Timing
Racer
Joined: Aug 2010
Posts: 337
Likes: 6
St. Jude Donor '16
My '81 with manual transmission is 6 degrees at 700RPM...Be sure to follow the shop manual instructions ( there are several steps to get the timing correct because of the computer controlled carb )...Good Luck!
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,328
From: At my Bar drinking and wrenching in Lafayette Colorado
There shouldn't be much "opinion" on setting timing an the '81 ECM-controlled car. Timing is set to 6 with the ECM wire to the distributor disconnected. Once completed, hook the wire back up. The ECM takes care of timing from that point on.
As a note, the ECM does not "know" where the initial timing has been set. It just assumes that it's working off a 6-degree baseline, and it advances timing from that point per the programmed advance profile. It will retard the timing if the knock sensor goes off. For higher altitude applications, you can gain a slight benefit from advancing the initial timing 2 degrees to about 8, and the ECM will then run the entire advance curve 2 degrees advanced. This is unlike the "modern" systems using a cam or crank sensor, which allows the ECM to actually "know" what the timing is.
Lars
As a note, the ECM does not "know" where the initial timing has been set. It just assumes that it's working off a 6-degree baseline, and it advances timing from that point per the programmed advance profile. It will retard the timing if the knock sensor goes off. For higher altitude applications, you can gain a slight benefit from advancing the initial timing 2 degrees to about 8, and the ECM will then run the entire advance curve 2 degrees advanced. This is unlike the "modern" systems using a cam or crank sensor, which allows the ECM to actually "know" what the timing is.
Lars
