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#347072 - 06/16/09 03:32 PM Re: 440 fuel mileage... [Re: minivan]
bordin34 Offline
super stock

Registered: 10/07/06
Posts: 842
Loc: Urbana, MD
My 73 400 gets absolutely terrible mileage. In my 73 Charger with 2.45 rear gears i get around 6mpg if I am lucky and driving normally. The only problem I have is the previous owner cross-threaded one jet in the primary metering block, could that be my problem?
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#347073 - 06/16/09 10:21 PM Re: 440 fuel mileage... [Re: bordin34]
SomeCarGuy Online   content
master

Registered: 02/02/03
Posts: 8205
Loc: Someplace you aren't
If you are getting only 6, it could have multiple problems. We need details to be able to tell you much. What have you checked or changed?

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#347074 - 06/17/09 05:09 AM Re: 440 fuel mileage...
Pale_Roader Offline
master

Registered: 01/21/05
Posts: 4135
Loc: the frozen wastes...
Quote:


First of all, your (I'll refrain from added descriptors I'd love to add) Caddy doesn't weigh any 6000 lbs unless it's a hearse




Well you nailed it. 68 M&M hearse to be exact, and i know exactly how much my car weighs. Its no lightweight. Had it down to just 5500 once with the interior gutted to sheetmetal and the bench seat.



Quote:

74 Dodge 4x4, yanked the 360 2bbl and installed a 440, essentially the combo would be equiv to stock 440 magnum. It would STILL kick your Caddy's ass, and got nearly 14 with the gearing in the p.u. in 2x4 and hubs kicked out




I'll take that race. I said it was slower than the Charger, but its pretty damn fast for three tons and highway gears. I'd put it up against any stockish 6000lb rig that isn't a diesel. I bet your trucks got a lot better gearing than my deathmobile.

I know we're not allowed to admit other makes are fast on Moparts, but i think the guys on a Caddy forum would take issue with your comment. Caddy's are kinda like Buicks... the math is just different.

All in good fun, huh...???

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#347075 - 06/17/09 05:23 AM Re: 440 fuel mileage... [Re: DaytonaTurbo]
Pale_Roader Offline
master

Registered: 01/21/05
Posts: 4135
Loc: the frozen wastes...
Quote:


Good job ignoring the fact that your 76 440 has a whopping 7.5:1 of factory compression ratio. Compression = efficiency and anything out of the late 60's would have had a CR in the 9's most likely. Then you take a smogger 440 and add a bit of cam to it, well you didn't have much cylinder pressure to start with any any cam over a stock passenger car/lo-po cam will drag down mpg.




Not ignoring anything here. I know this thing aint the best factory design (kinda my point), but the OP's car aint pushing much past 9 either. The engine i ran before this one was a 67, with the stock "10:1" and it was a pig too. It wasn't as nice an engine as the current one, but the CR made up for it. Both got about the same mileage in this car. I guess what i'm saying is that the OP has a factory set-up, which is hardly what i'd consider an efficient engine design (sorry Mopar gods...). If you were to go through the trouble to install a 500 Caddy behind the 727 in the same car (uh oh... blasphemy!) just to prove a point, i guarantee you'd see a dramatic improvement in MPG and power... despite the obvious cid increase.

Quote:

The exhaust he has is fine for his app.




I disagree.

Quote:

No way it is causing that low of a MPG.




I agree. I didn't say it was CAUSING the problem. He asked what he could do to improve MPG. Replacing it with an optimized system certainly would.

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#347076 - 06/17/09 07:42 AM Re: 440 fuel mileage... [Re: Pale_Roader]
SomeCarGuy Online   content
master

Registered: 02/02/03
Posts: 8205
Loc: Someplace you aren't
The mufflers he has on there flow plenty, the bends should be mandrel with that system, and have a H pipe. That is plenty enough, and not a hinderance to MPG.

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#347077 - 06/17/09 08:07 AM Re: 440 fuel mileage... [Re: SomeCarGuy]
bobby66 Online   content
master

Registered: 07/11/04
Posts: 2896
Loc: Arlington, Texas
When you check the timing, are you disconnecting the vacuum advance? More initial would help, with total between 34-38.
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#347078 - 06/17/09 02:55 PM Re: 440 fuel mileage... [Re: minivan]
Mr.Yuck Offline
Too Many Posts

Registered: 01/21/03
Posts: 24221
Loc: Brookeville, Md
who cares...why did you use a 440 if you want mpg's? the 2 don't mix. That said you should be doing better than 7mpg. I had a S/C'd 440 coronet w/ 3.91's and managed 11-12mpg at 70-75 mph
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#347079 - 06/17/09 03:25 PM Re: 440 fuel mileage... [Re: Mr.Yuck]
Anonymous
Unregistered


Honestly it should be about double what you're getting if that's highway miles.

