Actually this curve is not that far off for a 911.

Grady,
Is the vacuum retard strictly for emissions or does it help at start up? I always thought retarding timing helped starting due to the piston is on the down stroke.

If it's for emissions only, would we be better off eliminating and plug vacuum line, time to 35 deg at 6000 and adjust idle and AFR?

Thank you Grady et al. I printed out your detailed instructions and put them in my (crappy) Bentley manual. I am not certain I can get all over the removal at this time but I do have an hour or two Saturday to check the timing and dwell. Thank you again - what a resource!

Brilliant thread! Finally got my idle to 800 rpm after cleaning throttle body and correlation. The light shows exactly 5 BTDC at idle and 35 ATDC at 6000rpm. Only worry is that I had to push the distributor to the end of the range. Is that a problem?
http://forums.pelicanparts.com/uploa...1306589816.jpg
http://forums.pelicanparts.com/uploa...1306589844.jpg

Are you sure you have the injection pump timing right?

Thought so, will check again.
Car drives very well!
Ed

to clarify...
 

Thanks for this great thread pelicanites....

I would like to clarify if information below is correct, when setting idle:

-IDLE timing should be at 5 deg ATDC (Vacuum Hose ON)
-Timing at 6000 rpm should be 32 to 38 deg BTDC (Vacuum Hose OFF)


thanks

Yes that is correct for the motor (2.4T/E) in this discussion.

You should, however, consider the gas you have available and the driving conditions. In California with the 87 octane gas (regular) we have available 38 deg @ 6000 might cause detonation on a hot day if you are redlining your motor. If you don't ever redline your motor then I wouldn't worry about that much advance on a stock 2.4T. You could also switch to premium and that would allow you to go more aggressive on the advance.

Also, if your motor is modified then that has to be taken into consideration. If you have high compression pistons, for example, that has to be taken into consideration for what kind of gas and advance curve you can run.

The Best
 

Thanks Grady, you have taught me a lot on here.

Bill

I'm probably looking at this picture of the timing marks wrong, but if I rotate the crank 120 degrees to go from cyl 1 to cyl 6, are the marks identified for 2 and 5 reversed with 3 and 6?

Hi Grady

I'm working on bringing a 73.5 911 w/ an S engine (MFI) back into service after having sat for 4 yrs. I'm at the points/timing stage, and with dwell ~ 40, to get timing set to 5 ATDC the distributor is rotated nearly full CW.
With vac disconnected it does advance, but I'm pretty sure never to 35 BTDC (quick rev up to ~ 6k).

Might this suggest the distributor is off by a tooth or more?
Charles

http://forums.pelicanparts.com/uploa...1350255406.jpg

1973 911T 2.4 Timing marks
 

I'm replacing cables cap and rotor also points set on my 1973 Porsche 911t 2.4 mfi.
what are the correct timing marks on the pully with the timming light?
any tips?

So great picture. My question is if z1 is tdc for cylinder number 1 and the other two marks spread apart 120* are for the other cylinders, what are the two close marks together marked 30 and 35? When checking the timing at idle and again at 6000 rpm, shouldn't the z1 mark be what you are looking for in the light? Thanks

The Z1 mark is no more than Top Dead Center, "TDC" for cylinder #1. Nothing is ever timed at TDC, it only serves as a reference mark so that you can place either #1 or #4 at their respective TDC positions when setting the valve lash. It has nothing to do with ignition timing.

The "30" and "35" marks represent 30 degrees and 35 degrees Before Top Dead Center, "BTDC". These are used to time the ignition, the ones you should see lining up with the split in the crankcase and the little hash mark on the bottom of the fan housing when the timing light lights up.

The original specification was to have the ignition set at 35 degrees BTDC with the engine running at 6,000 rpm. That may prove to be a little too much advance, causing detonation, or "pinging", on today's gasoline. Lots of guys like to run 32 degrees BTDC, which you can kind of "guesstimate" using the 30 and 35 degree marks.