Ignition question: '77 F250

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Aug 30, 2004 | 12:23 PM

Troy77+79

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From: North Carolina

Ignition question: '77 F250

Hi Everybody,
First, I just want to say that this site is awesome!
I cleared up a bunch of questions I've had in the past couple of weeks just reading through the archived posts.
I am very grateful to the creators of the site and the thousands of people who freely give their time to answer questions and also make it a very fun place to be.

Now, my question:
My Dad and I are currently swapping engines in a '77 F250. We've already pulled out the 400 V8 that was in the truck and have put in a 351M that we took out of a '75 LTD. We still have a bunch of stuff to do before we'll be anywhere close to starting the truck, but I have a question about the ignition system that I’d like to get resolved.
The electronic ignition box on the truck has a blue grommet but the car has a brown (I think) grommet. What should I do? Should I try to use the box from the car? I asked a friend and he said I should swap distributors (use the 400 dist. on the 351M) and keep using the blue grommet box that came with the truck. Another question, are the distributors interchangeable? My friend didn't know but I'm sure someone on here does.

Thanks in advance,
Troy

Aug 30, 2004 | 01:23 PM

73Custom

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From: SD

Your friend is right, swap the 400 dist into the 351 and use the blue grommet box. The blue ones are cheaper/easier for replacement and keeping the one the truck was made with will make future work easier...

Marty

Aug 30, 2004 | 02:18 PM

Franklin2

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From: Virginia

You can swap the distributors, but I am not sure there is really any difference in the distributors themselves. Look at the wiring coming out of both. If they have the same color and number of wires, I would say they are the same, and only the brown box has the different features. I would think the blue box would work with either if the wires are the same.

It's up to you, the distribtutors will swap. Just make sure you get it back in right.

Aug 30, 2004 | 10:17 PM

Troy77+79

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From: North Carolina

Hi Guys,
Thanks for the quick response. I'm not sure but I believe the dist. that's on the 351 has one wire more than the one that came on the 400. I'll try to check tomorrow evening or Wednesday and post back. I'll probably need some tips on changing the dist. out, as I've never done it before and I'm a little nervous.

Thanks Again,
Troy

Aug 30, 2004 | 11:05 PM

Dealford

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From: Belleville, Ontario

Clean around the 351 distributor area so no debris will fall in during the swap.
Scribe a line on the dist. body & the engine to mark it's position. Take the cap off & mark the position of the rotor. When you pull the dist. out, the rotor will turn. Mark this position as well. Transcribe the marks carefully onto the 400 dist. & set up for installation. Turn both dist's. upside down and compare the hexagon shaped hole that the oil pump drive goes in. You may need to turn the oil pump drive shaft a little. Install the 400 dizzy.
While the dizzy is out, DO NOT turn the engine over or you will have to reset to #1 etc.,etc.
AL.

Sep 1, 2004 | 02:34 PM

Troy77+79

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From: North Carolina

Well, I had a chance to check the wires leading to the distributors and there's no difference between the 400 or the 351. Both have 3 wires, 1 orange, 1 black, one grayish light colored wire. All three are in the same order as well. Franklin2 said he thought if the wiring coming out of the distributors was the same that the blue box should work with either dist. Does anyone know for sure? I'd rather not have to change them if I don't have to. I've got plenty of other things to do on this beast.

Thanks Guys,
Troy

Sep 1, 2004 | 07:37 PM

Franklin2

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From: Virginia

I just went to partsamerica.com. I plugged in a 75 ltd with 351m, and pretended I wanted a new distributor. Two numbers that came up were:

302873 dual vacuum electronic dist

302893 single vacuum electronic dist

I then plugged in a 1975 f250 with a 400. I looked up the distributors they called for inthis application, and the above numbers came up. So if you went to the parts store, they are going to give you the same dist for the car or the truck.

I wasn't totally positive, but now I am that they are the same.