* This post was edited 04/29/08 01:45pm by eyeteeth *
If you switch from a big block (i.e., a 440 cu. in.) to a small block (i.e., a 318, 340, or 360 cu. in.), you will need to change transmissions. The innards are the same but the tranny cases are different for small block and big block engines. (Not a big hurdles as A727 trannies for small blocks are still fairly common but the ones for the big blocks are becoming rare.)
Avoid the A518 overdrive tranny ... you're much, much better off with an A727 and a Gear Vendors Over/Underdrive unit if you want overdrive capability.
A lot of the motorhomes had a 4.56 ratio in the rear axle ... a 4.10 ratio would probably work just fine for you and would boost the mileage some. (Mine has a 4.10 ratio and I'm happy with it. My other motorhome has a 413 cu. in. big block and 4.56 rear axle ratio ... that one's definitely set up for towing a trailer or a toad.)
Ask Leeann what ratio she's got in hers.
1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A
I've got a 440/727 on a 20' chassis and we average about 9 mpg.
However, I also have a '90 B250 van with 360 and A-518 with 4.10 gears and I average 11 mpg (and Griff's right: stay as far away from the A-518 as you can...it's nothing but a PITA) - and that's loaded or unloaded, towing or not.
Here's the thing about the 440: I have plenty of power in the hills, towing or not. With the 360, the B250 struggles in the hills and the mileage drops to about 10. I had a 19' Class C with a 360 in it briefly and it had no guts whatsoever - it could hardly get out of its own way. And that was unloaded and not towing.
Personally, I think the 1-2 mpg difference is worth keeping the 440.
'73 Concord 20' Class A w/Dodge 440 - see profile for photo
You could probably get much the same effect, for far less money and time by swapping gears, and changing the carbonation.
That's what I'm hoping, and planning at some point in the relatively near future.
![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/biggrin.gif "biggrin")
A larger, more powerful engine will yield you better fuel economy because it doesn't have to work as hard.
The 360 in my 1/2 W150 was only 8mpg un-loaded. If I had a 440 in there (everything else being equal), I'd be in the 12-14mpg range, an improvement of 1.75 times.
I find it humorous that we're willing to spend thousands of dollars to perfume a pig! That is, try to get better mileage out of a HOUSE!
That same $5000.00 or whatever for an OD system is still 10,667 miles of driving if you don't do a thing. Money better spent is quality tires properly inflated, a fresh tune-up (with engine tweaking to maximize it's performance), free-flowing exhaust, free-flowing air cleaner, and a really good front-end alignment.
Just my 2 cents.
She ain't purdy, but at least she's slow!
Leeann wrote:
I do hope you meant carburetion, not carbonaton
I do hope you meant carburetion, not carbonaton
Maybe... maybe not.
![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/tongue.gif "tongue")
While these engines aren't power-houses, they are very reliable, readily available in running form from scrap yards, retrofit easily into everyday vehicles, and people with trucks like 2500 series Suburbans are getting about 30mpg with them...
I am curious how they would work in something like my 20' C class. Lord knows with a 360 2V, she ain't fast as it is, I doubt the little 4 banger oil burner can't be much slower, but certainly better torque (which is more important than horsepower anyway).
Set it up right, and you can burn vegetable oil in it in a pinch! Or McDonalds waste oil...
"Food" for thought!