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I have recently fallen in love with the look of the 69 - 70 Eldorados. I can only imagine the power of thr 500 must be impressive. Can anyone tell me what the typical gas mileage is with that engine? When I was a teenager, my parents bought a new '69 Calais which had the 472 but in those days no one cared about MPG too much and I don't recall what that car got.
 

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Not positive about the 69-70, but I have a 71 which gets about 13 on the highway and 9 in the city...and 4 gallons to the mile in a parade.
 

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It seems, in my experience, that miles per gallon is not the best way to describe fuel consumption. But rather, minutes per gallon. If you compare the minutes it takes to burn up a gallon of gas on the highway, you'll see some similarity to the minutes per gallon in city driving.
 

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I drove back from Iowa with my '68 and got about 15 or so... the secondaries were stuck though i think haha. I havent driven her in some time so i cant give you a recent calculation.
 

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So about 9 around town is average for a mid '70s 500? and about 14-15 highway is normal?
 

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1970 Sedan deVille hardtop
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I doubt you'll see 13.5 around town unless you are being towed...
15 highway is realistic however. I see 15-16 in pure highway driving with the cruise on and ~12 in mixed driving (roughly 50/50) in my '70 SDV.
Just be sure to give it a proper tune up, keep the tire pressure up, and don't drive like a maniac (all the time)
When setting the idle, be sure to do the factory-prescribed lean-drop idle setting. That will make a difference in mileage. Switching the vacuum advance to full-time, full-manifold vacuum will help you around town also, but I'd change the vac cannister to a unit that gives less total advance, or an adjustable one. If you have the vac advance like this, you've gotta remember to disconnect and plug it when setting timing.
Also, buy a dwell meter, you'll need it to properly tune up the points distributor. Always reset the base timing after changing the dwell.

Oh, yeah, and if you want a 500 under the hood, don't get a '69 - they "only" had a 472, but at least it's a high-compression motor.
 

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steinec said:
I get about 8mpg around town with my '70 500...:ill:
Hey just think, some guys get like 11-13 mpg with their brand new 4x4's with small V8's in them.
 

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I~LUV~Caddys8792 said:
Hey just think, some guys get like 11-13 mpg with their brand new 4x4's with small V8's in them.
Our '05 Excursion gets a solid 12-14 highway with a v10 6.8L. Its got some power though.
 

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JTraik said:
Our '05 Excursion gets a solid 12-14 highway with a v10 6.8L. Its got some power though.
Whats the city MPG? I dont mean anything bad by this, but I'm curious :)
 

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The Ape Man said:
That's pretty solid!
Touche! Ok a solid 13. :rolleyes:

I~LUV~Caddys8792 said:
Whats the city MPG? I dont mean anything bad by this, but I'm curious :)
Im pretty sure it gets about 8 or better with pure city driving. I think its a very efficient engine considering, its 4x4 and weighs in at 7800 lbs. She can move too! Still think the diesel would have been better.

Another cool thing about these v10s is that when they overheat a few cylinders shut down and act as pumps, pumping cold air through the block somehow! Im no Ford guy but thats pretty neat... for all i know though, several vehicles probably have that feature.
 

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Like the Cadillac Northstar? The cylinder deactivtion (just deactivating the injectors, not the valves) was one of the big features when it was introduced. Supposed to allow you to run for some time with NO coolant!

How many gears does that excursion have? I know the automakers have been putting more than four gears in the automatics thesedays. That could explain the good mileage and acceleration.
 

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:gun: :gun2: :gungrin: MEGA THREAD HIJACK!!!
Dont know jack about the northstar!

The gas Excursions run a 4spd. and the diesel runs a 5spd.

Gear Ratios 4-sp-------5-sp
I------------2.71:1-----3.09:1
II-----------1.54:1-----2.20:1
III----------1.00:1-----1.54:1
IV----------0.71:1-----1.00:1
V-----------------------0.71:1

Final Drive Ratios 3.73:1,4.10:1,4.30:1

MEGA THREAD HIJACK!!! :gun: :gun2: :gungrin:
 

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The 6.8L makes similar HP to a high compression 500, and less torque. Friend's F250 6.8 weighs in around 5400 or so, which isn't too far from my Deville. I bet I'd beat him if I ran duals... (and he didn't have 4.10s)
 

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it all depends on how people keep up their car..have oil changed done often and fluids up....my 425 gets about 10/11mpg city and highway does a hole lot better it jumps to like 18/19..maybe even more depending on condition of car..but the 500 is a gas guzzler i bet i could only imagine...
 

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Ok, with all this mileage talk I'm feelin pretty bad.
I have an 80 hearse, supposedly with the 368 (non-8-6-4).
The folks I bought it from said it had a 400 "something" in it, kids just don't remember anyting...
I'm lucky to get 10 mpg, it seems to be running fine, smooth, and lots of power.

What throws me about the possibility of the 368 being replaced (the emissions sticker says 6 liter) is that is has plastic valve covers, feedback carb, computer controlled distributor.
Is there any visual checks that I can make to be sure that is is indeed a 368? It sure seems to have a lot more power than is advertised for the 368.

Plans for the drivetrain in this car (let me know if I'm outa line anywhere in here.)
Dual exhaust, standard "old school" quadrajet, standard HEI, and a shift kit in the tranny (plus tranny cooler). All I want this car for is to tinker/make kinda nice, tow my 14' Shasta camping trailer (2000lbs), and for the looks I get driving down the road. So maybe even a #3 cam would be in order too... Not lookin to tear up the streets... LOL!

Anyway, thanks for the input ahead of time, and sorry about dredging up an old thread.
 
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