3b timing problem

[WidowmakerS2]

As a part of solving a puzzle with boost/fuel on a rebuilt Coupe, I've checked the timing marks a few times, but I can't make it seem right with the distributor timing.

The engine is (I'm told) a 3b, with a 7A flywheel and distributor.

Today I sat the engine on TDC (checked with probe in #1 cylinder), and lined it up with the camshaft sprocket timing marks. I did not check the bellhousing marks, but I did note that the vibration damper (or front crankshaft) mark didn't line up. (can be 180 out right?)

I checked that the two lines in the dizzy were in line, and that the rotor pointed towards #1 lead. Then tightened the dizzy down.

So far, so good?

Replaced all the stuff I had to get out of the way to get access, and went to fire it up.
It just cranked over, no spark.
After a few small adjustments to the distributor, it would fire up but did not run right.
I'm at a loss, what could be causing the engine to not start once timed correctly, but to start when it's not?

Could it be the flywheel pin on the 7A flywheel being off, so the crank, -and hall sensor windows don't overlap in 100% timed condition?

[Bowie69]

Well, the dizzy runs half the speed of crank, so you need to get this lined up properly on crank and dizzy. Forget about camshafts, assuming the belt was done properly then this is irrelevant.

[WidowmakerS2]

At this point I can't say wether the belt was done correctly or not, because the car had problems before trying to time it up.

[UrS4boy]

There are nice 3B timing photos in this post:

http://forums.quattroworld.com/v8/msgs/13192.phtml

[WidowmakerS2]

There are nice 3B timing photos in this post:

http://forums.quattroworld.com/v8/msgs/13192.phtml

Thank you!

The top two are the way i had it, but I checked the crank timing by using a probe down the #1 cyl spark plug hole.

[220bhp]

Two important things hear. One, If the alignment marks on the side of the dissy don't line up perfectly, you will not get full boost. You can try to do it with a mirror or a scope ,but to be honest you would be better to take the inlet manifold of, that way you can get to, and check everything properly. It is not to much of a job with the right tool.
A long allen key on a socket fits through the holes in the manifold.You don't have to disconnect the throttle body etc, just undo the manifold bolts,lift it of and tie it up to the bonnet. There are pictures on hear of how to line the dissy ,and the timing.
The second thing is to check the keyway on the crank pulley. If its had a cam belt done there is a chance the crank bolt was replaced without locktight, or wasn't tourqed up properly allowing the keyway to move enough to put the timing out,or if it shears of ,the valves hit the pistons. This is a common failure with the i5.

Good luck

[WidowmakerS2]

Well, this car did have some boost issues, but nothing like limp-home mode.

I agree on the crank keyway.

I can't find the pictures describing dizzy timing. At this point I'm starting to doubt even the most basic things, so anything would be of great help. I'm not working on the car today, so I have time to gather some information.

Ignition timing is 12453 ?
I'm pretty sure this had numbered leads, but i cant remember the way they were fitted.


Here's the pic of
the dizzy timing: (sorry it flipped over on the side)

I'm thinking, maybe the timing marks are lined up too far "up", and they should be lined up pointed towards the water manifold or something.

[quattrostyle]

I persume you already did the following but I would start with the basics (and also clean up the tip from that rotor)

1. Take plug no.1 out
2. Check the heigt of piston no.1 with a long screwdriver
3. Rotate the crank and guide the screwdriver so it doesn't get stuck
4. Stop at the point the piston is in top position (that's TDC?)
5. Check if the lobes on the camshafts at cil. no.1 are pointing upwards, indicating the valves are closed, if not loosen the cambelt, adjust the camshafts and tighten the belt again
6. Adjust the distributor timing as accurately as possible like in the pic you posted
7. Check the spark leads order with the timing order 1-2-4-5-3
8. Mount the distributor cap and start the car.

Regarding to the flywheel, 7A flywheels have been used on S2's to get rid of the dual mass flywheels so that shouldn't be a problem.

[UrS4boy]

...I can't find the pictures describing dizzy timing. At this point I'm starting to doubt even the most basic things, so anything would be of great help.

What do you mean, can't find pictures? The first picture in the link I gave you is this one:



Yours:

[WidowmakerS2]

I'm sorry urs4, problem must be on my part, the images in that Thread showed up as little boxes. I guess dizzy timing is code enough then, and the problem must be somewhere else.
Quattrostyle: Thanks for the writeup. At least I thought that's what I've done. Never encountered anything like this before.

[WidowmakerS2]

This continues to puzzle me..

Had the intake manifold off, timed the engine again, checked all the marks. A little trouble with the mark in the flywheel (rust), but checked with probe down #1 and vibration damper mark.

Then i took the distributor out, cleaned the rotor tip and put it back in, with the rotor facing towards the front of the engine, and the two marks aligned.

Tried to start it up, there was nothing. Just cranking over.
Tried to adjust the distributor a few mm up and down again, as it had worked before.
It fired right up.

Am I missing something important here?

My thought about the flywheel is that I've heard some people say that the G4 pin is moved on the flywheel on 7A vs 3b, hence why my hall -and crank windows don't match before i manipulate it outside marks?

[220bhp]

Have you checked the keyway on the crank pulley.

[WidowmakerS2]

Have you checked the keyway on the crank pulley.

I have checked that the bolt is tight, but I don't have any locking tool at hand. Wouldn't that affect timing marks aswell?

Crank pulley changed less than 1000km ago.

[OLD100]

Is the rotor arm turning in the distributor? if not drive gear on cam snapped

[WidowmakerS2]

Is the rotor arm turning in the distributor? if not drive gear on cam snapped

Yes, it must have turned. The car ran for a while.

Can you confirm what way 3-pin plug plugs into the distributor? Locking clip in or out?
I'm really checking out every possibility now.