Idle loping on QV

The only thing that comes to mind is maybe, just maybe, one of the belts was replaced where the cam is slightly out of timing with the flywheel. That's the only thing I can think of...

When I did mine this past winter, I manually rotated the engine multiple rotations with the belts and tensioner fully engaged just to verify that I had everything timed correctly.

 

if the belt was replaced without adjusting the pulleys i.e. moving the pin then you could be off by one tooth which is 12*. which direction that's in, i don't know. not that replacing the belt without adjusting the pulleys is going to cause this problem, just pointing out the amount of degrees each tooth is.

you've also done the fuel system too, another posibilty is an injector not working right to a missing spark.

 

When I did my belts, I had to pull the pins on both cam sprockets and reset. The belts get stretched just enough that this becomes necessary.

Do to the belts properly (I apologize if this is the process you went through), you need to see how far out of spec the flywheel marks are to the cam journal marks. One person needs to be looking at the cam sprocket teeth to gauge the sprocket rotation that needs to be reset so the flywheel marks and cam journal marks are aligned.

It's a somewhat tedious process that really requires two people to do. One to rotate the flywheel crank the 2nd person to watch the cam sprocket groves. For example, it may be determined that the rear-bank cam sprocket needs to be rotated backwards (retard timing) 1/2 tooth. Note the sprocket tooth marks in relation to a mark on the cylinder head and then find a pin location that rotates the sprocket 1/2 tooth backwards and replace the pin. Make sure the cam does not rotate / move. Replace the belt, release the bolt on the tensioner bearing, tighten the bolt on the tensioner bearing when the bearing is "fully engaged". Now, rotate the engine to see if the marks on the cam journal and flywheel align. Don't be discouraged if this takes 2-3 attempts. The goal is to get cam journal marks dead-center in the goal posts on the cylinder head.

 

if your pulling off the cam covers you might as well locate TDC and re-align everything. the biggest pain is breaking free the bolt that holds the pulleys on. personally i just pull out the cams and undo the bolts. it also alows me to check and re-shim if need be without prying on the cam.

 

the QV has two marks on the cap? that would give you a few degrees of missalignment.

 

Yes, on the QV @ the cam journal, there are two marks and the goal is to locate the timing mark on the cam between the two marks (goal posts), ideally dead-center between them. The marks are so close together that it really takes either really good luck or multiple tries to get it dead center. To get both the front and rear cams all within the goal posts when the flywheel is at TDC is huge feeling of accomplishment.

 

Remember, it's not that the cams moved when you had them clamped, its the fact that they were probably already out of spec, albeit slightly, with the old belts. Since the old belts and new belts will have a slightly different length (not by much, maybe a few tenths), putting the new belts on without re-timing the cams may make it worse. You can't re-time the cams with the old belts because of the very small belt length difference.

 

Dave,

I had someone helping me with my major (actually, he was the previous owner of the car and my good friend) and he went through all of the nuances of doing the major service. Don't get down on yourself, a major is not the easiest of services to undertake.

I'll PM you my home number and you can call tonight if you have any questions.

- Greg