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Please identify 1977 Carrera 3.0 timing marks

Hi,

Can anyone identify what these 4 marks are please.

I cannot see any identifying letters or marks on the face of the pulley.

Thanks

Bill

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1977 Carrera 3.0
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Old 12-05-2012, 10:25 PM
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clean off the front of the pulley and see if you can see a Z1 or any numbers. i just pulled my motor and finally saw that my timing mark was 35 degrees.
it can help to line the roto up to the timing mark on the dist if you can see Z1.
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86 930 94kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
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01 suburban 330K:: [__] RUNNING: [__] NOT RUNNING:
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Old 12-06-2012, 03:05 AM
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Quote:
Originally Posted by Bill Jennings View Post
Hi,

Can anyone identify what these 4 marks are please.

I cannot see any identifying letters or marks on the face of the pulley.

Thanks

Bill
From left to to right in the pic
the left most 2 notches are
5° ATDC 0(AKA Z1)

the right most 2 notches are
35°BTDC 30° BTDC

edited to correct for mis-remembered crank rotation
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'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
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Last edited by Bill Verburg; 12-06-2012 at 06:07 AM..
Old 12-06-2012, 03:23 AM
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I've already tried to have a good look with a mirror but i'll try some carb cleaner on it.
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1977 Carrera 3.0
This much fun must be illegal!
Old 12-06-2012, 03:41 AM
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Bill,

Many thanks I was reading them the other way round and that didn't make sense.

Any idea why the C3 timing is ATDC and most other 3 litre 911's are BTDC?

Thanks again

Bill
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1977 Carrera 3.0
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Old 12-06-2012, 04:36 AM
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What's interesting is that the 74/75 US Carrera spec book shows those marks as (left to right like Bill says) 5 deg ATDC, Z1 for the left pair, and 30 deg, 35 deg. BTDC for the right pair. The spec book for the Carrera 3.0 does not show the pully wheel diagram, and only lists 5 deg. ATDC for idle timing, and no timing number at 4000-6000 rpm. Why would there be timing marks for 30/35 ATDC?
Old 12-06-2012, 04:56 AM
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Quote:
Originally Posted by Bill Jennings View Post
Bill,

Many thanks I was reading them the other way round and that didn't make sense.

Any idea why the C3 timing is ATDC and most other 3 litre 911's are BTDC?

Thanks again

Bill
for '976-77 C3,
Idle timing w/ distributor vacuum connected is 5° ATDC
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Old 12-06-2012, 05:48 AM
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i was wondering the same thing. wouldnt the 30-35 degree marks be "BTDC"
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86 930 94kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
03 BMW 330CI 220K:: [__] RUNNING: [__] NOT RUNNING:
01 suburban 330K:: [__] RUNNING: [__] NOT RUNNING:
RACE CAR:: sold
Old 12-06-2012, 05:51 AM
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Quote:
Originally Posted by Gib Bosworth View Post
What's interesting is that the 74/75 US Carrera spec book shows those marks as (left to right like Bill says) 5 deg ATDC, Z1 for the left pair, and 30 deg, 35 deg. BTDC for the right pair. The spec book for the Carrera 3.0 does not show the pully wheel diagram, and only lists 5 deg. ATDC for idle timing, and no timing number at 4000-6000 rpm. Why would there be timing marks for 30/35 ATDC?
to check timing at max advance

earlier models were speced to either 30° or 35° BTDC @6000 rpm

I may have gotten the left/right thing mixed up as I don't really remember which way the crank pulley rotates

if it is rotating clockwise in the pic then the right 2 are 30° 35° BTDC

and the left 2 are 5° ATDC and TDC(Z1)
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Old 12-06-2012, 05:58 AM
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I used to put a bit of phosphorescent chalk on the 5° ATDC mark, it would fluoresce under a timing light making it easier to see.

It appears that there is chalk on the left most mark, probably for the same reason

which means that if the pulley is rotating clockwise the far left mark is the 5° ATDC
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Old 12-06-2012, 06:02 AM
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The engine rotates clockwise. Thanks for clearing up your previous comment, Bill, you comments are always on the mark, so I just was puzzled about that earlier comment.
Old 12-06-2012, 06:03 AM
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Quote:
Originally Posted by Gib Bosworth View Post
The engine rotates clockwise. Thanks for clearing up your previous comment, Bill, you comments are always on the mark, so I just was puzzled about that earlier comment.
It's been a looong time since I swapped that engine out

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Old 12-06-2012, 06:10 AM
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