FK-87. The camshaft in this category probably won't make a lot of power until 3000-5000 rpm, at which point it comes in screaming. Difficult to drive on the street, but possible. These grinds will require more valve spring pressure to control the rapidly accelerating valves. Because these grinds affect the powerband, a high idle (or no idling) can be expected. Those of you who have ever driven a car with "too much" cam will know what I'm talking about.

You've decided that only a drag racing car will whet your desire for more speed. This is a car that won't be driven on the street, only on the drag strip. The life of the motor is counted in how 1/4 mile passes. In this range bottom end power is of little concern, as the power is to be made in the upper end (5000rpm and higher). Duration numbers are in the 310-330 degrees (at the cam), and the lift is matched to the potential flow of the cylinder heads.

An interesting tidbit of information: the cam grinds from Germany feature smaller lift numbers than the comparable American grinds. This means that for any given duration range, the German camshaft will have a lower lift figure. This practice moves the powerband up higher, but it doesn't broaden the power as much as the American camshaft. As a result of this practice, the camshaft require less valve spring pressure and the gentle ramps make the valvetrain live a long life.

Cam lifters

Once you've got your camshaft grind selected, you will also need to buy lifters (also referred to as cam followers or cam tappets). It is critical that you buy lifters that the cam manufacturer recommends. Mix and matching with lifters and camshafts will inevitably lead to a ruined camshaft and ruined lifters.

The reason is that you have no way of knowing the hardness of the metal of both parts. If the camshaft is softer than the lifters, the lifters will grind away at the cam lobe. If the camshaft is harder than the lifters, the lobe will wear down the lifter face. If they are the same "hardness", the camshaft and lifters will enjoy a long life.

The bottom line: make sure that you get lifters from the same place you got the camshaft and make sure that they are recommended as working together.

Cam gears

At the end of the crankshaft is a large, 5-rivet or -bolt gear that spins the camshaft at half the speed of the crankshaft. The gear is usually made out of aluminum, though some of the early Type 4s featured gears made from a magnesium alloy. These magnesium gears are pretty rare now days and generally not as strong as the aluminum gears.

The aftermarket camshafts do not come with the cam gear. They have five threaded holes that you can bolt on a gear. The gear can be purchased from the cam manufacturer or you can use a gear from a stock camshaft. Doing the latter will require you to drill out the stock rivets and then spot face the bolt area so the bolts will have a flat area to seat on.

A long time ago, tuners realized that they could free up a little amount of horsepower by making cam gears that featured "straight cut" gears. These gears featured short teeth that were perpendicular to the face of the cam gear, whereas the stock gear's teeth are at an angle to the face. It requires less force to move this type gear.

This ever small increase (usually less than one hp on an engine with 150-200hp) in power doesn't come without a price. Straight cut cam gears are quite pricey compared to the stock helical gear. They also tend to wear out faster, as there is less area for each tooth to touch. Straight cut cam gears also emit a high pitch whining noise that most find annoying, though some like the sound.

I'd only recommend using straight cut gear when you are looking to get the maximum power from a race engine or from a weekend grudge night car. The excessive cost, short life span, and whine are just not suited for 99.9% of the cars out there.

Tom Slider - Webmaster