timing specs for a 1983 US 911SC

[zje]

I am trying to set the timing on a US 1983 911SC. I have the factory manual and am not sure if I should use the specs for the 1987, 1980, or 1981 model. I'm guessing since it's a US car it would be 1980?

Thanks!

[hotaru]

It depends on your engine type, see below (from 1983 SC tech specs book):







stan

[Flat6pac]

Got one in the garage presently.
5 degrees BTDC @ 950 rpm
Vacuum hoses removed and plugged.
Oxygen sensor disconnected.
The hose with vacuum at idle goes to the connector closest to the distributor.
Bruce

[emcon5]

911 SC timing specs per the Bentley manual are:

78-79, 5º ±2º BTDC@ 950 RPM, vacuum hose connected, with max advance 26º ±2º BTDC @6000rpm, vacuum hose disconnected

80-83. 5º ±2º BTDC@ 950 RPM, vacuum hose disconnected, with max advance 21º ±2º BTDC @6000rpm, vacuum hose disconnected

For best performance, some folks advocate leaving everything hooked up and setting it so full advance is 35º, and not worry about the timing at idle, let it end up wherever it happens to end up. If it pings, back if off a couple degrees.

If you need to pass a smog check and that is something they look at, you may need to adjust as necessary.

Tom

[zje]

Sorry, realized I should've been most specific, I was looking for ignition timing, but all of this information was extremely helpful. Based on the chassis number, it appears I have the 930/16 engine type. Interestingly enough, the chassis stamp has "ZZZ" in it, the serial number starts with a 16 (this is a Targa).

I have the bentley and was unsure of whether or not the 78-79 also applied to all US models, it appears I should treat the 83 US version as 80-83.

Thanks so much!

[tirwin]

Originally Posted by emcon5

911 SC timing specs per the Bentley manual are:

78-79, 5º ±2º BTDC@ 950 RPM, vacuum hose connected, with max advance 26º ±2º BTDC @6000rpm, vacuum hose disconnected

80-83. 5º ±2º BTDC@ 950 RPM, vacuum hose disconnected, with max advance 21º ±2º BTDC @6000rpm, vacuum hose disconnected

For best performance, some folks advocate leaving everything hooked up and setting it so full advance is 35º, and not worry about the timing at idle, let it end up wherever it happens to end up. If it pings, back if off a couple degrees.

If you need to pass a smog check and that is something they look at, you may need to adjust as necessary.

Tom

The late CIS cars were de-tuned from the factory to comply with emissions regulations. You can get back some performance that was left on the table BUT I wouldn't attempt to do this unless I was confident in the overall maintenance.

Caveats:

1) you need to run the highest octane gas available, and preferably non-ethanol.
2) need to make sure the dizzy is in good working order and the vacuum enrichment is working properly
3) I'd set base idle mixture to be slightly rich
4) rest of the fuel injection system needs to be in proper working order - no vac leaks, fuel pressures in spec, good injector spray, etc.