351w Electrical Question

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Jun 17, 2007 | 08:42 PM

stangfan78

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351w Electrical Question

I am in the process of swapping a 351w from a 85 Bronco into a 80 F100 that had a 302. I pulled the 351 this weekend and noticed 3 or 4 pigtails coming off the engine. My 302 only had one coming off the distributor. Anyone know what the other pigtails are for? I checked my Chilton manual but it wasn't much help.

Jun 17, 2007 | 08:53 PM

Franklin2

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From: Virginia

The 351w probably had a computer system. You can verify this by looking for a vacuum line connection on the distributor. If there is no vacuum line to the dist, then it's not going to work for you, and you need to buy another dist for a 351w from and older vehicle. You will probably have to get one from a car, since most of the late 70's early 80's truck 351's were 351m's. I am sure there was a non-computer 351w in some year truck, but I don't know what year it would be.

You are probably going to need a new carb too.

P.S. The 302 dist will not fit the 351w, the oil pump shaft is smaller on a 302.

Jun 17, 2007 | 08:56 PM

stangfan78

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The distributor does have the vacuum line.

Jun 17, 2007 | 09:14 PM

Franklin2

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This is what the 1980 should look like. If the 351w has the same wires going to the dist, it should plug right in, since it does have a vacuum advance.

Jun 17, 2007 | 09:16 PM

stangfan78

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What should be done with the other pigtails? Do you have a diagram for a 85?

Jun 18, 2007 | 07:18 PM

stangfan78

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After a closer look at the pigtails it appears that the others are for the ignition coil and gauges. Looking at the Chilton manual it shows the 85 Bronco had a ECC. Does anyone know if this was for all engine options or just the 302? I want to make sure I don't need a ECC to put in the 351, I don't see a connection for it.

Jun 18, 2007 | 11:00 PM

Franklin2

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With the eec, it did all the timing functions. So the eec dist had no advance weights or vacuum advance. All it had was a sensor for the timing.

Since your dist has a vacuum advance, you should be ok on that part. Did someone swap it at some time? I don't know. Do you have any mysterious wires coming out of the carb? The eec system also controlled the carb and had a tps sensor on the carb.