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KSagal · 08-09-2015, 07:03 PM

I finally took my 'new to me' 88 Fleetwood Southwind for a weekend trip to Maine. It was only a couple hundred miles round trip.

I got just under 5 mpg out of my 454, with this 34 foot class A. (Camper calls itself a 34 footer, but it is over 35 feet long, bumper to bumper) Seems a bit low for me, but I have no frame of reference. (trip was relatively level, no great increases or decreases in elevation)

My only other RV was an 85 class c, 28 foot, with a chevy 350. Going up into the mountains, I got about the same, but over 9 or 10 coming down, so averaged between 7 and 8.

Where do my numbers hit you as being what I should have expected, or what you get?

nothermark · 08-09-2015, 07:05 PM

Sounds a bit low but how heavy was your foot? ;-)

Piker · 08-09-2015, 07:09 PM

When I was growing up, dad had a 26' allegro with a carbureted 454... we got 6 mpg on average. I think our gross weight was around 12000.

-cheers

dennis45 · 08-09-2015, 07:12 PM

Quote:

Originally Posted by Piker

When I was growing up, dad had a 26' allegro with a carbureted 454... we got 6 mpg on average. I think our gross weight was around 12000.

-cheers

Hello Piker, How's that brand new Cummins working for you? Have you had a chance to burn off some Diesel this summer?

Piker · 08-09-2015, 07:24 PM

Quote:

Originally Posted by dennis45

Hello Piker, How's that brand new Cummins working for you? Have you had a chance to burn off some Diesel this summer?

I've snuck it up the hill in front of our house a handful of times, but other than that, no. I have a huge repair job on the siding I'm undertaking right now... gonna be probably another year before we're back on the road... maybe longer. I've been trying to blog the siding repairs here in the vintage section under the "New exterior siding" thread... but it's a pretty slow process. To be honest... rebuilding the cummins was more fun...

Cheers

KSagal · 08-09-2015, 07:27 PM

Quote:

Originally Posted by nothermark

Sounds a bit low but how heavy was your foot? ;-)

I was on it a little, but also have to do some carb adjustments. If I really stepped on it, it acted up, like it was choking or flooding. I could ease it faster and faster however.

This was a maiden voyage. I cruised at about 63. One time I came close to 70, but most of the way was between 63 and 65.

There were 6 tolls (3 up, 3 back) so I had some clear 0 to 60 opportunities, and these are where I felt the carb issues.

Also, I was burning some of the gas that was in the tank when I bought it. I do not know how old that gas is, so I must go thru a tank or two before I start to get too excited. Who knows what is in that tank. I don't even know how big it is. (I think 85 gal or so, but I had only put in 15 gal before the trip, and 30 after the trip, and never saw the gas gauge below 3/4.

Piker · 08-09-2015, 07:54 PM

If the gas was old... there could be a certain amount of varnish in the carb. Might pay to just tear it down and clean it up... Might solve all your problems?

What kind of carb is it? The old quadrajets were better on fuel than most of the aftermarket carbs because of the small primary and large secondary setup. They were finicky though as far as tuning goes. I had an old pickup with a 454 in it that I eventually had to swap out the quadrajet with an edlebrock cause of tuning issues... the edlebrock did fairly well... it may not have gotten the fuel economy of a properly tuned quadrajet, but it beat the pants off a poorly tuned one... and it was extremely easy to tune.

Cheers

KSagal · 08-09-2015, 08:09 PM

Quote:

Originally Posted by Piker

If the gas was old... there could be a certain amount of varnish in the carb. Might pay to just tear it down and clean it up... Might solve all your problems?

What kind of carb is it? The old quadrajets were better on fuel than most of the aftermarket carbs because of the small primary and large secondary setup. They were finicky though as far as tuning goes. I had an old pickup with a 454 in it that I eventually had to swap out the quadrajet with an edlebrock cause of tuning issues... the edlebrock did fairly well... it may not have gotten the fuel economy of a properly tuned quadrajet, but it beat the pants off a poorly tuned one... and it was extremely easy to tune.

Cheers

On that previous 350 I mentioned, I replaced the quadrajet with an edlebrock and it was a great improvement. But this one is not nearly as hinky.

I am thinking of loading up the tank with some detergent additives, but I still have lots of that old gas. (I am guessing it is old. I have had the unit since October, but it may have sat where it was before I bought for a few years. That might make the gas potentially as old as 5 years).

