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steeny

i promist i searched, and read haynes, but couldn't find it written exactly the way i want to hear it.

on the flywheel there are three marks, +10, 0, and -10. now i assumed -10 would be BTDC, and +10 would be ATDC. is this correct?

Initially i set the flywheel at 0, and the cam gear at TDC, and installed the timing belt. apart from having trouble getting the car to idle high enough (800 seems about it), i set it all at -10 the other day when warm, then when i went to start it today, i couldn't get it to start. and it would only idle if i held the peddle all the way down, so no revving.

i had to adjust the dizzy to get it to start, and once it warmed up the timing light was showing somewhere back near 0.

so am i setting it at the right place? or is there something else i am doing wrong?

any help will be appreciated

cheers

ps. i'm quite happy to set it up for 98 octane petrol. i'm not scared to use lead aditive in each tank either, so if this changes how its set up, please let me know.
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1978 924 N/A
she's gone.....

Ozzie · Posted: Wed Jan 17, 2007 9:48 pm Post subject:

I forget which one is which.
When you are turning the motor CW by hand, the first mark you come to will be BTDC, then TDC and ATDC.
I have read that the head has hardened inserts so doesn't need lead additive but you can add it if you wish.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Don't forget you have to time three things: the crank, the cam AND the dizzy...

Joes924Racer · Posted: Thu Jan 18, 2007 4:56 am Post subject:

Oz is that looking from the drivers side window down into the
timing site hole. I think he know about intial timing.. as in
setting up the belt he jusy wants to know where the runs best
mark is.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Ozzie · Posted: Thu Jan 18, 2007 6:59 am Post subject:

oops double post.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Ozzie · Posted: Thu Jan 18, 2007 6:59 am Post subject:

If its a euro/ oz vehicle it is set at the first mark he comes to. BTDC
If it is a US import the Haynes has reference to different models.
If he is using anythning less than 98 ron he would have to retard it a little and run about 5-6 deg BTDC.
If it is hard to start and run then look at fuel mix, injector spray pattern, vacuum leaks, CSV, AAV and WUR.

Yep I mean the flywheel mark as seen from the LH side under the brake booster. While looking at the motor and rotating it CW the first mark is BTDC.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

steeny · Posted: Thu Jan 18, 2007 8:47 am Post subject:

ok, i think that means that +10 is actually BTDC. doesnt' make any sense, but i'll give it a go today or tomorrow when i get a chance.

also, since i cant reach my battery with the timing light leads, it doesn't hurt to run it of another DC source does it? i assume any 12 volt source is good, as long as the trigger wire is on #1.
_________________
1978 924 N/A
she's gone.....

leadfoot · Posted: Thu Jan 18, 2007 5:34 pm Post subject:

??? you should be flashing the timing light into the bell housing inspection hole, battery is right next to it, then reach across to turn ignition dissy,
where are you flashing it ???
leadfoot
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

steeny · Posted: Thu Jan 18, 2007 5:59 pm Post subject:

thats where i'm flashing it. i have three marks on the flywheel. +10, 0 and -10. my battery isn't there anymore though, its in one of the rear wells, cause i had some rust and water leaking problems. that also means that the leads for the timing light wont reach all the way back there, and onto the number one lead, so i am using a spare battery to run the timing light.

i've adjusted the dizzy so that when the car is warm, the flashing strobe lights up just between the +10 and the 0 marks on the flywheel, and it all seems to be working for me. i assume this is aroung 6-8 degrees btdc, which i think is right for 98 octane fuel
_________________
1978 924 N/A
she's gone.....

Ozzie · Posted: Sat Jan 20, 2007 12:16 pm Post subject:

When I set the timing the strobe is set on the bellhousing mark but I also check the other 2.
The cam gear is 1/2 (5 degree) because it rotates at 1/2 the speed of the crank.

_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

geddes66 · Joined: 10 May 2003 Posts: 129 Location: Bakersfield CA

I do not know either BUT... you should be able to tell when looking at the engine. Note which way the engine rotates, the mark after 0 as it rotates is the after mark. No way to get it wrong.
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The Porsche is now my son's, my car is cooler, slower but cooler.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Well, when looking at the engine from the front, the tensioner is on the left side of the timing belt path, so the right side is getting the pull, therefore the crank is turning clockwise.

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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

geddes66 · Joined: 10 May 2003 Posts: 129 Location: Bakersfield CA

Look at the alternator. The alt fan will give it away. I think it is clockwise too. My 924 is broke (stuck in 2nd) a hundred miles away or I would go out and look. Now find the "0" mark and rotate it a known direction till you see the other mark.
_________________
The Porsche is now my son's, my car is cooler, slower but cooler.

leadfoot · Posted: Sun Jan 21, 2007 9:26 pm Post subject:

engine rotates clockwise...
0 degrees at 850 +/- 50rpm is correct but...
Running an extra 10 degree advance on 98 octane is better...

If it's just starting problems then it sounds like your air/fuel ratio needs to be set. I would set timing at the right figure and adjust the fuel dissy a quarter turn clockwise at a time (to richen the mixture) and see if it will fire up, use a 3mm long allen key. If you can get it to idle and your exhaust doesn't look way to rich by having excess black smoke then you should be right, otherwise get it going and take it to a garage to have it's air/fuel set.
Leadfoot
_________________
1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Ozzie · Posted: Mon Jan 22, 2007 12:39 pm Post subject:

Ok Steeny I have a couple of urethane bushes for your alternator- Forgot your address?
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance