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Discussion Starter · #1 ·
Hey all,

My fiancee and I just bought a 27' 1984 Ford Fleetwood Jamboree Class C RV (E350 chassis) and plan to use it for a summer long road trip once we get married in May. We're so excited! This has been a dream for a long time.

I am stoked with everything about the RV...except the gas mileage. It has a Ford 460 in it, so we're learning that we'll be getting about 7 MPG tops.

With the amount of miles we plan to put on the Jamboree, I'm considering a diesel swap. Ideally, it looks like a Cummins 6bt is the way to go.

I saw @Joz 's thread about swapping a 6bt in a 1990 Winnebago 27' RV. It was so cool to see he accomplished it, and I felt inspired with my similarly built RV.

Frankly, my fiancee and I have very little automotive knowledge. We bought the RV at a great price and went forward with a "learn as we go" mentality. For me to do this swap on my own is next to impossible.

My question in short is, what would you recommend to someone like myself if I want to go ahead with the swap? I don't know exactly who to talk to, what to do, or where to look for parts. Any help would be incredibly appreciated. Anyone in my area (Kansas City, MO) or even within 300 miles that can help me do a swap?

I called a few different shops in Kansas City. No one I talked to was able to do a swap, but they offered some good advice. A few guys estimated that the swap would cost about 20k. I've seen some threads/videos of people doing swaps for less than 10k. Any insight on an accurate price would also be great. Sourcing my own donor truck/parts seems like the best way to keep costs low, but correct me if I'm wrong. As I mentioned, we won't be using it much until this summer, so we have a lot of time to line things up.

Thank you so much in advance for any help or advice you can offer to a couple whose dreams are too big for their own good. :) Excited to hear from you!

Ben
 

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Ben,

I love the "idea" of a 6bt in a 1984 E350 chassis RV. I took a 4bt out of a 1986 E350 bread truck and successfully stuffed it into a 1986 F150 pickup. My build thread:


Read down to post #4, that will save me a lot of typing.

Make note that I ran the engine in the donor for about a year, so I had confidence in the engine.

I see some obstacles:

1. Legal - Where you register the vehicle, do you have an annual smog emissions check? My truck is legally registered as a diesel vehicle in Cochise County, AZ (says diesel on the registration). This engine swap is not legal in some states and smog emission areas (for instance: Reno, NV).

2. Time - I don't think that you, or any mechanical shop, can have the RV roadworthy by May.

3. Reliability - About 15 years ago, my neighbor failed a Chevy 454 about 6 states away. That ate into his retirement cash reserve. He drove it successfully for a few years, then it sat for over 10 years. The fuel system totally gummed up and the engine did not want to start (TPI fuel injection, just can not run it off of a gas can).

Tire Land vehicle Wheel Vehicle Car

The folks that bought his property gave it away "Free - must be removed my Monday". This tow failed at the first slightest uphill grade.

4. A place to work - Do you have a heated shop?

Tire Wheel Vehicle Automotive tire Motor vehicle

5. Tools: How are you going to remove that 460? And how are you going to insert that 6bt? You just can not remove the hood and lift straight up...
p.s. I am 10 years older now...

6. Sound insulation - that 6bt is a LOT louder, and the doghouse probably will require modification.

7. Road testing - I highly recommend a few "shakedown test drives" - the object is to find and fix the problems before you head out on the big trip.

I've finished my coffee - I'll close with some alternative thoughts.

About 18 years ago, we had a 1971 IH Camper Special pickup (3/4 ton with a fresh 392 CID IH engine). We bought a very used small 5th wheel camper and set out on a month long vacation (roughly Tombstone,AZ to Port Angeles, WA in a big loop). I doubt if did much better than 7 MPG.

My worry (I'm 77 years old - worry comes with my territory) is that you will not have a reliable RV ready for your honeymoon.

The costs: $10K - $20K for a conversion, still will have to buy lot$$ of fuel, and diesel repairs are more expensive on the road.

Consider:

1. A few shake-down trips on this 1984 RV (you need to do this gas or diesel). First, get the fuel system clean of old fuel, (start with finding all the fuel filters - replace them - cut the old filters open and look for rust and trash).

2. Make your grand trip with the 460 gas motor. Bring the title, if the RV has a major failure, you can dump it and get home in a rental.

Russ
 

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OK. You are taking a good approach to the question. We have had several E350 swaps done on motorhomes on the forum. It would be a bit challenging for someone not really into automotive work. A 6bt like found in the Dodge trucks will fit but takes a bit of planning. A second option would be a 4bt which is a smaller version of the 6bt. Cost wise, the 6bt would probably be cheaper. One thing you need to do is look at cost. I was a cost accountant in a former life so that was my specialty. You need to look at your cost of operation for both your current engine and a diesel. You mentioned fuel economy and that is one aspect. Fuel prices vary depending on where you live or go. In my area, the local Walmart is about the cheapest. Regular gas is $2.75 and diesel is $3.35. Your gas E350 will get around 7 MPG as you mentioned and the diesel will probably get in the 16-18 MPG range if properly driven. You must consider regular maintenance items. Oil changes for the diesel will cost you about twice as much as the gas engine. The 460 gas will hold 6-7 quarts of oil where a 6bt holds 12 or more depending on the oil pan. The Ford FL-1A oil filter for the 460 costs $3.97 at Walmart and the diesel will cost you $10-16 depending on what brand or type you use. The diesel and gas fuel filter will be similar in price but the diesel one will get changed more often. Then there is the big cost of the swap itself. The $20K number you mentioned is not crazy high. You will be changing both the engine and the transmission. Most guys who do their own work figure in the neighborhood of $10K or better for a swap. If you honestly look at the numbers a diesel swap is not cost effective unless you plan on driving a couple hundred thousand miles. When I bought my first diesel pickup I calculated it would take me 100K miles to break even on the additional cost of the engine which was $4000 in 1986. And that was when diesel was $.60/gal cheaper than gas. Now it's $.60/gal higher. Now, if the 460 was on its last legs and needing replacement the swap might be more viable but a replacement gas engine is no where near as expensive as the diesel. I love diesels and every vehicle I've purchased since 1979 has been diesel. A total of 1 car to 2 trucks driven near 700K miles.
 

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Discussion Starter · #4 ·
@Russ McLean @char1355, you guys are great. Thank you for the genuine, honest, and insightful input. The more looking into this I've done in the past couple days, the more and more it seems like this probably isn't in the cards for my fiancee and I. Too much financially, too much to sort out to make it a smart option for us. We'll be driving a whole lot, but not nearly enough to break even in the next several years. I'm glad to have looked into this though! And grateful for your help and the countless forums filled with advice on here.

An option I'm looking into now is checking out what the 460 EFI Guys have to offer (460efiguys.com) to see if I can purchase something to supe up the 460 engine as much as possible, instead of going through the headache of a swap. I realize this is getting away from the main scope of 4BTSwaps, but if anyone has had any experience with their products/services, I'd love your input. If not, thanks again for your time and help!

Ben
 

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@Russ McLean @char1355, you guys are great...

An option I'm looking into now is checking out what the 460 EFI Guys have to offer (460efiguys.com) to see if I can purchase something to supe up the 460 engine as much as possible...
Thank you.

A quick look at rockauto.com confirms that the 1984 460 engine has a carb. A well thought out EFI installation will give you more reliable starts, somewhat better MPG and less trouble with altitude changes and vapor lock (why I no longer have large cubic inch IH engines). Be cautious with the "supe up " part - dramatic increases in horsepower tend to find the weakest link (connecting rods, transmission, U-joints, differentials, etc...). The idea is return under your own power...

Start with an absolutely clean fuel system - Remove your existing fuel tank and and clean it. If it has any rust, or large amount of trash deposits - seriously consider a new fuel tank.

Again, get the job done in time so have a few shake-down runs before departing on the grand trip.

Russ
 

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Hey Ben,

The 460 is a great motor. I don't think you will need any more power, if it is running correctly.

How many miles on the RV? Has it been sitting recently...or, has it been in more-or-less continuous use?

My inclination would be to address any been-sitting issues (e.g., old fuel, fluids, filters, hoses) and then run it some, as is.

FWIW, I have found the guys on FTE to be super helpful:


Roy
 

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Your 1984 460 should be 225 HP and 380 lb ft of torque. The engine originally had 365 HP and 485 lb ft when introduced so it lost a lot along the way due to detuning and smog controls. Fuel injection came along in 1988 and the engine had 245 HP and 400 lb ft of torque. I suspect the fuel injection models gained a bit of fuel mileage over the carb models but not by a whole bunch. Just a bit more power and better manners. With your motor home, you're pushing a cement block on wheels.
 

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Discussion Starter · #9 ·
Be cautious with the "supe up " part - dramatic increases in horsepower tend to find the weakest link (connecting rods, transmission, U-joints, differentials, etc...).
Today I learned that "supe up" does not equal the more general "tune up" hahaha. Sorry @Russ McLean. I should be more careful with how I phrase things. Thanks again for your help.

How many miles on the RV? Has it been sitting recently...or, has it been in more-or-less continuous use?
@irhunter, it has 39,000 miles. So very low for being 37ish years old now. Last time it was driven for a big trip was in August, when the guy I bought it from brought it to Kansas City from somewhere in Nebraska--about a 3 hour trip, and he said he had no issues at all. I've driven it a couple times since I bought it in early December, but just to pick up an RV cover and get it in the shop to get a big list of fixes/replacements taken care of: a fresh starter, alternator, new belts, batteries, hoses, front brake pads, wheel bearings, an oil change, and maybe* a new transmission (*I'm waiting to hear from them if they can do that for me officially). Basically getting it as much preliminary maintenance done on it as possible. I've checked out the forums over at FTE, those guys are indeed great.