Piker · 08-09-2015, 08:17 PM

Might pay then to run this tank till it's down to almost empty, and add the fuel system cleaners then when they will be more concentrated? Otherwise you'll have to add quite a bit of cleaners to treat 85 gallons.

That carb and engine was also originally tuned to run fuel that didn't have ethanol in it...

Cheers

KSagal · 08-10-2015, 04:48 AM

Quote:

Originally Posted by Piker

Might pay then to run this tank till it's down to almost empty, and add the fuel system cleaners then when they will be more concentrated? Otherwise you'll have to add quite a bit of cleaners to treat 85 gallons.

That carb and engine was also originally tuned to run fuel that didn't have ethanol in it...

Cheers

Sounds like a "road trip"! is in order, for medicinal purposes! Since the last trip to Maine and back only brought me down to 3/4 tank, I may be out for a while... If I get this plan past the boss (DW), you will be my new hero!

Kidding aside, I agree. Among other things, most vehicles like to move, and don't get better just sitting in the barn. As I flush out the necessary projects from the 'would be nice' projects, my repair and maintenance needs will become more focused.

MH went to the CG without a big problem. I have a couple minor leaks to address in the plumbing (feed to toilet is weeping, white water, not black, whew!) and the 12 volt pump that worked fine at home and on my water hose at home, started to leak at the CG. I will take the head off to see if the gasket is bad, otherwise it is a new pump for me. It works well, but I cannot have that drip drip drip forever. (I did not check the pressure at the CG)

After that, I will get back on the engine and carb.

CJ7365 · 08-10-2015, 09:07 PM

Yeah I think under 5mpg, which is saying you got 4 MPG, is a bit low, if you haven't done it already, I would go ahead and change out the plugs, wires, cap and rotor, cant hurt, get that carb adjusted and put some fresh gas in there, I would expect at least 6 or 7MPG at 60MPH

Im only at 27' 12,000LBS, also TBI instead of carb, I average about 8, last trip out to Calif. one tank I got 9 all flat land.

Dtwallace · 08-10-2015, 09:42 PM

Quote:

Originally Posted by Piker

Might pay then to run this tank till it's down to almost empty, and add the fuel system cleaners then when they will be more concentrated? Otherwise you'll have to add quite a bit of cleaners to treat 85 gallons.

That carb and engine was also originally tuned to run fuel that didn't have ethanol in it...

Cheers

In theory thats a good idea, but I would be prepared to replace filters if that stuff just happened to break loose on the road.

If you are looking for a quick fix, then do it close to home, and go through the whole fuel system before taking a chance of getting stuck on the side of the road.

That 454 is a good engine, but there are things that can be done to make it run better for your application, like a change over to fuel injection system. But thats something for another thread.

MudDuck514 · 08-11-2015, 11:27 AM

Hi all,

Karl, glad to hear you had a successful "road trip" in you "new" motor home.

While I have yet to take mine on the road yet,beyond getting it inspected and moved into the RV Park we are living in, and therefore can't tell you what kind of mileage I am getting, I can say that about 10 years ago I had a 1979 Class "C" motor home with the Dodge 440, and got about 6 mpg on a trip from San Antonio to Lawton OK.

As for the Q-Jet, once you figure out how to work on them they are pretty good for power and economy - just need to know how to properly adjust the thing!

Mike and Melissa

Nick-B · 08-11-2015, 01:48 PM

Hi Karl,

Old fuel will definitely affect mileage. Keep burning that old stuff out.

You'll not likely to get much better than around 6 MPG. Between the carb, non-overdrive trans and 35+ feet of rolling brick, the odds are stacked against matching your old Class C mileage.

Another thing to check is the distributor advance weights. If they are sticky or rusty, clean them up. If you can find a shop (and experienced mechanic) that has a distributor curving machine they can optimize the advance weights and springs to better match the needs of a big motorhome.

The Q-Jet is a good carb but it is less about the "tuning" and more about fixing the leaks. The soft plugs in the metering wells all leak fuel (internally) and the top plate is often warped from overtightning the top bolts which results in a vacuum leak which prevents the metering rods from properly controlling fuel flow. Sometimes simple replacement is the best solution but then you'll have to play with tuning a generic replacement by experimenting with different jets. Good Luck!