Captain Sweeney

So i got the cam covers open, took out the plugs, and have found top dead center on cylinder 1 by turning the crankshaft bolt. What do i do now? Where should the cams be aligned to? Every time i turn them because of their shape they snap into the next position, so is the actual correct timing this flat position, which is one out of 4 possible ones? Or is it an in-between one, where I have to push down on the cam gear a little before putting on the belt?

If it's more complicated than that, is there a way to find a top dead center on the cams? Or some position where it's flat so I don't have to torque each gear before putting on the belt? I'm really lost here.

Oxnardo Ring

Here, this is the most comprehensive guide... is from Paul's site and it works back to the ABZ engines that lacked the cam index holes.
I'd sit down with this, with at least two adult beverages, and walk through it.

audipages Timing Belt Replacement

Paul keeps a good resource updated over there at audipages Home
You'll probably want to go browse, but this is probably the most complete guide to getting an ABZ cam back in order.

Captain Sweeney

Thank you very much

Captain Sweeney

So I looked through that and that guide assumes your timing is correct in the first place, which it isn't. Is there any way i can locate where the cams are supposed to be located by looking at them and moving the gear manually, not just locking the previous position in place?

silverd2

Oxnardo Ring

SilverD2 (he's seen it all) posted the timing mark location from the Service Manual. That's about the only way, since the timing belt sprockets are not indexed.

Paul's document mentions the "old" clamp (circular) tools to lock the cams in place, too. They are difficult to come by these days, so you'll probably have to come up with another means (Amazon sells generic cam lock tools) to fix the timing in place as you re-assemble. Good luck. I still kinda prefer the ABZ to the newer AUX and others. Audi didn't really get much power out of the 5th valve.. and their first-gen VVT scheme was lame.

Captain Sweeney

Dude, thank you. I still might buy the repair manual just so I can help other ppl out, plus fix stuff with less stress myself.

Captain Sweeney

Thank you very much. So with this, just to be sure, I align both cams to those marks as well as the crankshaft to TDC and I'm golden?

Oxnardo Ring

Yep. As long as you are TDC on #1 on the compression cycle, that's where they align to.

As we noted, it's a weird engine in that the sprocket can spin on the shaft without indexing or a keyway. So, yep, you have to go off the marks.

BrianC72gt

Are those cam marks TDC on 1 or TDC on 5? I know the crank lock for timing service is supposed to go in at TDC 5. On the 40 valve V8, Cylinder 5 is the front right one when facing the engine (on the coolant reservoir side). Regarding the cams moving while trying to set time, If you have the crank lock in, and are standing in front of the car facing the engine, then apply slight counterclockwise pressure to the left cam to remove any timing belt slack. That is your timing. The engine rotates clockwise when viewed from the front, all of the belt slack should be between the left cam and the crank cog. That is the span where the tensioner is located.

The fact that the cogs are not indexed is a good thing, it allows you to degree the cams very precisely. I know someone here uses this feature to dial their fuel trim down to zero. Very clever. Back in the day, I'd drill slotted holes in cam chain sprockets on japanese in-line four motorcycle engines to degree my cams. The tapered camshaft snout on the 4.2 engine allows you to do the exact same thing. Lock the cams in place, pop the cogs, snug them counterclockwise, and your timing will be dead-nuts spot on.