Timing marks mk1 golf gti cabriolet

I'm about to put my timing belt back on my mk1 golf gti cabriolet… I've a 6* btdc mark on my flywheel and a tdc mark and I don't know which one to choose to set my car to before I put my belt on?? I have an arrow on my plastic lower cover etc too what do I do? 

Setting it to 0 mark is the way to go.

Crank to 0.
The Dimple on the back of the cam even with the valve cover tin (Not the rebar on top of the tin.).
Dizzy in the middle of the hash mark stamped on the case. (loosen the pinch bolt at the bottom)

Do not try to align the pulleys for the intermediate shaft, as it could of been off, it is best to rotate the shaft so the dizzy aligns.  Cap off, Rotor off, plastic shield off and reattach the rotor.  If your dizzy is in the proper position (usually 12:00-1:30) then the notch is on the block side.

See www.cabby-info.com as Kammy has pictures of the timing mark.

Digifant can be set timing to 950, and CIS to 750 RPM with a timing light at 6btdc.

There is a thread on how to time Digifant cars to 6TDC with nothing more than a DVOM.  CIS is a different story.

I've never used that mark for changing the cambelt.

Depending on what year your car is as the timing marks on the cam shaft did change on later car.
From my 1988 gti cabriolet.
I've painted the marks to make it easier to see when I change the belt.

You should not need to adjust the timing (move/rotate the dissy) if it was all ok before changing the belt, if the timing is out (engine running lumpy) when you put it all back together the you are 1 tooth out somewhere, it's usally the intermidiate shaft which goes out as that turns very easily when the belt is not on.

Without lower plastic cover on, when you remove the lower pulley from the crank (to remove the old belt) you must make sure you put it back on in the same position.



Cam shaft.


Lower plastic cover back on

 

There are pro's and Cons with the Intermediate Shaft and if the cover is on or off.  The issue is that with the cover on, you have to rely on Pulleys, and their marks.

The most simplest way is to align the Crank to 0TDC on the Crank.  Your rod Trick on the Head to Cam is Brilliant, I think it eliminates the "parallax" error, but I have used the Valve cover tin for years to no ill effect, albeit that the Bentley shows it as with the tin installed so with the Width of the Gasket and Tin, you have less than the desired setting.

The other issue is that you or the Mechanic who doesn't take the Lower cover off, to see where the marks are, can't rely on them for "being" correct.  

It is way better to error on the side of caution, than to assume.  I mean that even if you align the marks, you had better Validate that the Dizzy's rotor is in the correct position.  This is why over here we just "do" it.

Now I have a Digi, and the upper cover has a 0TDC on it, I normally set the rear dimple, then cross check the cover.  I still can see a "parallax" difference, in a Visual or a Camera, photo.  So I suspect it is subjective, not like  lining up a timing chain and holding a straight edge between the dots.  

Also the Crank can be 180 out from the Cam, and the Dizzy.  So it is best to error on the side of caution, than to make an assumption on a visual inspection.  

Everyone has a method of setting time that suits them.
Everyone doesn't do it my way or for the reasons that I have stated…. I try to use the K.I.S.S. methods for everything.  Keep It Stupidly Simple.

I also have been ingrained to work smarter not harder, and that sometimes, you have to inch things apart as that is the fastest way to do things.  I can recall wasting
a couple of hours to find a better way to remove a nut, than the one face turn at a time for a nut or bolt….

main thing if using the crank pulley is make sure the outer part hasn't slipped if its the damper type, I worked on a 2.0 8v mk3 and it was near 90 degrees out from where it should be. flywheel mark will always be spot on (unless a chimp has worked on it!) so I always use that if possible.

I never bother to check the intermediate shaft sprocket marks either, they can be way off if previous mechanics haven't bothered using it. I just take the cap off and line the rotor arm up to the notch on the dizzy, if the int shaft hasn't been messed with it'll be lined up, if not it wont be but who cares it'll run still

other thing to be aware of with the int shaft is it will spin freely once the belt is off, so easy to knock the dizzy out of time if you're not paying attention so keep an eye on that while you're trying to get the cam and crank to tdc

it can be a bit of a fiddle getting the cam and crank lined up, then fit belt, then tighten the tensioner as it can move about. my method is fit the belt as tight as i can between cam and cranjk, then slowly rotate the cam anti-clockwise till i can get a 90 degree twist on the belt. note the position of the marks, if out move it a tooth either way as necessary then try again. when its right then set the tensioner, rotate the engine 360 degrees clockwise and recheck marks and belt tension.

the smallest unit of movement either way is 1 tooth, so if the difference between cam and crank is less than that then its correct. Another thing to note take the spark plugs out, it makes rotating the engine much easier, and try to use the crank bolt to rotate the engine rather than the cam bolt