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#347080 - 06/17/09 03:34 PM Re: 440 fuel mileage... [Re: Mr.Yuck]
Bill MeLater Offline
mopar

Registered: 11/12/08
Posts: 669
Loc: Wisconsin USA
Quote:

who cares...why did you use a 440 if you want mpg's? the 2 don't mix. That said you should be doing better than 7mpg. I had a S/C'd 440 coronet w/ 3.91's and managed 11-12mpg at 70-75 mph


EXACTLY: Figure around $30.00 a day for a reasonable ride at todays gas prices. The alternative is my '96 Dakota 2.5....I try to use that only for work. Enjoy...

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#347081 - 06/17/09 03:59 PM Re: 440 fuel mileage... [Re: Bill MeLater]
DaytonaTurbo Offline


Registered: 02/26/03
Posts: 20441
Loc: Manitoba, Canada
Reminds me of the 20 mpg 440 thread from a couple years ago...

http://board.moparts.org/ubbthreads/show...rt=all&vc=1

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#347082 - 06/17/09 07:04 PM Re: 440 fuel mileage... [Re: DaytonaTurbo]
SomeCarGuy Online   content
master

Registered: 02/02/03
Posts: 8205
Loc: Someplace you aren't
You guys that "don't care", don't drive much.

If he gets the MPG up to at least 12, he almost cuts his fuel bill in half, leaving more money for extra drives or improving the car in some way, or you name it.

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#347083 - 06/17/09 09:37 PM Re: 440 fuel mileage... [Re: SomeCarGuy]
minivan Offline
master

Registered: 01/13/04
Posts: 9066
Loc: Eugene, Oregon
Quote:

You guys that "don't care", don't drive much.

If he gets the MPG up to at least 12, he almost cuts his fuel bill in half, leaving more money for extra drives or improving the car in some way, or you name it.




Now were talking..

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#347084 - 06/17/09 09:43 PM Re: 440 fuel mileage... [Re: minivan]
Doc Fiberglass Offline


Registered: 07/04/08
Posts: 17475
GOOD ring-seal ... reasonable rpms ...and a nice safe lean air/fuel mixture = very decent MPG.

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#347085 - 06/17/09 09:55 PM Re: 440 fuel mileage... [Re: Doc Fiberglass]
SomeCarGuy Online   content
master

Registered: 02/02/03
Posts: 8205
Loc: Someplace you aren't
Have you checked anything else yet?

That cam not being degreed in is a real problem IMO. You can spend a ton of time chasing things and never find anything wrong.

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#347086 - 06/17/09 10:02 PM Re: 440 fuel mileage... [Re: SomeCarGuy]
minivan Offline
master

Registered: 01/13/04
Posts: 9066
Loc: Eugene, Oregon
I have the cap and rotor out of the distributor and was goin to install the light springs and a bit stumped on the mechanical advance limiters supplied with the pertronix dist. ( see my other thread).. Was/am going to take it to my mechanic guru friday..

Made a score today at the Junkyard for the correct AFB carb base for my dual snorkel air cleaner. Was using an AVS base with an adapter.. keeping the AVS base "just in case"...

So by not degreeing the cam and just setting it to the timing chain marks means that cam timing can be off?? thanks

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#347087 - 06/17/09 11:03 PM Re: 440 fuel mileage... [Re: minivan]
Lefty Offline
master

Registered: 09/05/05
Posts: 6515
Loc: Santa Cruz, California
Check the timing. My 440 picked up power and economy when I bought a new Pertronix plug and play dist. I checked the curve with a dial back timing light and it matched the recommended curve in this Mopar Action tech question. I think adding the vacuum advance helped the fuel economy the most.

http://www.moparaction.com/Tech/quest/SLOW_CURVE.html
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#347088 - 06/17/09 11:06 PM Re: 440 fuel mileage... [Re: Lefty]
Lefty Offline
master

Registered: 09/05/05
Posts: 6515
Loc: Santa Cruz, California
Quote:

( see my other thread)




I just realized I replied the same in the other thread, didn't know it was you with two similar questions...
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#347089 - 06/17/09 11:38 PM Re: 440 fuel mileage... [Re: minivan]
SomeCarGuy Online   content
master

Registered: 02/02/03
Posts: 8205
Loc: Someplace you aren't
It isn't likely to be off w/o a degree job, but you wouldn't be the first or even one of a few that has had a cam that was off enough to cost a lot of power. Of course if that is the case PG cn suffer...

I wouldn't sweat the degree deal at this point, it just makes this that much harder to figure out. That is why I always post to do the check while it is apart. Rules that out right off the bat.

The timing tab not being dead on with the balancer mark could have you off from what you are seeing on the light as well.

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