It's been some time since my last post. It's not that anything hasn't been happening. Simply that other projects have take priority over my car projects--mostly home improvement. The corrado however is the largest presence in my garage and bright yellow paint is a daunting reminder that it is a pending project impatiently waiting in the wings for some attention.
In an effort to button up the engine compartment, I decided to overcome my procrastination and install the cam that's been sitting in its original box for several years. My top end was totally stock save for replacement of the lifters a few years back. Despite replacement, it is always a good idea to replace lifters when replacing a cam.
I purchased a mild 260 cam from Autotech. The more aggressive cam profiles would have mandated higher performance springs and some other items. At this point, I think I would have rather spent the money on a ported and polished head. But budget is limited. I had once considered the Schrick cam which are considered the premier performance cams for my car. However the expense was prohibitive approaching Porsche performance parts prices. So the choices narrowed to the more affordable Techtonics or Autotech. Both had a good reputation for quality and were more in my price range. I did not conduct any objective comparison of the two candidates in my selection process. The Autotech simply went on sale--therefore the decision was made by the wallet.
I also purchased their adjustable cam sprocket
which many purchase to manipulate the torque range. This changes engine characteristics by allowing one to move the torque range up or down the rpm range. However, in my case, an adjustable cam sprocket allows a certain measure of error correction without having to reposition the belt which is a labor intensive effort. Adjusting the sprocket allows me to make quick adjustment to cover my error should I install the timing belt improperly. The Autotech Cam sprocket is also much more visually appealing than the OEM sprocket on the left.
Other items that were necessary included a new valve cover gasket, thread locker, and a new set of hydraulic lifters. I also purchased a new cam seal. Assembly lube comes with the cam.
The other essential tool in this project is the Bentley Manual. Removal and installation of the cam caps is a precise procedure and requires a sequence of bolts to be loosened/tightened in a specific order. The Bentley manual details which bolts and in which order. Final torque specs are also very important.
Once the cam is removed, the hydraulic lifters can be replaced. They simply lift out of their bores. A magnet is helpful in this step. Note that new hydraulic lifters are packaged in oil. It is also important to note that the package must be kept right side up to prevent the oil from draining from the lifters and going dry in the package. See the warning label on the lifter package to the right? Keep the bottom of the lifters facing up when in storage until you are ready to install them.
Upon installation, one simply drops the lifter --open side down-- into the valve bores. The oil will then begin to drain out allowing the lifter to compress on top of the valve stem. It is important to allow this oil to drain out once installed so wait 45 minutes before starting up the engine. Most of us can't reassemble a motor that quickly so that message is usually lost on a shade tree mechanic like myself. But it is noteworthy because starting the motor before it is properly drained prevents the lifter from proper compression which may damage the valve or extend it too far into the compression chamber.
Once the assembly is out of the car, I used an air compressor and an impact wrench to remove the old sprocket from the old cam. Even though I am using a new cam and sprocket, I still need to reuse the original woodruff key which is still installed on the old cam shaft. Do not damage or loose this tiny part! It is pressed into a small chamfer in the camshaft and interfaces with the sprocket to prevent it from rotating on the shaft.
Use the detailed procedure in the Bentley to reassemble. I coat all of the contact surfaces with a thin layer of assembly lube. Each cap belongs in a specific place and it is oriented in a specific direction. Take note and keep them organized when you remove them. This will help you place them back in the position from which they originally came. Then I torque everything back to spec in the sequence outlined in the Bentley manual. Doing otherwise and you risk twisting the cam and damaging the bearing surfaces rendering your parts and the head unusable. That's an expensive mistake!
Once installed, the CAM sprocket is a visually impressive addition to the engine bay. But the timing belt cover will conceal this modification and keep it clean under real world driving conditions.
Next up is belt replacement and more interesting salvage yard discoveries.
Comments
Thanks!