I bought a 1985 F250 custom a month ago with an awsome body and interior. I found out quick that the motor is worn with little oil pressure and 230,000 miles. Its a 351 windsor HO ,a C6 auto and a non full floater rear end. I started looking on craigslist for a motor and found a 81 15 passenger van with a 351 windsor and c6 auto and full floater rear end with 96,000 miles for $600. I noticed right away the heads are different as the truck has large plugs and the van has small plugs. the van also has air pump ports in the back of each head. I know the HO came with a different cam and 4 barrel carb to accuire the 210 hp. But obviously the heads are different too. If I put this motor in my truck should I use my HO heads and change the cam and intake? I really hate to take this factory assambled motor apart but I dont plan on running the air pump. I heard in my younger years that not running the air pump will burn valves.

Also I'd like to know if the full floater rear end is a direct bold on replacement in my non floater truck. Any info on any of this is greatly appreciated. Its been years since I played with old fords. I'm really enjoying getting back into this but I just can't remember all this stuff. LOL.

 

I have a suspicion the van engine is not original, or the heads are not original. It should have the small tapered seat plugs, not the larger ones with the washer. I am assuming that's what you are talking about.

Don't worry about the "HO" hype. The 4 barrel gave most of the increase, with the cam playing a possible small part, but not enough to worry about it. I would stick the van engine in there complete. You can plug those ports, running without the pump will not hurt a thing.

I am not sure about the rearend though.

 

If it's an E-250 or E-350, the rearend will swap fine.

If it's a E-100 or E-150, (I doubt it because it's a 15 passenger van) then it has a 5 bolt lug pattern.

And just for completions sake. The Custom Trim level was dropped for the 1982 through 1986 models, and it didn't come back untill 1987. So if it has the word custom on it, it was swapped into it from a 1980 or 1981.

The Custom was Ford's customizeable trimline during the 70's and 1980-1981, and could be ordered any way you wanted within reason. There are a few very highly optioned Customs out there. When the name was dropped in 1982, Ford went to a policy of option restrictions and you had to buy a XL or XLT Lariat to get certain options that was avaliable on the Custom just a year before. This angered some buyers (including my father) and is why the Custom came back in 1987, but it was dropped again later in the 90's.

Hope this helps.

 

The van is a 15 passenger e350. Franklin2, the plugs are like you said in the van. small tapered seat plugs. My truck has the large plugs. Is there any difference in heads as far as compression or valve size to make it worth switching?

 

Your truck should have the small plugs also. Someone may have swapped heads or engines. I think it was around 70's heads that used the big plugs.

 

All heads after 1978 were the same on the 351w and the 302, except the 351w heads had larger holes for the larger head bolts.

It was in 78 they went to the large chamber heads. I believe it was sometime in 85 or 86 they started changing the heads a little bit. 86 has the small chambered heads people don't like, but I believe the trucks kept the same large chambered heads. After that I lose track, but they made changes here and there, and the mustang guys keep track of this closely. They need the high rpm flow, we need the low rpm torque in a truck, so our priorites are a little bit different.

 

Well i noticed when I removed the valve covers the other day that the rocker arms are like an aluminum alloy like material and are on studs instaed of pedastals. The rocker arm nuts bottom out on the smooth part of the stud where the threads stop. I'm not real familiar with 289/302s. I'm used to the 351m/400 and 460 engines. These heads have me stumped now wondering what they are. Older style valve covers that say "Power By Ford" are on the heads too. Typical 70s not 85. Is there a book or online reference to casting numbers I can acess? wondering about the motor in the truck now. What could it be?