[bobcowan]

>> As far as I understand, the pinion angle should be at +3degrees. <<

Pinion angle is a complicated subject, and easy to get wrong. The first thing is, what is pinion angle, exactly? The pinion angle is measured against the drive line, not the horizon. This is a key point. Maybe the most important points. Before setting pinion angle, you have to install the drive line and measure the power angle.

The second thing is, what are you tryng to accomplish? Under power, you want the drivce line angle and the pinion angle to be exactly the same. When they're not the same, it costs you power. Street cars do well with 1.5-2.0*, drag racers do well at about 3-3.5*. IRS cars get 0*. Again, all compared to the power angle, not the horizon.

When you let out the clutch, the tires want to spin one way, and the differential wants to spin the other way. That changes the pinion angle, and brings it closer to the power angle. It may move a lot, or just a little, depending on how the car is built and used.

Do a google search on pinion angle, and you'll get lots of info with pictures.

On the other Cobra forum, we've discussed this quite a few times, with some excellent info and pictures.