If you are just using the stock cam, I wouldn't bother with trying to change the cam timing, I don't think you will be able to gain much, and whatever you do gain on the top end, you will lose low end (or vice versa).

There's other cheap improvements you can make, if you haven't already, like the airbox mod, or an electric fan. Lots of other stuff.

If you can save a little $$ up, I would get a Unitek cam, and not bother with an adjustable timing gear.

But just because no one has mentioned it, if you know how much you want to change your timing, I think you can have someone make up an offset alignment key for your stock cam gear. I forget how the gear aligns to the cam...

Hope this helps!

Greg Wong

Gabe,

An adjustable cam gear is a great tuning tool. Adjusting the cam advanced/retarded more than ~ 4 degrees will make the car run very poorly. The Volvo B21 motor loses about 25-30 lbs compression when the cam pulley is retarded one notch on the timing belt. To increase the low end torque, advance the cam. To increase the top end, retard the cam. Note that this is the opposite of what someone else told you. However, that is the way it is. Pick up a performance enhancement book for just about any make of automobile and start pouring over it. Reciprocating internal combustion engines behave the same regardless of make. It's physics, pure, and not so simple.

With a VX3 cam in a B21FT (just an example), you'd probably want about 2-3 degrees of advance to the cam timing to bring back some low end power. If your timing belt is off a tooth in either direction, it's about 9 degrees, which is enough to cause problems with driveability.

I think that the standatd pulleys would not allow a fine enough adjustment. Get it wrong and your valves could end up doing a skinhead moonstomp all over the crown of your pistons (many Volvo engines are non interference but you'd be barking to risk it). How about getting a mild cam thats profiled for a bit more bottom end grunt and a set of vernier pulleys? Should be easy enough to fit and shouldn't cost too much. Alternatively you could try a new chip for your ECU which won't give massive gains but you'll feel it right accross the rev range(including sharper throttle response) whereas cams tend to just move power about rather than give a NET improvement.

I've had the same thought when reading the IPD description. I could use a little more torque driving my automatic on san francisco hills. However, by my calculations, each tooth equates to an advance or retard of about 9.5 degrees (38 teeth, 360 degrees) which sounds to me like too much to get the desired effect. Someone else would have to give the detailed description of why that's too much, but I'm figuring the adjustment on the IPD gear stops at 6 degrees for a reason.

Sounds like it would work.........

sorry i cannot give you a real expert answer, but to retard the timing slightly will up the torque, which is more in the "take off" rpm range... to advance it would up the high end power, which you wouldnt see for a little bit down the road... the adjustable gear is for you to experiment with i should think, to see if you like more horses high end, or more tractor-pull low end, and do this easily, whereas removing all the things and advancing the chain could get to be a little mean, plus for races or the like, you could change it for the day, than go back to your most fuel efficent setting back at home...