timing advance

[928 Bro]

Guyz I been reading passed post on timing advance and for my US 1980 928 seems like a sweet spot is 28 degree at 3000 rpm with vacuum hose removed and plugged. Now I see the 10 and 23 degree mark but 28 degree is not there. How far is 28 degree from 23 if I was to make a mark?

[19psi]

There are no degree marks so it's a wild ass guess if you're eyeballing it.

I just bought a new digital timing light from Advance Auto which takes out all the guess work.
There is a display on the gun and you set the timing that you want down to the 10th.
Set your timing light to 28º and then rev the engine to 3000 rpm (yes the gun also displays RPM!!) and aim the light. Adjust your distributor so that your timing is at the 0º TDC hash mark and you'll be exactly at 28º.

I was at 22º and pushed mine to 25º and the difference is VERY noticeable. 28º sounds high...make sure you're not pinging.

The name of the light is Actron and I bought it through Advance Auto, part # CP7529. I placed the order online for pickup at my local branch. Price was $104.99. I applied a coupon code for $40 off any order over $100 which brought the total down to $64.99 + tax.

For the price I love it considering it also has a tach built in which is mandatory on a 928. My old Sunpro was useless on the 928 as it would turn off when the engine revved over 1800 rpm and I'd just be guessing at anything past the 23º mark.

[XLR8928]

I run mine at 10deg BTDC at idle, which is roughly the equivalent to the euro 28deg setting. I run 89 octane with no problems.
-Kerry

[928 Bro]

As we advance the timing should we lower the octane. I'm running premium should I run mid grade. Thanks for response

[19psi]

No, you increase octane to stop pinging that may occur.
A 1980 US spec should run fine on 87 octane. If you set your timing to 28º and get pinging, try 89. If it pings with 89, it's time to back off the timing. Go overboard and you'll end up hammering your pistons to death.

[928 Bro]

OK thanks