924Board.org

[kylekev]

My son and I have been doing a complete rebuild of his 924 engine. Seals, bearings, gaskets, machining, rings, valve job, clutch, etc, etc, etc. This is our first motor rebuild and has been a huge learning experience. He went back to school and the project slowed down, but Dad is still making progress because we want to make it go.

The current problem is how do I know if the cam shaft is timed to the crank shaft. What I know:

1) The cam shaft is keyed to the upper timing belt pulley and the stamped dot is aligned to the the pointer on the cam shaft cover.

2) I found TDC of the number one cylinder by sticking a wire down into the spark plug hole until it quit moving up when I turned the crankshaft. It is pretty close.

3) The oil pump is assembled to the engine block including the timing belt pulley.

4) The V belt pull is not installed, have found the tiny notch on V belt pulley. I see there is a stud on the timing belt pulley that matches the extra hole in the V belt pulley.

5) I have found the the pointer on the oil pump.

6) With the number one cylinder at TDC and I dry fit the V belt to the timing belt pulley, it appears to be 180 out of position.

Because Kyle installed the oil pump and timing belt pulley, I do not know how it is aligned with the crank shaft/pistons. Looking at some exploded views on the internet does not show how the two are aligned so I do not know if the timing belt pulley is installed in the correct place on the crankshaft thus I do not know if everything is properly timed. Needless to say, I am being VERY cautious because I do not want to crash the engine because of improper alignment between crank and cam. We want to make it go, not OHHHH.

How do I know when the cam and crank are properly aligned.

And again, this is our first motor rebuild and has been a huge learning experience.

[Rasta Monsta]

There is a TDC mark on the flywheel you may find useful. Also, be aware that there are two marks on the cam pulley. . .you want to use the one that faces rearward.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[emoore924]

You might be 180 out because you've brought the piston to the top on the compression stroke, not the exhaust stroke, which is where TDC would be, and your cam would be inverted 180.

Align the backside mark on the cam pulley with the pointer on the Cam cover (as Rasta said).

Align the mark on the flywheel with the cutout in the bellhousing viewing port. To do this, rotate the engine CW slowly with a wrench on the crank pulley, watch through the port and you'll see the mark on the flywheel go by. IIRC it is a "0" on the flywheel.

If you really want to get fancy, you can align the dizzy rotor with the mark on the dizzy housing wich aligns with the #1 plug in the cap.

Ta-da! Now you've timed the engine completely...

[kylekev]

Thanks for the feedback. I am using the mark on the back side of the cam so that is good. Tomorrow night I will look work on finding the mark on the fly wheel. I assume there is no risk of damage when I rotate the engine. I am embarrassed to ask, but what is the dizzy?

[fiat22turbo]

On a non-turbo, no issue with being 180 off and rotating the motor. A turbo car could have pistons hit the valves, but at slow speeds it may not cause a lasting issue.

Dizzy=distributor (either ignition or fuel, heh)

Note: Make sure the distributor mounting setup is configured to the set of holes that lowers the distributor the max so that it doesnt hit the hood under acceleration, that is an annoying problem to fight.

Sounds like you're pretty close, but having the flywheel confirm you are at the right timing helps. There is a pointer on the front of the motor on the crankshaft, but you have to put the lower pulley on to use it.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[kylekev]

I hope we are pretty close. Install the intake, distributor, hook up the fuel lines, figure out some vacuum lines, plug in some electrical connectors, put in some gas and oil, and ....

[kylekev]

it appears I have been successful. the flywheel is on the notches and the the notch on the v pulley lines up with the pointer.

[pmcaya2]

It's a good idea to check the TDC mark through the fly wheel port. I wrote a short procedure called Timing Belt Alignment that is posted in the "how to" section. Hope this helps. Sounds like you're almost there. - Peter

[kylekev]

One last check because like I have already said, I do not want to screw this up.

When the flywheel is on the timing marks, in the viewing window, the front crank pulley notch is aligned with the oil pump pointer, and the cam dot is aligned with the cam cover pointer, WHERE should the number one cylinder be located. TDC on the compression stroke?

Also, where is the mark on the dizzy housing to align the rotor. I see a pointer that looks like a rotational indicator and a small 1/2 long mark down low on the housing.

I will do this tomorrow morning.

[emoore924]

If you do all this, #1 will be at TDC, which is just prior to intake stroke.

The mark on the dizzy is hard to see if you don't know it is there. Take off the cap and look on the circular top edge of the dizzy, where the cap mounts. There will be a small mark like someone filed the edge. That's it.

[pmcaya2]

Here's the procedure I recommended from the "how to" section. On a 2 liter you don't have to worry about valves and pistons colliding since it's a zero clearance engine. Here's the ho-to:

When you replace a timing belt or otherwise have to check timing, here's the procedure for a 924:

1) Turn the crank with a socket until the forward most (#1) cylinder is at top dead center with both valves closed - the nic on the engine pulley should be aligned with the pointer.

2) The indented dot on the back of the camshaft pulley has a dot which should be aligned with the nearby marker. (There is also an indented dot on the front which is not the right for timing.)

3) Place the belt around of the engine pulley without moving the pulley. Bring the right side of the belt over the camshaft pulley and work the cogs into the pulley. Bring the belt around the tensioner side and snug down the tensioner. Check crank/cam alignment and adjust the tension on the belt to allow less than 1/8 lateral movement on the long side of the belt.

4) Finally, with crank and cam aligned, loosen the distributor collar and adjust the distributor so that the rotor is aligned to the contact that fires the #1 cylinder. This should get the engine started and you might tweek the distributor for fine tuning. We used to call this "dry timing" when working on motorcycles.

[kylekev]

To quote Paul Harvey, this is "the rest of the story". Several days ago I was checking the TDC of the number one piston and it appeared to be off by 180 degrees. Remember the beginning of this thread where I talked about the pulley notch seemed to be off 180 degrees.

I have followed your advice to the letter and had everything lined up as everyone had coached me. A work associate told me to check TDC by sticking a coat hanger down the spark plug hole and rotate the motor until the piston came up and started to go down.

When I had lined up all the marks, the piston was at BDC. OMG, what did we do wrong. Shucks. Shoot. Son of a gun. So, as yesterday's posting said, I checked all the marks, rotated the engine, and nothing lined up. I was stunned. Dismayed. Crushed. You get the pic. I was a desperate man filled with negative thoughts.

It was then I noticed I was checking the number two cylinder.............,

Which of course, I then cracked open the number one cylinder, cranked the motor, and all was well.

I then cracked open a 6 dollar bottle of dark bourbon craft beer, at noon CST, I have been saving for a special moment.

And shared it with my wife.

[jim kleyh]

Hi from the great white north! Congrats, and thanks, your problems and the way you and the others went about solving them are why I get this forum. No smart a** comments just good qeurries and tech advise. This thread will help me BIG time shortly, JIM
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oldcarman-77 porsche 924 and one of the ugliest motorhomes on earth.