TDC Trouble

[RedPorsche]

Hello fellow PelicanParts users,

I am currently in the middle of swapping engines on my 1987 924S. Earlier this year, i suffered a number 2 rod bearing failure as well as collapsed lifters. I sourced a new engine for the car but unfortunately the previous owner had painted the cam tower as well as the intake manifold in a coat of white paint. Seeing as how the color looked absolutely disgusting on the engine, me and my brother promptly pulled these two bits and painted them in a more appropriate manner.

My troubles arise in that in my haste to rid the engine of the awful paint scheme, i forgot to set the engine at TDC before removing the cam tower. Now, I've searched this forum as well as Rennlist endlessly to try to figure this thing out, but all the TDC posts I've encountered either had the engine still in the car where TDC could be checked via the window on the bellhousing or via the alignement marks on the camshaft sprocket.

So my question is, how do I set TDC on the engine if its out of the car and if the cam tower is off?

Thanks

I've also attached photos of the engine and the car as it sits. I don't know if it uploaded correctly, I'm still pretty new to the forum.

[mikepellegrini]

There's a mark on the flywheel that lines up with a mark on the back of the block; it's been a while so I forget precisely where. Seems like it was fairly obvious.

You can also check by the position of the number 1 piston. When the engine is on TDC, both valves are closed and the piston is on top (which you can check with a straw or something flexible that won't mar the cylinder walls).

[Bradical]

it should be very simple- remove the spark plug for cylinder 1

[RedPorsche]

Thanks for the replies guys!

I was aware of the sparkplug technique to check if the number one piston is at TDC, but I was wondering if it would be accurate enough when installing the cam as well as the cam belt?

Also, you can see in the second pic (the one with the flywheel) that there is indeed a timing mark on the back of the block, but where is the alignment mark on the flywheel?
I've looked it over, gave it a clean, looked it over again, but can't seem to find the OT mark. All that I've managed to find on the flywheel was an inconsistency in the size of the teeth for the starter. I'll attach a pic.



As you can see, the flywheel teeth seem to be of equal size on either side of the inconsistency, then when it nears it, it appears that the tooth on either side gets significantly larger before a gap in the center that seems larger than the other gaps between the teeth on the rest of the flywheel. Would this possibly be the timing mark?

[thomasryan]

those are sensor teeth...not for the starter.

[Bradical]

the ring gear on the starter goes on the pressure plate, not the flywheel. What flywheel is that? Is that an S2 flywheel? It doesnt HAVE an OT mark on it.

The sparkplug method would sufice brilliantly as long as you are careful to get the crank set to top dead center, and realize that a 5deg rotation in either direction barely moves the piston.

In reality you can install the motor first, use the bellhousing to locate TDC and put the cam tower on after that.

[RedPorsche]

Thanks for the info Thomas. But does anyone know of a way to set TDC while the engine is out? Since it would be easier for me to put the cam and balance belts on while the engine is out.

[Bradical]

I suppose if you keep asking I can keep telling you that you have to use the sparkplug hole when the engine is out.

[RedPorsche]

I know Brad, but as you can see in my other post, I just want to know if the sparkplug tek will be accurate enough, since I don't want to bend some valves on start up, how do I know that I am EXACTLY at TDC? Correct me if I'm wrong, but I am a bit skeptical that a stick in the sparkplug hole will be as accurate as the timing marks. Not that I seem to have any other choice to get TDC on cylinder 1

[RedPorsche]

Just saw your post Brad. The flywheel is the same one that came with the engine that I sourced. I was thinking also about installing the engine to get the TDC marks on the bellhousing, I was just wondering if their was an alternative solution, since it would be easier to put the belts back on if the motor is out than if its in the car, where I'd have to maneuver between the radiator and the engine.

[Rasta Monsta]

Originally Posted by Bradical

I suppose if you keep asking I can keep telling you that you have to use the sparkplug hole when the engine is out.

Stupidest TDC indicator EVER.

[Bradical]

You can literally shine a flashlight into the sparkplug hole and see the top of the piston. Get it as close as you can and rock the crank back and forth until you are dead center. Super easy. Throw the belts on, turn the engine to the marks and double check your work. If you did it right you wont have to worry about touching the belts when the engine is installed

[kdjones2000]

The way that I do it in your situation is to place the sensor bracket into position on the block (by hand is fine), and look down through the holes in that rotate the engine such that the TDC pin on the flywheel is aligned.

This gets you within a tooth of TDC, which will allow you to assemble everything on the engine stand. Once you get the bellhousing installed (and maybe even the engine in the car), you can make a final check on whether or not you got it correct.

I have been correct 4/4 times so far, so it seems to work okay.

Good luck...

[944 Ecology]

The flywheel on that engine will not work with an 8 valve 944, it is for a 16 valve car.

Bradical is correct, the best way to determine TDC with no flywheel is via a wood dowel in the sparkplug hole of #1 cylinder. The best way to avoid bending valves when installing the camshaft on a 944 is to have the crank at 90 degrees from TDC (all pistons will be at about halfway down the stroke), install the camshaft, set the camshaft to TDC on #1, then rotate the crankshaft (slowly) to TDC on #1, install the belt and tension it.