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-   -   Quick question re Finding TDC... (http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/816521-quick-question-re-finding-tdc.html)

Nufy 06-16-2014 03:36 PM

Quick question re Finding TDC...
 
I am doing this by myself.

I have removed the dist and am using the cam line and notch to locate TDC.

Once I line those two up on the cam tower I check the inspection port at the rear for the flywheel mark.

If i don't see the flywheel mark I rotate one more time to check again.



Am I heading in the right direction ?

Thanks.

Slam 06-16-2014 03:52 PM

No need to rotate again if the cam's lined up. Just throw a 24mm socket on the crank and rock in either direction until you see the line and the OT mark through the window.

v2rocket_aka944 06-16-2014 04:44 PM

its a lot easier to line up the notch on the flywheel with the notch in the bellhousing next to the starter.

most cars the line on the flywheel is totally invisible.

Slam 06-17-2014 07:45 AM

That's true but I can't recall if Nufy's car is early or late. The early car's don't have that mark on the bottom of the bellhousing.

gtgt__bangbang 06-17-2014 08:04 AM

I think I see what you are asking; and it is the other way around.

The cam travels at exactly half the speed as the crank (just look at the relative pulley sizes sometime ).

think - It takes two crank rotations (intake+compression strokes and power+exhaust strokes, just to keep things simple) while the cam opens and closes the valves only once during that process.

When you rotate the cam from one TDC positioning, around again to TDC, the CRANK (and its TDC mark) have passed it's notch twice.

Align the cam and 'check' the crank but it should be there in a properly timed engine. Trust but verify

v2rocket_aka944 06-17-2014 10:42 AM

Quote:

Originally Posted by Slam (Post 8120605)
That's true but I can't recall if Nufy's car is early or late. The early car's don't have that mark on the bottom of the bellhousing.

i revived an 82 944 last year with the mark...and my early 85 has it as well...maybe its a mix and match thing,.

Nufy 06-17-2014 01:59 PM

Quote:

Originally Posted by gtgt__bangbang (Post 8120634)
I think I see what you are asking; and it is the other way around.

The cam travels at exactly half the speed as the crank (just look at the relative pulley sizes sometime ).

think - It takes two crank rotations (intake+compression strokes and power+exhaust strokes, just to keep things simple) while the cam opens and closes the valves only once during that process.

When you rotate the cam from one TDC positioning, around again to TDC, the CRANK (and its TDC mark) have passed it's notch twice.

Align the cam and 'check' the crank but it should be there in a properly timed engine. Trust but verify



So I should be at TDC with the cam marker lined up with the notch ?

I will still confirm by checking the notch on the flywheel and look to see if I have the notch in the by by the starter.

TXS.

Slam 06-17-2014 02:28 PM

V2 - interesting. Neither my 83 nor my 84 have it, but the 85/1 flywheel I used in wifey's car did have it.

I know it was an upgrade, and there's a tech bulletin specifically stating the dangers of using the wrong mark in the wrong place.

Back to the original issue: yes, if the cam mark is on, the crank is on or very, very close.

nightheart 06-17-2014 05:56 PM

wait a minute. Maybe I'm slow or don't understand something, but can you see the OT mark at all? Can't the cam mark be on, but the engine is at tdc on the exhaust stroke? A long extendable ratchet, a step stool, and a flashlight. You should be able to check the inspection port and rotate the engine around by yourself. It sucks and your arm will get tired, but when the OT is lined up than the cam marks, etc should be lined up.

gtgt__bangbang 06-17-2014 07:42 PM

night - no no and no.. one 360 turn of the CAM equals all four jugs done open & closed already, exactly one time. One cam, two cams, no difference. ( yeah each cylinder is on a different stroke -of the 4 possible- ) but there is nothing left to do internally (...after the one 360 turn of cam wheel) except do it all again, 6ooo times a minute preferably.


TDC to TCD (cam mark aligned , then back round-to cam mark aligned) = #1 closed at ~top of compression stroke back to #1 closed at top of compression. We dont care about the other cyls for timing work, they are all lock step . Watch some animations of 4 strokes.

marks on the flywheel / lower pully ie THE CRANK could be at TDC of compression OR TDC of exhaust stroke (two crank turns per complete cycle) , but not our faithful bump stick

Nufy 06-23-2014 06:40 PM

Success !!!
A big victory for me I guess...not so much for some of you seasoned 944 veterans.

TDC is reached...LOL

Cam Tower
http://photoshare.shaw.ca/image/9/5/...cam0.jpg?rev=0

Flywheel
http://photoshare.shaw.ca/image/9/5/...eel0.jpg?rev=0


Plus...my belts and pulleys have cleared canadian customs. if there wasn't a football game on Sat I would be elbows deep into this.

Soon...


Soon

Nufy 06-23-2014 06:41 PM

Another quick question...
The balance belt cratered inside the housing and left little pieces of itself everywhere.

Is it safe to spray de-greaser in the area to clean things before I install the new belts or should I be careful and use some detailing brushes ?

gtgt__bangbang 06-23-2014 08:23 PM

You can clean it. You should. Use the dgreaser AND the brushes to get all the rocks and goo out of the crevices.

Its a sealed engine; note that the timing belt cover is only partly closed, plenty of gaps to outside. That is partly why its so dirty there. That is also way you go very easy cleaning on a complete built engine, you might blow some dirt & oil down into the semi closed up time belt cover, not the best addition to a belt.

I mean its OK a belt get wet on occasion but I dont want chunks of oily grease up there

Don't power washer right smack into your seals ( I also put a few drops of oil directly on the seal lip after a clean up, just to re-lube the outside, don;t want a dry run on them)

Look around cover up any open holes ( like intake, water pump, etc). I wouldnt hose down my alternator too but ..

Slam 06-24-2014 07:16 AM

Good job, Nufy. That's TDC alright.

In my world, FIFA wins over FourFour too...

Nufy 06-24-2014 09:09 AM

Not much of a soccer fan but i do get caught up when a game in on in the pub.

Son and I are big Stamps fans though.

Slam 06-24-2014 09:14 AM

Oh, you mean American football... ;>)

Nufy 06-29-2014 08:10 PM

Belts and rollers done

Nice 60K shakedown run afterwards as well.

https://scontent-b-sea.xx.fbcdn.net/...01507917_n.jpg

pfarah 06-30-2014 08:25 AM

Good job...

Slam 06-30-2014 09:36 AM

Looks great! It's come a long way from the way it looked in that kijiji ad last summer.

Nufy 07-02-2014 07:07 AM

Its still a 50 foot car...lol

Gotta get it a bit quieter now...

Muffler and some exhaust gaskets me thinks.


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