Since 911SC does not have a chip, would advancing the timing help.
 

My operating manual says 1982 911SC can run on regular gas. If I will always run premium gas, at least 92 octane, would it help to advance the timing some for better perfomance?

try 35° total, 3.5% CO, oxy sensor unplugged forever. (except emissions testing)

John,
do you leave the O2 sensor unplugged because it will try to lean out the mixture at part-throttle, leading to pinging?

because they lean the engine out, and make them run like crap. well, maybe not crap, but lean running engines tend to idle rougher, and taking off from a stop, they seem to lack responsiveness to a small degree, and when cruising, the oxy sensor, which is always correcting the mixture, creates a barely noticeable, rythmic surging, which i hate. the oxy system is just an accessory on 80-83 911s, and they run smoother without it. the frequency valve still must function, but the sensor can stay unplugged.

have a look at this
http://www.auto-amd.com/kstar.asp

That is about US$1200 for "fuel and timing mapping for Porsche 911 SC"

How do they plan on mapping timing on a mechanical advance distributor?

Tom

h iTom....as to 'planning on mapping timing' .......they've been there done that........ read the stuff on the website or email them for the full spec....i've read reviews on this it's so impressive i'm getting one soonish......

John,

at which rpm should the timing be measured for the 35° advance you suggest, and should the vacuum lines remain connected?

regards

LeRoux

I can't find anything on how they do it on that web page, or the manufacturer's page. The SC distributor has centrifigal weights for mechanical advance, and vac canisters for advance and retard. I think the total advance/retard from the vac is 5°.

Unless they are using the limited adv/retard from the vac system, I would think converting the system to something "mappable" would be a lot of work.

I sent them an e-mail, we will see what they say.

Tom

hi Tom.....did you go here?
http://www.milfordmicros.co.uk/home/default.asp........
i'll see if i can find the Porsche and 911 world article for you and scan it.......

hi Tom.....did you go here?

i'll see if i can find the Porsche and 911 world article for you and scan it.......

hi Tom.....did you go here?
http://www.milfordmicros.co.uk
i'll see if i can find the Porsche and 911 world article for you and scan it.......

Yeah, they don't say how it works. All they say is that the stock system has no provision for mapping the timing, and their system does.

Tom

use a timing light with a dial in advance setting. set the dial to 35°. that will send the Z1 notch on the pulley way to the right at idle. raise the RPM until the notch on the pulley will move no farther to the left. that's total advance. turn the distributor until the Z1 notch lines up with the mark on the fan housing at total advance. most cars run well there, without pinging. if you notice pinging, retard a bit until it stops. do it with the hoses on.

I did exactly what JW has just described and my motor runs much better then it ever did (since I swapped it for my 2.7). I have a disconnected vacuum advance (ran crappy with it). The motor pulls very strongly with not evidence of pinging. I run 92 octane gas, but even with 89 octane I did not hear any pinging. There are a few guys on this board that I know of who run with the 35 total advance. All report good response and driveability.

JW set the timing and mixture in my car, just as he described above. Runs like an F-16.

WHAT DOES PINGING SOUND LIKE? I have been running like this for about 10 days and it is sweet. I am afraid that there may be pinging, but I don't know it. I have also heard that pinging can make your pistons look like a it's been pecked like a woodpecker pecks wood.

Also, the Z1 is about 15 degrees BTDC at idle. I have disconnected the vacuum advance completely.

It does not matter where the mark is at idle, if you are timing your engine this way. Pinging sounds like little gnomes inside your engine will ball pein hammers. Tink. Tink. Tink.

a tin can full of marbles on acceleration. you've heard rice cars on acceleration haven't you? just like that.

Thanks guys. Just to be sure, because I don't want to trash my engine. How loud is the pinging sound? Will I be able to hear it while driving my targa with the windows down and top off?

The only different sound I have noticed is a pop-pop-pop when I take my foot off the gas. That's a cool sound.