[alfa] 164 Motronic Cam Timing Mystery

[Dio Genio <diogenio@xxxxxxxxx>]

Digesti:

I am dismantling a 3.0L, 164 engine for rebuild/
transplantation into my Milano Platinum. I plan to use
the Motronic EFI that came with the new engine, rather
than keep the old L-Jetronic. 

The Motronic uses a toothed crank sensor wheel to
determine crank position.  On the circumference of the
tooth wheel, there is an area without teeth present,
an intentional gap used by the Motronic magnetic
sensor to recognize one complete crank revolution and
also crank position.

In trying to learn as much about Motronic as much as
possible, I rotated the crank until the two cam
reference marks lined up with the cap marks, and CYL
#1 was at TDC, with both valves fully closed. I then
expected the "gap" in the tooth wheel to be directly
aligned with the magnetic sensor (which is located at
the 3 o'clock position when facing the crank pulley).
Much to my surprise...it was not lined up! Rather, the
"gap" was facing downwards at approximately 7 o'clock.


My first thought was that the cams were terribly out
of time, perhaps due to a skipped timing belt.
However, the T-belt was tight and the tensioner was
still functioning properly. The engine came from a car
that had a front-end collision, but it was not bad
enough to damage any of the engine components.

I now wonder why this seemingly strange timing is so?
I also wonder how on Earth I am supposed to properly
re-time the cams if I remove them? Without the crank
pulley tooth "gap" referenced to anything, I'm bound
to get it wrong.

There's something to be said for the old L-Jet with
it's TDC mark etched into the pulley! That made life
(and cam timing) rather easy!

Any experts out there who can explain the Motronic
timing scheme to me?  

Thanks,

Dennis
San Diego 



	
		
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