Duraspark retarding during startup
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
The one of mine that works has no numbers, brand, or any identifying marks that I can find. The one that doesn't work say Motorcraft.
Tuned
Joined: Oct 2008
Posts: 387
Likes: 2
From: Las Cruces NM
Didn't some of these trucks have a dual source (full & ported) vacuum advance? If so, could that play into the differences?
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
I don't think so. The retard function we are talking about is only at startup when there's essentially no or little vacuum. And it's only function was to ease starting by reducing the timing so the load on the starter was reduced.
I think the retard function via the vacuum advance was for emissions reduction, although that's just my understanding and I don't have a source for that.
I think the retard function via the vacuum advance was for emissions reduction, although that's just my understanding and I don't have a source for that.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
The answer is................ it works! Having said that, Jim's approach works more definitively. 
With Big Blue idling at 590-600 RPM I pulled the start wire (red/light blue) off of the starter relay and put it to the battery. The idle RPM dropped 40ish RPM to 550-560 RPM on my digital tuneup tach. And the timing retarded ~4 degrees. The RPM drop was enough to detect, so this is a really easy way to test the DS-II box. But the timing change was easy to see - though still not dramatic.
Then I changed over to the other DS-II box, the one marked Motorcraft in the previous pictures, and started the truck up. But, the kick-back was quite significant, so when I pulled the start wire and took it to the battery I was surprised that the idle dropped and the timing retarded exactly the same as with the other box. And, on subsequent restarts it started fine. So, the retard feature is there on the Motorcraft box, but it doesn't always work. In fact, when I was running that box it didn't work more often than it did work. But, since I went to the no-name box I've not had a single problem starting.
Bottom Line: You can easily test your DS-II box for retarding the timing during starting. Just pull the red/light blue wire and put it to the battery's positive post. If you hear a slight drop in RPM it is working. And if you aren't sure put a timing light on it.
With Big Blue idling at 590-600 RPM I pulled the start wire (red/light blue) off of the starter relay and put it to the battery. The idle RPM dropped 40ish RPM to 550-560 RPM on my digital tuneup tach. And the timing retarded ~4 degrees. The RPM drop was enough to detect, so this is a really easy way to test the DS-II box. But the timing change was easy to see - though still not dramatic.
Then I changed over to the other DS-II box, the one marked Motorcraft in the previous pictures, and started the truck up. But, the kick-back was quite significant, so when I pulled the start wire and took it to the battery I was surprised that the idle dropped and the timing retarded exactly the same as with the other box. And, on subsequent restarts it started fine. So, the retard feature is there on the Motorcraft box, but it doesn't always work. In fact, when I was running that box it didn't work more often than it did work. But, since I went to the no-name box I've not had a single problem starting.
Bottom Line: You can easily test your DS-II box for retarding the timing during starting. Just pull the red/light blue wire and put it to the battery's positive post. If you hear a slight drop in RPM it is working. And if you aren't sure put a timing light on it.
Thread
Thread Starter
Forum
Replies
Last Post
hackneyed1
1987 - 1996 F150 & Larger F-Series Trucks
13
Apr 10, 2018 03:50 PM
ladelld33
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
20
May 8, 2015 08:43 AM
gearhead351
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
5
May 18, 2007 03:16 PM
abelmoreno
1987 - 1996 F150 & Larger F-Series Trucks
5
Feb 19, 2004 05:00 AM
