Just out of interest, could I use the old followers, cam and bearings? I know I have new stuff, but I’m just wondering…
Assuming the old tappets haven't worn flat and the cam lobes haven't worn down, yes. New bearings would be better.
Ok. I’ll go with the new. Still don’t know why there’s only one thrust bearing as standard and not two. Two makes more sense to me…
...but not to VW who designed the thing . There's not a lot of thrust on the cam. My engine's only got one and it's fine. Cam: the lobes might be worn down, but appear ok. Can't find any figures on how tall they should be. Compare a used cam with a new one, and it's obvious, even though the lobes look ok. You will be losing valve lift if they're worn. If you're using Silverline bearings, make sure the thrust one isn't a press-fit on the cam. Might need some gentle sanding down to give the right clearance/end play.
I used a aftermarket cam and discovered the thrust bearing is too tight, so lathed the rear of the (big round bit with the gear) into spec, instead of rubbing the bearing down as that can cause the lip to separate from the shell which in turn will go up into the barrel and that’s that.
Sometimes with bearing clearances the difference between too tight and just right is only a tap of the hammer away.
Believe me, you wouldn’t have been able to hit the problem out of this one. Yes, sanding is an answer, but personally, I’m not sure that thinning a thrust bearing by sanding, however even, is the right way to go, when just a tiny bit of metal removal from somewhere where there is more material, is strictly sound, in an engineering sense. But I’m just an amateur as this engine building. I asked a 92 year old Articifer (?), who rebuilt the gearbox for H.M.S Norfolk in 1982, after doing a Full Power Run, ( a full power run, is done once a week, to test the integrity of the engines/ gearboxes and fuel delivery systems, in the ship, apparently. Who knew?),to get Prince Charles home from The Falklands, when he was in the Navy, about bearings, and my quandary. “Bearing 30 and 31, in the ships gearbox, was showing signs of breaking down due to uneven heat transfer, but I gave the All Clear, just to get him home. Next day, we rebuilt the gearbox, as it was ready to blow. I imagine my name would have been mud, in the newspapers, if we never got him back for his appointment”. Gotta love old people’s great stories. But I told him about ‘ making the bearing smaller’, and he said it would be better to do what I did, because of the heat transfer issue, and the now thinner wall of the bearing. Now I know this is just another opinion, and there are vast differences in the vehicles/ ship we are on about,and I value everyone’s. But I found it of interest, but principally, are the same, but scaled down. And I’m not overthinking this, just going on other views. I’m inquisitive….
It’s usually the (Silverline) bearings that are wrong, not the cam and all you are doing is reducing the bearing width to what VW designed it to be in the first place. But a nice story from your old chap, I’m sure I’ve heard something similar from Scotty to Captain Kirk. Incidentally, it’s always better to modify the cheap and replaceable part. Your way works but when someone replaces that bearing they might wonder why there is too much clearance.
I think the aftermarket cam was he cheap part. It fitted how it should of,on the old cam, hence my question about using the old cam…
What about a straight gear cam and dizzy drive. Would that have a double thrust, what with more for and aft, hence the whine? ( I like that sound).
