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1981 D150 ‘Slant Six to 440 Swap’

SpilledSoup

SpilledSoup

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Hey, so I have a 1981 d150 with original /6. Picked up a 1978 440 out of a Winnebago. My tranny (original) is the 727 so I’m not concerned there (although I did get the 727 out of the Winnebago too).

My questions for anyone who knows or has done this, (this is my first full swap project) but what exactly do I need for the swap? Aside from mounts.

I’ve read through a pile of stuff across the web and everyone seems to have different opinions. Some say the original /6 rad works fine (I’m not sure I believe that - as it’s quite small). Just looking for an update on some things I need to get me hands on as i want to do this swap this winter.

1. What is needed for the swap? Flywheel? Rad? Mounts? Oil pan?

2. What’s a decent carb to run with a stock 440 setup? (I am not tuning it to crazy powerhouse - keeping it fairly stock with maybe new manifold/headers).

Thanks in advance.

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Oil pan needs to be a rear sump. Truck motor mounts will be needed. A long tail shaft 727 will be needed. Do not know what the tranny from the Winnie was short or long. Some /6 used 3 core radiator's, but I doubt if the inlet and outlets will match. Guess you did not get the carb with the 440?
 
The carb I would recommend is the Edelbrock 1406, yes it's only 600 cfm, but electric choke and quite simple. The guy's over on FCBO that have 70's Mopars that came with 440's and thermoquads all swear by them. Enough carb for a stock 440.
Clean looking truck
 
It's not an easy swap... or an inexpensive one... but it can be done. You may want to consider getting all the parts you'll need BEFORE tearing your truck apart though.

An area of concern to me is with the engine itself. Low RV miles do not always bode well for an engine. If the RV wasn't started regularly (typical)... you can easily have issues with internal components. Also... the 440 in a Winnebago was cammed for torque to haul that great lumbering box of wood and water up and down mountains... so you'll need to install a more modest camshaft or learn to live with low engine torque. You're probably looking at breaking the engine down for an inspection and possible rebuild anyway... but you should treat the engine as what it is... a 40+ year old hunk of iron that spent most of it's days sitting outdoors not running and not being serviced.

I believe the 727 transmission in the Winne is a short tail and the transmission behind a /6 is a long tail... but that point is mute. The /6 is based on the small block LA bolt pattern so that transmission, torque converter, and flywheel WILL NOT bolt up to the big block 440. You MUST use a transmission from a big block. On the other hand... since both of the transmissions you have are 727s, the output shafts and tail housings are interchangeable... so you should be able to make the Winne transmission work by combining them.

Besides the rubber engine mounts, you will need the adapters for a big block pickup that go between rubber engine mount and metal frame mount. Back in the day there was some ingenious fella who combined the rubber mount and the adapter into one unit... but the mounts you probably got from the Winne are sure NOT to have the adapter built into them... and the adapters by themselves can only be found on a BB truck or made yourself. There is no OEM or aftermarket source for them that I'm aware of.

Chrysler sometimes put a 3 core in /6 trucks when their stock of 2 cores ran low, but that was out of necessity and generally only on AC equipped models. The Winne 440 uses a 3 core (or perhaps 4 core depending on the RV's size) and... if memory serves me correctly... it's inlet and outlet holes are in the wrong locations. The /6 rad will work... barely. But for how long will depend mostly on it's condition, where you drive, what accessories you have, and how heavy your foot is. I think it better just to replace it with a BB radiator. No sense in finding out on the side of the road that you should have installed a 4 core instead... especially when dealing with Canadian winters. You will also need a new radiator fan and shroud... or go electric which makes it's own set of problems.

You'll need a big block oil pan and the oil pickup to fit the new frame... some/most/all of the accessory brackets on the front of the engine... a new exhaust system forward of the muffler. You'll also need a complete engine wiring harness for the 440 (including the engine module and ballast resister on the firewall). You MIGHT be able to splice in the engine harness from the Winne... but you'd better have a GOOD set of wiring diagrams for your 81 on hand.

Next you'll need to change some components in the steering/suspension system. It's been 30 years so I can't remember everything I did back then... but I do remember the springs and shocks are not able to handle the increased weight of the 440. A small block LA might be okay... but a big block? Absolutely no way I'm climbing into that deathtrap. If you do not replace them... the front of your truck WILL bottom out and any good sized pothole will likely cause you to go out of control.

Finally... some aftermarket parts are available, but MoPar no longer stocks any of the items you're going to need. Hopefully you have a donor truck with all those parts still on it for you to raid... but without that you're looking at many MANY days/weeks/months/years scrounging junk yards and overpriced eBay/Craigslist postings to find that one little part you absolutely have to have. That... or many nights fabricating those parts yourself.

Good luck to you and please post LOTS of pictures of your project.
 
