TR timing belt ajustment

The Stager gauge is a simple but effective deflection gauge. One has to measure the long runs between pullys and add the 2 readings to get the number mentioned in the SB.
Do not under any conditions re-tension a belt that has over 500 miles on it.
I am currently using a Lotus electronic tuning fork (digital) to set the belts, and have moth balled the Stager gauge. Ferrari came out with their own electronic tuning fork a short time ago to replace the Stager gauge. You hold a small speaker over the belt, and flick it with your finger tip and you get a reading. Does not sound very scientific, but it is unbelieveably accurate and repeatable.
Dave

 

Dave: I use one those "clickers", commonly used for fan belts. Can this be used on the timing belt?

Why shouldn't one re-adjust the timing belt tension after 500 miles?............just curious.

 

My first reaction is no to the clicker, but on second thought, why not. The level of accuracy leaves a bit to be desired, but it is more consistant than the grab it and wiggle the belt method. You would somehow have to set a base line to see what reading is acceptable on properly set belts.
Timing belts are designed to have a small amount of stretch. Once set and run they will stretch out from the thermal expansion of the block and heads, the tension exerted from trying to turn the cams against valve springs, etc...
If you then take up that slack and ask them to go through the same cycle again, the belts will be taken past the designed stretch limit and become very weak and prone to breakage.
If I remember correctly the manual says you can reset them up to 1K miles after instalation. Someone far smarter than I wrote that, but personally I use a 1 hour run time limit. If the belt is loose within that time frame something was missed or done improperly and the engine comes back apart before a failure happens.
The 360's with their tensioner that tightens the belt when the engine warms up has a different belt design with an extra groove formed into the tooth. This groove provides a certin amount of deflection when pulled tight and spreads the tooth into the pulley groove, providing a tighter belt to pulley fit without stretching the belt out more.
Dave