Your 1984 460 should be 225 HP and 380 lb ft of torque. The engine originally had 365 HP and 485 lb ft when introduced so it lost a lot along the way due to detuning and smog controls.
@char1355, can you help me understand what you're saying? Sorry for my lack of knowledge. Are you meaning that my particular motor should be able to get back to 365 HP/485 lb ft? Will those help my fuel mileage? Undoubtedly, I agree that even with an extremely well-tuned engine, my 460 won't get the most amazing MPG because of the home attached to it hahaha. Thanks for your help!
 

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My take on it is if you want a diesel RV then do not convert an RV to diesel. Convert a diesel delivery truck/van into an RV. Those are built for hundreds of thousands of miles, unlike a typical RV. Look into the whole "vanlife" sub-coulture for build into and ideas. If you're not too deep into this RV then you can harvest it's various bits and systems for the conversion. If it's resale vale exceeds the components cost, then sell it after the conversion is done to re-cover funds. And in the mean time use it!

I have been around and driven two OEM 460EFI trucks, and know of a third. They all get about 10 mpg. I've been told that they get that pretty much regardless of how they're loaded.

With a Class C you're pushing more air, so it wouldn't surprise me if such an engine in your rig won't quite reach double digit mpg's. Speed won't be your friend. My own SOP is to stay off the super-slabs as much as possible anyway. That sure helps our fuel economy, when I manage to keep my foot out of it....

If it doesn't already have one, an over-drive might help with mpg's, but the pay-back will be very long term. I would expect to see an mpg gain in the lower gears due to being able to run a slightly deeper rear axle ratio to make it easier on the engine in those gears, than when actually in over-drive.
 

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I’m installing a 5.9 Cummins in a 1990 E350 Club wagon as well as converting to a NV4500 with a Gear Vendors Overdrive and a 4x4 swap too. I started a YouTube channel to highlight the build as I go. Attached is a link to the first video where I go over the install of the Cummins. Hope it’s helpful


Hood Automotive tire Motor vehicle Tire Automotive design
 

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I'm glad the record of my conversion is still helpful.
You would need a very special shop to agree to do a conversion of this magnitude.
I totally agree with Russ and others - you can spend a TON less to get that old 460 running well than messing with a conversion. And, much easier to get help on the road if needed.
Be smart about your modifications and you'll end up with a great rig. Just accept the cost of fuel and enjoy your trip.
 

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I’ve done a few unusual swaps over the years and had my share of 460s both carbed and injected. The earlier 460 got its power through cam timing and by Retarding the cam through the gear offset the NOx emissions were cut along with the power. If you plan to take an ‘84 on a trip, remember this: C6 reverse gear burns up under load. Using a 4x4 C6 transmission gives you an extra low range for pulling and there is a bolt on overdrive available.
I would use the higher compression 460 with propane which was cheaper than gas or diesel and doesn’t go bad like they do. 110 octane equivalent.
I did a 7.3L diesel swap in an E350 cube van and it sucked going E350 to E350. The overdrive factory automatic is a problem child.
Keep a spare correct starter with you. Replace all ujoints and pre-lube them. Double check all the fluid levels because there are those jealous people out there who are willing to ruin what you have and even lie to take it away from you.
I got waay offtrack. Clean the oil pan and make sure the roll pin in the distributor driven gear isn’t worn and about to snap due to oil back pressure or pan crud blocking the flow. There is aftermarket fuel setups that can be dialed for both power and economy.

Today I learned that "supe up" does not equal the more general "tune up" hahaha. Sorry @Russ McLean. I should be more careful with how I phrase things. Thanks again for your help.



@irhunter, it has 39,000 miles. So very low for being 37ish years old now. Last time it was driven for a big trip was in August, when the guy I bought it from brought it to Kansas City from somewhere in Nebraska--about a 3 hour trip, and he said he had no issues at all. I've driven it a couple times since I bought it in early December, but just to pick up an RV cover and get it in the shop to get a big list of fixes/replacements taken care of: a fresh starter, alternator, new belts, batteries, hoses, front brake pads, wheel bearings, an oil change, and maybe* a new transmission (*I'm waiting to hear from them if they can do that for me officially). Basically getting it as much preliminary maintenance done on it as possible. I've checked out the forums over at FTE, those guys are indeed great.



@char1355, can you help me understand what you're saying? Sorry for my lack of knowledge. Are you meaning that my particular motor should be able to get back to 365 HP/485 lb ft? Will those help my fuel mileage? Undoubtedly, I agree that even with an extremely well-tuned engine, my 460 won't get the most amazing MPG because of the home attached to it hahaha. Thanks for your help!
 

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Conversions aren't for rookies, as there's always issues.............mechanical, electrical etc. The previous advice shoud be heeded ! As you learn, start with a toy you don't have to depend on, and ease in to making it a daily driver .
 

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Discussion Starter · #15 ·
C6 reverse gear burns up under load. Using a 4x4 C6 transmission gives you an extra low range for pulling and there is a bolt on overdrive available.
I would use the higher compression 460 with propane which was cheaper than gas or diesel and doesn’t go bad like they do. 110 octane equivalent.
@Car buck, I'm so sorry, but I understand almost nothing you wrote here 😅 My automotive knowledge is very little. I'm sorry about that. What's the most relevant information for me here?
 
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