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Old 03-20-2015, 12:06 AM   #15
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Lets see 50,000#'s divided by 650 is 76.92 so I should be getting better than 8 mpg. Right?
In actuality I got 7.1 over a 3000 mile trip.

I expected 20 mpg!!

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Old 03-20-2015, 06:28 AM   #16
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Well, it's a rule of thumb, D, not a formula. I guess it skews a bit at the heavy end.

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Old 03-20-2015, 06:36 AM   #17
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Had a 460 in an RV several years ago. 7 MPG was what I saw when I checked in occasionally.

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Old 03-20-2015, 08:42 AM   #18
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Originally Posted by Handyhiker View Post
Sorry to ask such a goofy question. The wife and I are looking at a 1989 33 foot class A with a Ford 460. What fuel milage is average for a rig like this? I am guessing about 9. Am I close?
here's a professional opinion... and yes for free..so put your own value here..

I would steer away from a coach with a ford 460...they have a bad head design which is prone to manifold leaks/broken bolts / and busted heads...

the problem is so bad we refuse to work on them at our shop..

they depleted the head supply and for a time all you could get if replacement motors

the egr system is an other time bomb...

there are so many of these with exhaust leaks that the old timmers just can't hear

I'm batting 1000 on finding the leaks and broke off in the head manifold bolts so far....
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Old 03-20-2015, 05:28 PM   #19
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89 is that carb engine or fuel injected that early, if she's a carb engine count on 5-6, and definitely the manifolds will crack if they aren't already, a function of gas engine running the living **** out of its self up a long hill climb, at the top those manifolds are glowing read hot and don't cool evenly and crack or pop the studs.

one reason I try to get people to consider DP's but to each his own.

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Old 03-22-2015, 04:25 PM   #20
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My first Motorhome was a 29' class C Ford with the throttle body injection. Best mileage 6.5 to 7. 7 was with a strong tail wind. Cracked exh manifolds are to be expected. This engine really generates a lot of heat is why. Also either the #7 or 8 cylinder (don't remember which one) has a tendency to run lean and is hard on it's spark plug. Headers ( buy good quality and don't skimp) extra cool air ducts are a must. I also used to add a product called Water Wetter to the radiator. Helps keep the coolant Temps down.


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