Hey from Michigan

[Tbswick]

Northville Michigan here. Owner of a 1981 Ranger f350 XLT dually

[Gary Lewis]

Welcome!  

1981 - Good year.  Is it a 400?

And, a dually.  Or, as Ford would say it, DRW.  Just learned yesterday that yours will have a narrower bed than those from '85 on.  Bill/85lebaront2 educated me on the axle lengths for the DRW's.

Anyway, post up some pics!

Oh, and do you want to be on the member's map?  I usually add the first name of the member.

[Tbswick]

It is a 400/C6. Less then 45,000 miles on it. Kinda rough right now but I’ll slowly get her back on the road after 20+ years. Needs brakes but run like a kitten.

[Gary Lewis]

The 400 is my favorite engine.  It is an underdog and is much maligned.  But, it has slightly larger stroke than a 460, so can have stump-pulling torque.  And it has very large ports, much larger than those of the Windsor series, although smaller than the 460's.  Plus, it is lighter and smaller than a 460.

Tim Meyer has all sorts of goodies for the 400, including pistons and oil system upgrades, so you can make it whatever you want.

[Tbswick]

I’ve never had a 400 but I did drive a 351M in a 1978  Diamond Jubilee edition T-bird back in the early 90’s.
Not sure if I’m leaving it stock or putting heads off a 351C 2V, 4 bbl intake and the autolite 4100 carb I own. That’s if I don’t sell the 351C 1st.
I’m help my sister inlaw sell a bunch of dually ford truck and tons of parts. The 81 is my payment for helping the. I’ve post a add in the sale section here. Real clean truck but needs work. I just don’t have the time as of right now. Still  inventorying what parts and truck we need to sell. He owned 7 in total. I took the 81, brother inlaw is keeping the 86. We sold 2 89’s for far. Still have a 85,88 and a 95 to sell. If your looking for parts let me know.

[Gary Lewis]

Hope I didn't hurt your feelings with my post in that thread.  Didn't realize it is your advert.  But, now you know my thoughts on trucks - if they run and I can drive them to check them out then I'll pay a lot more than one that I can't check out.  I've done that several times and have gotten burned each and every time.  So now I don't buy a non-driver to fix up, only to part out.

On the 335 Series, the 351M is the little brother to the 400.  Same engine save for the crank and pistons.  Unfortunately you can't get pistons that will give you anything less than 8:1 compression, if that, for the 351M.  But you can for the 400 - via Tim Meyer.  So I bought a 400 for $40 and put the crank in Dad's 351M and now have a strong 400 - it put out 400 HP and 500 ft-lbs at low RPM on Tim's dyno.  

A friend of mine has an '81 F250 w/a 400 and he recently replaced the timing set with an aftermarket one, which corrected the 4 degree retard from the factor.  And he installed an Edelbrock intake and carb.  Said it doubled the power of the engine.  I seriously doubt that - especially since another friend put an aftermarket timing set on his 351M and it helped but didn't make a huge difference.  However, apparently the combo of timing set and 4bbl carb made a big difference on the 400.

However, if I remember correctly 351C 2V and 351M/400 heads are the same.  I have a write-up here (Engines/351M/400), and there's a link in it to Bubba's pages where you can check out the head spec's to prove that.  If I'm right, then there's no reason to pull the heads off the 351C.

[Tbswick]

No hard feeling lol. If it doesn’t sell the way it sits I’m sure we will just part it out. Honestly it would be a shame to part this truck out in my opinion but we need get rid of it some how. I just can’t sell it for what other people think it worth. The way I’m looking at it this, I’m selling a brand new 460 long block with tons of other new parts. It just happens that those new parts come wrapped in a 1985 F350.

I’ve been reading that by putting this 351C heads on my 400 will bump the compression up from 8:1 to 9:1. I’m not looking to make tons of HP or anything. Just want a little more peep. I would be happy with 300HP or close.  I forget but as for now it’s rated at like 160-180 HP. I’m not putting headers or anything like that on it. I wanna keep that stock look. That’s why I would use stock parts like a 4bbl intake from the 351C “I have 2” and the autolite 4100 carb. When you open the hood I want it to look like it was born there. Definitely putting a new timing chain in it and maybe “maybe” A tiny bit bigger cam.

[Gary Lewis]

I don't know what you are reading nor where, but the M-block "bible" is Bubba's site, and here's an excerpt from that page:

You might even wonder, “Since the 351C and M-block share the same cylinder head design, couldn’t I improve my M-block’s performance by swapping in a higher compression (smaller chamber) 351C cylinder head?”

Unfortunately, the answer is, “Maybe.”

The 351C 2V heads have essentially the same size ports and the same size valves as the M-block heads, so they would be compatible with the runners in an M-block intake manifold, but the combustion chamber size difference will not produce a significant change in the M-block compression ratio, and in some cases, the 351C 2V cylinder heads actually have larger chambers than M-block heads!

The 351C 4V CobraJet heads and later 351C 4V heads have combustion chamber volumes close enough to M-block chamber volumes that they are not worth swapping to significantly increase the compression ratio. The only 351C 4V heads with small enough chambers to make a significant change in compression ratio are the early 351C 4V heads or the rare Boss 351 heads. However, the main disadvantage of using the big port, big valve 351C 4V heads on an M-block is that the power band of the M-block is not compatible with the port volume of the 351C 4V heads. The 351C 4V heads do not achieve optimal airflow velocity until engine speed reaches about 3500 rpm, and M-blocks in a typical (i.e., truck or large car) application really need to produce a lot of torque and power below that speed. To realize the true benefits of the 351C 4V heads, you’d have to rev your engine up to 6000 rpm (or higher) routinely.

And further down that page he has a pair of tables that give the combustion chamber volumes for the 351C and then the M-block heads.  So you can figure out what you have and then see if the swap will help.  And I don't think it will, so I'd check it out before you try it.

As for power ratings, the 1982 dealer's facts organizer gives:

                Horsepower      Torque
302:         132 @ 3400    232 @ 1800
351W LD  139 @ 3200    279 @ 1400
351W HD  157 @ 3400    271 @ 2400
400          153 @ 3200    296 @ 1600
460 (van)  212 @ 4000   339 @ 2400