asiab3 wrote:
main bearing clearances
1- .002"
2- .0025"
3- .003"
4- .0025"
If you are a nutcase, please join me in a moment of sheer insanity.
#2 is supposed to be .0005" tighter than the other big bearings along the crank. This is the whip journal. While its overall clearances are mostly within the same range as the others, VW had a reason for tightening #2 down a smidge.
The insanity is to razor blade the mating surfaces of the saddles at #2. You have machining marks as reference. Go down evenly just enough to almost obliterate them, both case halves. Now grab a #2 main bearing half. It is coated with a dull lead grey. The edge, the edge that butts the other bearing half, you can carefully rake with a fresh clean razor blade. Do one bearing at the bottom, the other at the top. Just enough to see that the razor blade indeed has visited. We want the #2 clearance at least down to #1's clearance. I would probably also razor #3 down a tad.
Beyond the horrified expressions of revulsion from the Color Inside The Lines Brigade, we are trying to reduce the hammering and vibration that occurs inside the magnesium crankcase. Every bit of help we provide now when the engine is new, extends the day that the hockey stick graph catches up with you. That means, as clearances open up, the resultant damage goes up exponentially. If you should choose to embark upon this insanity, the need for cleanliness goes up commensurately.
Less clearance = greater damage from debris.
asiab3 wrote:
I'm missing one bearing dowel pin and one secondary case stud, (down by the cam plug,) so I'm visiting my old German friend to get them tomorrow. He also has quite a few gently used camshafts to try in my case with my crank if I'd like.
Dowels should be secure in the case. People will often blow this off because they cannot see the cure, "it doesn't matter!" The problem with loose dowels, is the bearings can move/fret in the case when the engine is hot, and this causes wear on the backsides of the bearings, which then reduces the "crush" which then opens up the clearances, which then allows more movement still, which allows more fretting, which reduces the crush still further, and eventually you have bearings that are ovalizing at the dowel hole and banging around in there destroying your case and eventually the dowel leaves the case hole and all hell breaks loose.
Find a good mesh amongst any of the camshafts available to you with your crank and your cam bearings.
Now read the number on the gear that has the best mesh.
A lightly worn camshaft with the gear of your choice may be able to have additional hardening treatment, or you can regrind the lobes to factory specs on a slightly smaller base circle (followed by hardening treatment). Camshafts work too hard to use off the floor used ones. You want new lifters that match the camshaft hardening numbers. If the gear of your choice is not available on the camshaft of your choice, you will need to grind off and bolt on. It is critical to do this job more than carefully.
asiab3 wrote:
My distributor drive pinion will not fit into my case. It hangs up about an inch and a half from being seated. Is there something I'm missing here?
Yes. This is not a new case is it? If it is, there have been reports of incorrect diameter down at the thrust washer end, which seems too low down for your 1 1/2" hang-up.
Crank is nowhere near, right? If crank is in, you MUST carefully wobble the crank back and forth and try to get the distributor drive gear tooth to slip past the brass ramp of the crankshaft gear. Really babysit this one. I have had to razor blade every entrance to the brass gear . . .
Itinerant Scissorhands
The Razor-Bored Crankcase (I did have to rake the entire saddles to make them larger)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles