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Mpg Wow!
https://slantsix.org/forum/viewtopic.php?t=31933		 Page 1 of 1
Author:  Valleyant [ Tue Oct 28, 2008 1:26 pm ]
Post subject:  Mpg Wow!
Hi,
I took the '72 Valiant on a 79 mile trip this morning. It was mixed driving about half city miles and half highway miles (70 MPH). It was the first time I had taken note of fuel usage. I filled up the tank before and after the trip ( gas was $2.19 a gallon :D ). I used 3.7 gallons. My brick of a car averaged just over 21 MPG. This is an entirely stock '72 with 225/904 and 2.76 gears. I have not converted to HEI (still points) nor recurved the disitributor and it still has the 1 3/4 " exhaust system so there is potential for better MPG. I do run synthetic fluids in the engine/trans and diff. I was so impressed I had to share...nico
Author:  MichaelS [ Tue Oct 28, 2008 2:04 pm ]
Post subject: 
MPG is good, but gas for 2.19 a gal, send some back to NY we are still at around 2.80.

Your car must be in good shape, that is some good mileage. My '74 never got that good and I have been driving it since it had 35,000 miles back in '84.
Author:  wjajr [ Tue Oct 28, 2008 2:29 pm ]
Post subject: 
One 260 mile round mile trip on secondary roads running 55-60 mph, the Dart got 21 and a butt with a 3.55:1 rear end. This was the only time I have checked fuel consumption.

My first 67' Dart during the early seventies, powered by a 273 V8, with three on the tree could at best get 16.5 mpg. That car I checked often during the first energy crunch with odd even gas station rationing. Ah those were the days.

To put this in perspective, the 300C AWD gets 23 mpg on the same trip, it is 1200 pounds heaver, and has 165 hp or so more.
Author:  steponmebbbboom [ Tue Oct 28, 2008 4:40 pm ]
Post subject: 
as a cautionary measure, pull your sparkplugs and make sure they are golden brown on the insulator, if they are clean or white you may be running lean. detonation is sometimes difficult to hear and will erode pistons and overheat valves. if all is well, enjoy it.
Author:  Chuck [ Sat Nov 01, 2008 2:10 pm ]
Post subject: 
Don't forget to use milage markers on the highway to check your odometer. I have seen a lot of A-body cars that read 10% high using radial tires. In fact, most of my cars read 10% high, including my '95 Chrysler. I have to subtract 10% from the milage on the odo to get a correct MPG figure.

When I went to 14" tires on my '63 Dart I changed the speedo gear in the trans.
Author:  Valleyant [ Mon Nov 03, 2008 9:53 am ]
Post subject:  Update
Thanks for all the input....Yup I was blessed to find a car in such good shape and low miles...it currently has 49,700 miles. When I first got it, it would smoke on start up but that was a few oil changes ago and that problem seems to have gone away and the fact that I am driving it on a regular basis is doing it good. I did check plugs and yes they were lighter than I would want...I was hearing detonation on the highway when I would accelerate and going up steep hills....I changed out the main jet from the original 53 to a new 59 today and was really amazed at how easy it was...if you are listening A-Ted. Getting the cork gasket to cooperate was the toughest part...I managed to find another gasket from a parts carburetor that was made of a different material to get it back together...took me 15 minutes though..LOL...Changing the jet seems to have smoothed the idle a bit more and the detonation seems to be gone now....torque seems to come in sooner and I am using less throttle to accelerate...and Chuck I checked my odometer and it was spot on with the mile markers on the expressway...I was happy to discover that....my car has 195/70-14 Insignia radial tires....Will do another mileage check real soon!.........Nico
Author:  THOR [ Mon Nov 03, 2008 10:06 am ]
Post subject: 
A 53 main jet????????? Holy cow that's lean! That's not a reman carb is it? I've been running a 56, and I get about 23 on the freeway in my Tuna-Boat Swinger, and it runs an all-out 19.35 in the quarter!

Gas here is still in the 2.3X range.

~THOR~
Author:  Valleyant [ Mon Nov 03, 2008 10:20 am ]
Post subject: 
I don't know if it was a reman...I bought it with the understanding it was a NOS carb....Gas is still about the same and even a little lower some places...I am going to the track before they close for the season and see how it does with open exhaust and this new jet change...hoping for low 17's............nico
Author:  THOR [ Mon Nov 03, 2008 11:33 am ]
Post subject: 
Stock motor and 1 barrel carb with single exhaust... you are looking at high 18s at best. This is from personal experience of driving slow cars... :twisted:


~THOR~
Author:  Valleyant [ Tue Nov 04, 2008 3:04 am ]
Post subject: 
Woah! tune-up those slow cars of yours because they are capable of better times :wink: . My last time out I had a best of 17.8 at just under 75 mph with my Valiant..stock 1 barrel with 904 and dinky 1 3/4 exhaust.....OK I did open the exhaust about a couple of feet from the exhaust manifold at the track.
I drove the car to work this evening and it feels like a different car, definately a step in the right direction. I'm still experimenting to find the right jet size, though, with the stock exhaust...will try going down "one" jet size at a time to find the optimum tune.............Thanks, Nico
Author:  Valleyant [ Thu Nov 20, 2008 11:34 am ]
Post subject: 
Hi,
I have settled on a 57 jet for the holley 1920. I still need to do a MPG check to see how much it has changed from the 53 jet that was in there originally. Cold engine driveability has been improved greatly. I can start it up, kick it off of high idle after about 20 seconds and drive off smoothly and with no hesitation. Before the jet change, I had to be careful with the amount of throttle I gave it UNTIL it warmed up, or else it wanted to stall. I prevented this by smoothly opening the throttle and most times pumping the gas pedal to keep 'er going. Now it takes on grades and as much throttle as I can give it without hesitation...almost feels fuel injected....okay, okay almost. Nico :)
Author:  footballhero_7 [ Thu Nov 20, 2008 3:42 pm ]
Post subject: 
Man 2.19 a gallon, the cheapest price for gas on the island i live on its 4.78 a GAL!! my 70 dart cost around 20 bucks to keep running on a daily average.
Author:  Aggressive Ted [ Sat Nov 22, 2008 11:08 pm ]
Post subject: 
Nico,

I haven't seen a cork fuel bowl gasket for years. Been buying the black fiber/composite type which seal very well. I think I have changed the jets over 20 times and still on the same gasket. Just use a little synthetic oil in the crease when you put it back on.

You can't go wrong with a #56 jet or a #57. They seem to work pretty well in the 1920. Glad you found some gaskets.
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