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Well there's much to disagree with in that last post. The swap is a bolt in and it doesn't get easier than that. Yes you need motor mounts and frame brackets and they are available avertmarket, you need a truck oil pan and I'm not sure if that's available aftermarket but I'm thinking it is. I'd look for a big block radiator all the accessories on the 440 should work along with the kickdown linkage. The talk about springs and shocks is bunk, just replace as needed. Transmission depends upon what's under the truck now and what's under the motor home. Like I said this is a bolt in and the hardest part is going to be rounding up the parts.
I can help with the motor mount brackets and oil pan and pick up, I have them used and new. I believe that I have a set of NOS Hooker headers for a 2 wd 440 truck also. I will make you a smoke'n deal. It's a fun project go for it.
One more thing you don't need to change the wiring harness to go from the /6 to a 440, that's nuck'n futs. Lol
 
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Rusty Junk said:
The swap is a bolt in and it doesn't get easier than that. Yes you need motor mounts and frame brackets and they are available avertmarket, you need a truck oil pan and I'm not sure if that's available aftermarket but I'm thinking it is. I'd look for a big block radiator all the accessories on the 440 should work along with the kickdown linkage. The talk about springs and shocks is bunk, just replace as needed. Transmission depends upon what's under the truck now and what's under the motor home. Like I said this is a bolt in and the hardest part is going to be rounding up the parts. I can help with the motor mount brackets and oil pan and pick up, I have them used and new. I believe that I have a set of NOS Hooker headers for a 2 wd 440 truck also. I will make you a smoke'n deal. It's a fun project go for it. One more thing you don't need to change the wiring harness to go from the /6 to a 440, that's nuck'n futs. Lol
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The 170/225 slant 6 is an G/RG engine and the 273/318/340/360 are A/LA engines... both of which use the small block bolt pattern. The 383/400 are B-series engines and the 413/426/440 are RB engines... both of which use the big block bolt pattern. The two transmission bolt patterns are ABSOLUTELY NOT interchangeable with one another... therefore this project is NOT a bolt in UNLESS you use the engine, transmission, torque converter and flywheel from the Winne TOGETHER... which is exactly what I said. But then again he can't use that combination in it's current configuration because the output shaft on the big block transmission is too short, requiring him to modify the transmission... also what I said.

The 440 B/RB engine (which is what he got from the Winne) weighs ~760 lbs in long block form; and the 225 /6 (which is what he has in the 1981) comes in at ~430 lbs in long block form. Like what I said about the radiator... it could work... but just BARELY. I mean think about it... do 1/2 tons and a 3/4 tons have the same spring/shock ratings? It's all about carrying the extra weight. So you can trust your life to a /6 suspension holding an extra 300+ pounds of cast iron slamming down on that little rubber bumper ever time you go over a pothole... hoping you can control the bump-steer that sure to come with it if you want. Me??? I think I'll put the higher rated springs and shocks under the front end and keep driving... thank you very much.

If you know of an aftermarket engine mount/frame adapter bracket... please post the link here. I haven't found anyone selling them.
 
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Unwad ur panties and calm down nobody's gonna put a slant transmission on a 440.
I was thinking length because of driveshaft. Lol
 
Rusty Junk said:
Unwad ur panties and calm down nobody's gonna put a slant transmission on a 440.
I was thinking length because of driveshaft. Lol
Click to expand...

Actually nobody CAN bolt a /6 transmission behind a 440. It simply isn't possible. The transmission guts are the same, but the main body housings are completely different. The output shaft and the tail housing, on the other hand, ARE interchangeable... so all he needs to do is swap those parts and wah-lah... he has a long tail big block 727.

As for "unwadding my panties"... I'll have to ask my wife where they are. :confused::smuggrin:
 
1SykRyd said:
Actually nobody CAN bolt a /6 transmissiomayn behind a 440. It simply isn't possible. The transmission guts are the same, but the main body housings are completely different. The output shaft and the tail housing, on the other hand, ARE interchangeable... so all he needs to do is swap those parts and wah-lah... he has a long tail big block 727.

As for "unwadding my panties"... I'll have to ask my wife where they are. :confused::smuggrin:
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Tail shaft may or may not interchange. All depends upon the years being used. Housings are the same.
 
7mopar said:
Tail shaft may or may not interchange. All depends upon the years being used. Housings are the same.
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Yeah... you're right. I hadn't considered that. I am aware there may be differences in angles of the internal splines (it changed a couple times), but the angle you're thinking of is the spline that the front planet slides onto... and the closeness in years of the two transmissions means the likelihood is good they would be interchangeable. Still... he might just as well have a shop build it for him. The transmission will need to be disassembled in order to change out the shaft anyway, so it's pretty close to the same amount of work.
 
One thing the OP doesn't say is what type of motor home it is, if it's a van body the oil pan is the one he would need and I can't remember for sure but the brackets and mounts are the same as the pickup. So he needs to clarify what motorhome this 440 is coming out of. Moroso makes pans and there's used pans on ebay for the same price. Champion makes radiators but then again if it's the van body motorhome there's the rad.
 
Rusty Junk said:
One thing the OP doesn't say is what type of motor home it is, if it's a van body the oil pan is the one he would need and I can't remember for sure but the brackets and mounts are the same as the pickup.
Click to expand...

You know... I stand corrected. I was thinking the Class A Winne this whole time and I completely forgot all about the Minnie Winnie. And they did have long tail 727s... so they would be a direct bolt-in.
 
Van uses a center sump just like B bodies. He will need a rear sump. If the engine is from a Winne it quite possible it has the proper mounts and sump. All Winne's used a straight axle and I would guess a rear sump pan.
 
Like I've said I have enough parts to do two more swaps and then some scraps. I'm only going to hold on to the parts for one, my own.
 
I’m doing similar swap, ‘78 D150 w/ S6 to MH 440 and using an A833 trans. Bouchillion has a kit with mounts, rear sump oil pan and pickup. https://www.bouchillonperformance.com/pdc_big_block_truck_install_kit

If you have large diameter brake booster, it will have to be changed to small diameter booster or manual brakes. Large diameter booster hits valve cover. My S6 radiator is way to small for cooling a big block engine. The water pump inlet on my 440 engine is on drivers side, something to look at as many stock radiators had inlet on passenger side
 
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