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Carberator change

I need to know if I can change a carberator on a 1974 Dodge 440 Winabego from 4 barrel to 2 barrel and what parts I need. I had been told all I need is a high rise manifold adapter (made by Holly?). I really need some help with this. When the vehicle was given to me it came with a new 2 barrel carb (in the box) so I assume I can change it out. Trying to save money so any help would be greatly appreciated…Thanks in advance.

You’ll want to make sure the 2 bbl is right for your 440. As for adapters, you might check out the Edlebrock web site, and give them a call. But why switch? You’ll gain little or no fuel economy and will likely lose power, something most RVs lack to begin with.

Also-if the current carb is bad, I think you’ll be better off getting a correct 4-bbl replacement rather than trying to save money with a 2-bbl

Yes you can, you need an adapter to do that, you might find one at JC Whitney. If you can’t find an adapter, a local machine shop should be able to make one for you.

Why would you want to do this? A 440 needs a 4 barrel to feed it enough fuel and air to move this Winnabego. A 2 barrel will not only reduce your power, it will reduce your fuel mileage as well. A 4 barrel is a two stage carburetor, it has two primary barrels and two secondary barrels, The secondaries only open when needed, otherwise the engine runs on the primaries only.

If you look down the barrels of the primary barrels, these will be the smaller pair, you will see that they are actually smaller than the two barrels of the 2 barrel carburetor. The two barrel carburetor uses larger barrels to compromise between mileage and power. With a 4 barrel, there is less compromise. The smaller primaries cause a higher airflow through the venturies, atomizing the fuel better. When the throttle is more than 75% open and the manifold vacuum is above 3"mg, the secondaries will open and allow more fuel and air in to boost the horsepower.

You will save more money just keeping the 4 barrel.

I also discourage the change to a 2bbl. If you are set on repairing this house/vehicle (perhaps it is your house) try and stick with fixing the orginal design. It may take some time for you to understand why things were designed as they were but it is better taking this time than becomming the engineer yourself.Typically the carb used on these 440’s had what is known as a power valve. If you have never operated a vehicle with a ruptured power valve it would make you think the carb is so messed up it must be replaced, but all it needs is the power valve.

It this is a recreational vehicle and not living quarters, don’t put a dime into it.

Do not change the 4bbl to a 2bll carb. You will actually use more fuel because of the engine size. You will be wasting money instead of saving it. I’ve been in the RV business for 40 years and this type of swap never works out. A good mechanic can rebuild this carb if it needs it or swap it out for a newer one.

The swap might work out but success is rare. That Rube Goldberg fella is usually in one of the boxes. But when the carburetor is off look down into the intake and inspect the EGR ports. They are prone to burn through and causes some big problems that are blamed on the carburetor.

If the engine has a vacuum controlled EGR the ports will not be under the carburetor. I checked an old Motors manual and it indicates that Dodge trucks with the 440 engine phased out the orifice in 1974. But I believe that the Winnebago engines continued to have the earlier system for quite some time. I recall many Dodge powered motorhomes showing up with burned out orifices.

My vote is for leaving it alone. When running a 4 barrel carburetor the back barrels, or secondaries, do not open anyway unless you have your foot in it so a 4 is essentially a 2 barrel anyway.

In the past, I’ve gotten into playing around with things like this (2 to 4, 4 to 2 conversions, adapter plates, etc) and things most often did not change much it at all. Matter of fact, with one particular Chevy I was wrestling with a conversion from the 2 barrel carb and manifold to a Quadrajet and 4 barrel intake dramatically improved the fuel mileage but that was a mutant.

If that beast is having fuel mileage problems maybe an inspection of the ignition timing and advance mechanism to make sure that it’s working propery would help a bit.
It’s not like a motor home is going to be a gas miser anyway; especially with a 440 behind it.

Let’s try and come up with something that would use more gas than a '74 motorhome with a big block…I got nuttin. There’s lots of work that’s probably needed on this ‘classic’, such as brakes, tires, overall tuneup, etc, etc, etc. Trying to come up with a better fuel system is waaaaay down the list.

I ask,why link your reply to mine?

Look at the timestamp in the upper right corner. I was not linking to your response on purpose. You were the last reply. That’s how the system works. Whoops! Sorry oldschool…I stopped using the “Post Your Reply” button a long time ago. I like to read all the other comments before commenting on my own. I’ll use the correct button from now on. Learning means we’re still living.

You won’t save enough or save any. There is also a chance that you will use more fuel when you drive in town with the two barrel carburetor.

I’ve owned 3 Chrysler built cars over the years with big blocks in them (pair of 383s and a 413 all with 4 barrels) and around 15 or a tiny bit more was about the best MPG that could be gotten on the highway. This was with cars, not vastly larger, heavier, and non-aero motorhomes.

Granted, the motorhome motors use a completely different camshaft profile but they will always suck the gas up pretty rapidly.
Tune it up, air the tires up, tweak the timing a bit, and try to minimize the damage at the pump.

When I use the “reply” I am making direct reference to that post,when I have an idea not related at all to what anyone else has said it is “Post your Reply”.

bac017479, do you have a frequent need for an RV? Unless you really want an RV, you’ll be money ahead selling it now, before you sink a bunch of money into an old money pit like this. Rent one when you need one.

Your going to want to stay with a 4 barrel. :slight_smile: