cam timing for 911/81

shbop · 09-01-2007, 11:23 AM

I can't seem to find the cam timing specs for a 911/81 motor. Wayne's book has a void in that particular space. 1977 Carrera
Seems similar years of CIS use .6mm, but I'd like tyo be sure.
Does anyone know the appropriate specs?
Thanks in advance!

Eagledriver · 09-01-2007, 12:41 PM

Jon,

If that is the Carrera 3.0 then the cams are the same as the SC and 84-89 Carrera. There are 3 different settings for these cams depending on the year and port size. Early 3.0 Carreras had the timing set at .9mm-1.2mm. Many SC engines had the cams advanced to 1.4-1.7mm and the 84-89 Carreras set the timing to 1.3-1.5mm. If you have the big ports I'd use the retarded number (.9-1.2mm). If you have the smaller ports (34mm) I'd use the advanced number (1.4-1.7mm). A good compromise is to use the 84-89 Carrera setting.

If you have 2.7 cams then I can't help you. A useful upgrade would be to install an SC grind.

-Andy

shbop · 09-01-2007, 02:39 PM

Hi Andy,

Thanks for the reply. It is indeed a 2.7. It came with a 75' Targa I recently aquired. The motor number (911/81) was a bit odd, but in Wayne's book it shows it as a 77 model year 2.7 engine. Unfortunately there are no specs for that particular model. Does anyone know if .5-.7mm, with .6mm being optimum would be correct?

MBEngineering · 09-02-2007, 08:01 AM

HI Jon
The cam timing for 1976/77 engine's ;911/81, 911/82, 911/84, 911/86, 911/89, 911/85 are all 0.4-0.54 with cams L 911 143 00 and R 911 144 00.

the Carrera 930/02 and 930/12 is 0.9-1.1 with cams L 930 147 08 and R 930 148 08

regards mike

shbop · 09-02-2007, 11:22 AM

Thanks Mike. I set it up @.6mm, and now can't find the paper I wrote down the cam numbers on. Back-in I go.