911/83: help needed in setting up ignition timing

[Biancaneve]

We're in the process of fine tuning our Carrera 2.7 engine after some work we've done during the winter but we're a little puzzled: apparently there is some mismatch between the indications of the tech specs booklet and those of the workshop manual: according to our reading, in the former (booklet), the ignition timing at idle should be at 5deg atdc, whereas in the latter (w/s manual) is shall be at the tdc (i.e. at Z1). Are we missing something? Last time we did it maybe it was 12 years ago ... can't recall exactly how we did it ...

Thanks for you help

[Jon B]

Your Tech Specs booklet is the 1974 edition.
The specs in this booklet refer to the Carrera CIS engines 911/93 and 911/98, not to the 911/83 Carrera RS engine.

The 1973 Tech Specs booklet shows a different ignition setting for the 911/83 Carrera 2.7 at idle.
The Bosch distributor listed for a 73 Carrera is 0 231 169 011, or 61015155 for a Marelli.



Jon B.
Vista, CA

[Biancaneve]

Thanks a lot, so it refers to the US CIS Carrera, not the ROW MFI Carrera! Dumb I was!

[uai]

Massimo, I would adjust it to the max. at the given max advance RPM.
Ignition timing at idle is only useful to get it running, but you do not want it to be too early when being under load or at high RPM.
So I always verify that max advance is correct.
Cheers

Uli

[Biancaneve]

Massimo, I would adjust it to the max. at the given max advance RPM.
Ignition timing at idle is only useful to get it running, but you do not want it to be too early when being under load or at high RPM.
So I always verify that max advance is correct.
Cheers

Uli

Yes indeed, the booklet has the reference values up to 6000 rpm, we'll check all of them.

Thanks a lot

[Jon B]

For reference, here is the original ignition graph for the Model 73 Carrera RS 2,7 ltr. engine, with vacuum disconnected.



Jon B.
Vista, CA

[Biancaneve]

For reference, here is the original ignition graph for the Model 73 Carrera RS 2,7 ltr. engine, with vacuum disconnected.



Jon B.
Vista, CA

Thank you!