Acceptable amount of slop when setting the timing?

[jason]

What is an acceptable amount of slop when setting the timing? I cannot get the timing mark on the flywheel to line up perfect when the camshaft and IP are locked; the timing mark is always about an 1/8 of an inch towards the passenger compartment, is this normal? I have turned the engine over by hand quite a few times and have never felt the valves and pistons hitting; I am worried that once I fire it up and bring it to 2 or 3 thousand rpm I will damage something. Any advice is appreciated.

Thanks,
Jason

[jason]

I have also loosened the camshaft sprocket so it will rotate freely, but I still cannot get it right; do I possibly just need to make a crankshaft holder?

[VanagonExpress]

You mean when you go to tighten the tensioner, the crank moves?

Your cam sproket is loose?

[Vincent Waldon]

I have also loosened the camshaft sprocket so it will rotate freely, but I still cannot get it right; do I possibly just need to make a crankshaft holder?

Nope... but based on your engine's geometry you may need to wiggle the pin in the injector pump a bit. At the beginning it doesn't matter if the injector sprocket is off a bit... you'll get it perfect with the dial gauge later. Worst case... use the pin in the injector sprocket to confirm that the belt is on all the right teeth and then pull it so you can rotate the engine to exactly TDC.

The most important thing is that the crankshaft is at exactly TDC *AND* the cam is exactly locked (flat bar stock in groove, equal number of feeler gauges at both sides as needed to make it tight).

Then: tighten the cam sprocket (don't depend on the camshaft lock to hold it).

Then: pull all the locks and use the dial gauge to set the pump timing exactly

Then: rotate the engine a couple of times to confirm that nothing is binding

Then: fire her up

[libbybapa]

To answer the original poster: crank, cam and pump timing should be exact. If it is set correctly it will be. If the belt tension is loaded the correct way then the crankshaft will not move at all when the tensioner is tightened.

I'll quote myself here:

FWIW, the timing belt should be taut between the crank, injection pump and cam with all of the slack in the tensioner area and the crank and cam at TDC prior to tensioning (as it would be while running). When they are properly positioned with all of the slack in the tensioner area, then tensioning the belt doesn't move the crank a wit. Also, the "tensioner" doesn't really apply tension to the belt, but just takes up all slack. The actual belt tension is maintained by the crank driving the system and the resistance of the pump and cam. Over-tightening the tensioner will trash the pump shaft bushings and intermediate shaft bearings.

Andrew

Like slack in the timing belt, when ever I put a timing belt on they are always so tight that I have to pop the cam gear off put the belt on the gear and then slide it on the tapered cone, torque, then set the tensioner, which with the belt already taught always moves the flywheel some.

There is an inherent contradiction there. Tightening the tensioner does not put any rotational force on the timing belt in order to rotate the entire engine (crank/pump/cam). If the crank moves when the tensioner is tensioned, then there was some slack between crank/pump/cam and the act of tensioning the tensioner splayed the crank clockwise and the cam counterclockwise.

I hope that after you tension a belt that way, you do a complete clockwise rotation of the crank back to TDC (without any CCW rotation if you pass TDC) and verify that the cam is not retarded...

I like to leave the crank a couple of degrees BTDC until the belt is on making sure it is meshed correcly with the pump. Cam gets lightly tightened so the sproket can still turn and then the sprocket is turned CCW on the cam slightly to make sure there is no extra room for movement between cam and pump. Then crank goes the couple degrees to TDC, the tensioner gets tensioned, cam gets torqued. I still doublecheck cam after a complete rotation of crank. Works for me. Like you said experiences can vary.

Andrew

[hagar]

What is an acceptable amount of slop when setting the timing? ------ at hagar's there is NO such thing.

Here we synchronize Crank , Cam and Injection pump ----exactly ---no SLOP not never..

Belt and cam sprocket has NOTHING to do with it.-------here we make sure that both valves on # 1 cylinder are closed and PISTON is at TDC --NO slop allowed. if flywheel TDC mark does NOT line up ? --we make a NEW mark,------tolerance on PISTON TDC ? here we accept nothing more than 10 thou Amerikan inch. NOW the belt can be put back on.

Und zu weiter.

hagar.

[jason]

I guess you guys have answered my question; I kind of figured everybody would say that no deviation from TDC is acceptable, I just wanted to make sure I was not being too picky. I'm going to give it another go right now, I'll let you all know when it roars to life.

Thanks

[Fatmobile]

I've never used an injection pump gear locking pin.
Never seemed like there was a reason to lock it down.
If the crank is at TDC the injection pump timing marks need to be close,... it's nice to center the injection pump if it's not then take note if it has been turned all the way in one direction.
Like was previously said, get the injection pump close and the cam right on,... then come back and fine tune the injection pump timing.

[jason]

Hooooooo Yea! It lives! After over two years of having sat lifeless my Rabbit has finally uttered its first breath to its new life! Wow, I am so happy!!!! Thank you everyone!!!


Jason

[Fatmobile]

Glad to hear it's going.
Great feeling, when the smoke clears and it's running.
Another Rabbit back on the road.

[82vdub]

Congrats Jason. It's a great feeling when you resurect something from death's door. Great job!