timing belt question

[leone30]

I just replaced a timing belt. I need opinion regarding the procedure. I did it not the first time on my car. As usual, I removed the spark plugs, then peeled off the old T-belt, replaced roller-idler with a new one, fitted a new timing belt, released the idler and run about 5 full rotations of the crank shaft with 22mm wrench in order to let the new timing belt seat properly over crank shaft pulley, camshaft pulley and the roller-idler. Of course, I checked all the notches for timing. I did not lock the idler yet. Then I installed the spark plugs and run few rotation of the crank shaft. And what I noticed.
When a piston in one of the cylinders reaches TDC there is significant force required to turn the crank shaft and at this time incoming branch (view from the top of the motor) of the TB getting loosened and the idler moves about 1/8 of an inch toward a generator because the tension spring pushes the idler and this keeps tension of the belt constant. This condition I call “preloading”. After TDC is passed almost no force needed to rotate the crank. And tension difference between incoming and out-coming branches of the TB equalizes and the roller moves back about 1/8 of an inch. So I always lock the idle while keeping the TB “preloaded” with the wrench on the crank shaft. I think, this makes TB tension constant during spinning. Am I right?
Thank you.

[Sagaris]

Are you asking whether the tensioner is constantly moving and adjusting while the engine is running?

If so, no, the torque generated at the crankshaft takes up slack on the right side of the belt and the tensioner takes up the slack on the left.

If that was not the question then I am sorry, it is early, and I tried :D

[MTechnikII]

One very important point you have to remember in TB changing is that the TB is stretched on the other side of the tensioner, the slack is on the tensioner side which the roller take cars of it, the way I do it ( figured it out after 4 TB changes on my cars) is
place the timing belt around the crank gear and hold the belt tightly close to the gear and stretch the belt all the way up and around the camshaft gear while holding it close and tightly to the crank gear ,
push the tensiner in wards to take the slack of the belt off and tighten the bolt for the tensioner, if you don't hold the belt tightly to the crank gear, as you tighten the tensionar the gears will move a tooth or two , it hapened to me once and the engine sounded like a diesel engine, I think you have room for a tooth or two but not much before the valves are bent.
I always turn the engine with the old belt on to the timing marks, on crank and cam shafts and slip the belt out and slip tyhe new one on, and tighten the tensioner,
if you have the markings aligned , and the plugs installed its normal to have some compression resistance while turning the engine, but I don't think its a good idea to turn it with the tensioner loose.
Henry

[Kershaw]

once you installed the spark plugs you are suddenly building compression. obviously its hard to turn... once compression is released then it'll be easier to turn.

as long as its always easy when the plugs are out, and the timing marks are always lining up. you're good.