This is only from what Ive learnt myself by actually doing it, so might be slightly wrong :?
Shimming...first find out the clearances and whether its done hot or cold, I think the r is hot, Ive only ever done them cold so dont really know but i imagine you will have to warm it up, whip the camcover off and measure the clearances before it cools...bit impossible if you ask me :roll:
You have to measure the clearance between the lifter and camshaft lobe using feeler gauges. Measure when the lobe is fully off the lifter. This should be when the lobe is pointing directly away from the lifter (but some lobes are not symmetrical, use a feeler gauge to check this). Once you have measured and noted all the clearances you have to then remove the camshafts, remove the shims from the lifters KEEP THEM IN ORDER and measure the shims (electronic verniers are great for this, can get them for around £30 now). You then have to work out what sized shim you need for each lifter to make the clearance to spec. eg if the clearance should be 0.3, is measured to be 0.5, and the shim is 2.5, you will need a shim off 2.7. You can buy individual sized shims from Nissan but youll prob wait ages for them all to come in....the last one I did I brought a set of the largest that I could buy then got my local machine shop to cut them down to the exact size....you can also reuse some of the shims in different places if they are the right size. Maybe a good idea to find a knackered head and pinch the shims :?: Then box it up, warm it up and recheck the clearances.
Feel free to correct me anyone......
