Are there any negative effects of tightening the timing belt.. i know the car will feel nicer, but why is there a factory spec. tension then?

 

Overtightening it will cause increased friction and abnormal wear to the belt and pulleys.

 

How do I know how tight to make it?

Jon

 

How can you over tighten it?

The process is to loosen the nut 180 degrees, move the cam COUNTER clockwise 3 teeth, and then tighten nut..

not much room for error?

 

actually, if you have a milled head or thinner headgasket, the factory tensioner will not bring the tension of the T-belt up to spec. therefore, you must manually tension the belt yourself. when i first did this,i was unsure how tight it shoul dhave been, so i popped the valve cover off of my wifes si, and "twisted" the belt, felt what the tension should be, and ran over to my car and made it the same.

 

I've found that if you reuse a tensioner and belt the belt will not be as tight as it should. I've seen many belts that were too loose and the person lost a substantial amount of power from it. It makes lots of sense because you are losing some timing with the belt being that loose.

Anyways, a trick to tighten the belt more is to have the valve cover off along with the upper belt cover and position a pry bar or long flathead underneath the tensioner, just follow the spring down to the tensioner and go underneath it. This is after you turn the crank 3 notches though. Then put a bit of pressure, not too much and feel the tension on the belt on the intake side of the motor. You can feel the difference when you put more pressure on the tensioner. There should be a little slack in it, do not over tighten, you kinda have to play with a it a bit. Then tighten the tensioner bolt. Rotate the motor 3 complete revolutions and check the tension. After you start the car, if there is howl or whine coming from that area, the belt is too tight. Retension if necessary.

 

OEM tension on an ITR is 40ftlbs.