Quick question on 351W
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 7,298
Likes: 45
From: Southern California
I have an '81 with a factory equipped 351w EEC-III engine. It is a California truck.
EEC-III distributors are easy to identify. The rotor has two electrodes and it fires alternately from both of them. The poles on the cap are also staggard in hight:
There is no reluctor or stator in the distributor because it uses a crankshaft position sensor or CPS. There is no vacuum or mechanical advance because the spark is controlled by the ECM and can provide up to 50° of advance.
Only one module is made for the EEC-III ignition. It has a brown grommet and five wires vs the DS-II ignition's six wires. BTW, the yellow grommet is for the high altitude DS-II variant.
One other important difference between a DS-II distributor and a DS-III distributor: The engine firing order is the same, but the order of the wires on the cap is totaly different. The reason the distributor cap is wired different from the actual firing order is because Dura Spark III distributor's fire alternately from both sides of the rotor. That's why the rotor has electrodes on both sides. (If you start from #1 and jump back and forth 180 degrees Counter Clock Wise you will see the normal firing order.)
351w firing order: CCW 1-3-7-2-6-5-4-8
351w wire order: CCW 1-5-7-8-6-3-4-2 (EEC-III/Dura Spark III distributors only.)
Now after viewing my photos, can you identify which ignition system you have? If you have an EEC-III engine, you are going to have to use the correct replacement parts to keep it working.
EEC-III distributors are easy to identify. The rotor has two electrodes and it fires alternately from both of them. The poles on the cap are also staggard in hight:
There is no reluctor or stator in the distributor because it uses a crankshaft position sensor or CPS. There is no vacuum or mechanical advance because the spark is controlled by the ECM and can provide up to 50° of advance.
Only one module is made for the EEC-III ignition. It has a brown grommet and five wires vs the DS-II ignition's six wires. BTW, the yellow grommet is for the high altitude DS-II variant.
One other important difference between a DS-II distributor and a DS-III distributor: The engine firing order is the same, but the order of the wires on the cap is totaly different. The reason the distributor cap is wired different from the actual firing order is because Dura Spark III distributor's fire alternately from both sides of the rotor. That's why the rotor has electrodes on both sides. (If you start from #1 and jump back and forth 180 degrees Counter Clock Wise you will see the normal firing order.)
351w firing order: CCW 1-3-7-2-6-5-4-8
351w wire order: CCW 1-5-7-8-6-3-4-2 (EEC-III/Dura Spark III distributors only.)
Now after viewing my photos, can you identify which ignition system you have? If you have an EEC-III engine, you are going to have to use the correct replacement parts to keep it working.
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Posting Guru
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From: Graham, WA
HorsePuller: That is exactly the setup that was in the truck when I bought it. After the truck started dying once it heated up I had a member of FTE come look at it and he is trying to show me how to switch from that setup to the blue grommet/vacuum advance dizzy. Is this possible?
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From: Niceville, FL.
If you have a Duraspark II distributor (the one with the pickup coil) and an Ig. Module with the blue grommet then just wire them color for color as I posted earlier for Duraspark II. Can't be all that difficult if you do one wire at a time. If you can't find the proper connectors just cut the connectors off, strip the insulation from the wire ends and twist the wire ends together using small wire nuts from any hardware store.
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Posting Guru
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From: Graham, WA
Originally Posted by Piffery1
If you have a Duraspark II distributor (the one with the pickup coil) and an Ig. Module with the blue grommet then just wire them color for color as I posted earlier for Duraspark II. Can't be all that difficult if you do one wire at a time. If you can't find the proper connectors just cut the connectors off, strip the insulation from the wire ends and twist the wire ends together using small wire nuts from any hardware store.
-Thank you
-John
Last edited by oneminizut; Apr 14, 2007 at 03:44 PM.
Posting Guru
Joined: Jun 2004
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From: Niceville, FL.
I have no idea about the shaft lengths. I had thought the Duraspark II distributor would be a drop in replacement for the EEC dist. Hopefully someone else can help you on that. Maybe you'd be better off posing that question in the Engine Forum that covers 351W's.
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 7,298
Likes: 45
From: Southern California
Yes, I believe the distributors are different length.
You will have a better conversion if you change carburators too. Because the ECM controls the Variable Venturi Carburator and it takes information from the Throttle Position Switch.
Everything now controlled by the ECM will have to be switched over to thermal/vacuum switches for best operation. Once you break the link in the chain of the ECM's operation by removing a componet it goes into a default mode with fixed outputs.
The solenoids for the air pump, EGR valve, evaporative emissions system, all that stuff and more.
You will have a better conversion if you change carburators too. Because the ECM controls the Variable Venturi Carburator and it takes information from the Throttle Position Switch.
Everything now controlled by the ECM will have to be switched over to thermal/vacuum switches for best operation. Once you break the link in the chain of the ECM's operation by removing a componet it goes into a default mode with fixed outputs.
The solenoids for the air pump, EGR valve, evaporative emissions system, all that stuff and more.
Last edited by horsepuller; Apr 14, 2007 at 06:08 PM.
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From: Graham, WA
Originally Posted by horsepuller
Okay, you are half way there then. See the edits I made to my last post.
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