[s-cars] CPS mounting boss changes in early 92 - 93 AANs

[David Forgie]

Er, ah, Ben, I think you may have been "had". The RS2 engine, the ADU, is an evolution of the UrS4
 AAN and S2 ABY.  The RS2s were first built in March 1994 and were well past that AAN early 
build date transition from 3B (distributor, single coil) to the AAN with the CPS behind the cam 
sprocket.  The current PN for the AAN head is 034 103 351N, the same as the RS2 head.

Sounds more like you have a 3B or 7A head with the distributor hole blanking plate installed.

Photos and any PNs in the casting would be interesting to see.

The contact for the fellow with the CPS boss for a 7A head is

Rune at:  runeparts att hotmail  dotty com

Dave F.

----- Original Message -----
From: Ben Swann <benswann at verizon.net>
Date: Thursday, July 31, 2008 7:47 am
Subject: CPS mounting boss changes in early 92 - 93 AANs
To: forgied at shaw.ca
Cc: 'Ben Swann' <benswann at verizon.net>, "'Akiska, Erol'" <eakiska at uncc.edu>, s-car-list at audifans.com

> 
> Dave,
> 
> I can't answer your question, but do happen to have a version of 
> the head you describe.
> This supposedly RS2 head differs from the AAN head in that there 
> is no mounting boss for
> the Cam Position Sensor as on the AAN head.  I have both 
> side by side.  The distributor
> port is blocked off with a circular cutout, but I don't see how 
> either distributor or
> front mounted hall would have been used. I think this Ear;u RS2" 
> head is the same or
> similar as the one you have shown with the CPS boss - where do I 
> get one of these?  I
> see you mention it below - contact info?
> 
> I don't know if I can even use a distributor with the RS2 intake 
> manifold or not -
> haven't tried.  Tuna can?  Is that like an abbriviated 
> distributor with hall pickup only
> in it?  More info. please as I am looking for alternatives 
> for this head.
> 
> Ben
> 
> [Date: Wed, 30 Jul 2008 11:07:59 -0700
> From: David Forgie <forgied at shaw.ca>
> Subject: [s-cars] CPS mounting boss changes in early 92 - 93 AANs
> To: s-car-list <s-car-list at audifans.com>
> Message-ID: <cfb6d7695b2e3.48904b8f at shaw.ca>
> Content-Type: text/plain; charset=iso-8859-1
> 
> As you know, the cam position sensor (Hall sender) on the AAN 
> engine is typically
> mounted on the head, behind the exhaust cam sprocket.? 
> Exceptions are the very early
> AAN's that used a vestigial (tuna can) "distributor" at the back 
> side (intake side of
> the engine), driven off a gear on end of the intake cam. That 
> was a carry-over from the
> 7A and 3B engines (which had full distributors).
> 
> Up until yesterday, I always thought that when the CPS moved 
> from the tuna can, to
> behind the cam sprocket, the mounting boss was cast into the 
> head.? NOT so.? There is
> evidence (as shown in the link below) that the factory used up 
> some 3B heads by
> supplying a separate mounting boss that was bolted to the head 
> (and then the CPS was
> bolted to it).? I am curious as to when this practise started 
> and stopped, based on
> build date.? So if you have such a non-cast boss, can you please 
> post your car's build
> date?? (Thanks).
> 
> Photo of the add-on CPS boss (note - no PN in the FA for this):
> 
> http://forums.audiworld.com/s4s6/msgs/231574.phtml
> 
> Here is a photo of the "normal" cast CPS-mounting boss:
> 
> http://forums.audiworld.com/s4s6/msgs/231588.phtml
> 
> This all came up because a fellow in Norway has developed an add-
> on boss that will
> permit 7A heads to be used with normal AAN CPSs.
> 
> Dave F. ]
>