Gas mileage

[moparstuart]

I just went to branson and got 14 MPG on the 440 + 6 on the birdible. I was running 70 or so and trying to runn just off the center 2 barrel .
The motor is not really even broken in yet .

 

[mcmopar]

It has a 750 Eddy on it. A crap carb for sure but this one works pretty good in this app. I may rebuild one of my AVS carbs I have laying around and give it a try. You can run the Eddy strip kits as long as you use an AFB "hat" or fill in the AVS ones with JB weld or something.

If the newer Edelbrock jets can be used it would be better to use them rather than the metering rods because the old AVS's used a 3 step metering rod which gives more precise fuel metering. The Edelbrock AFB's use a 2 step metering rod which won't meter quite as precisely and cause an overly rich condition in the mid range (right where you are driving in the 50-60 mph range). Perhaps the new Edelbrock Thunder AVS parts would be a better fit. I'm not sure on that because I once called Edelbrock about this and their reply was that although the new Thunder is an AVS design, its all new since the old Carter molds and designs were lost years ago.

I just went to branson and got 14 MPG on the 440 + 6 on the birdible. I was running 70 or so and trying to runn just off the center 2 barrel .
The motor is not really even broken in yet .

That's doing well, Stuart. what gears do you have in it? You know, years ago I thought 14 mpg was poor, now I'd kill to get that much at 70 mph!

 

[Roadcuda]

Mcmopar, you're talking about the size of the jets and metering rods. I assume depending on the size of them that it would affect the gas mileage? I have a suspicion that the PO had set this car up for some sort racing so I wonder if the jets had been changed, I know he had changed the rear end to 3.91s. How can I tell what the size of the jets and rods are, and what size would have come from the factory? I do remember seeing them offered on ebay but I have no idea what the stock size is. BTY I am running a Carter 4682s. Thanks

 

[SomeCarGuy]

I think you can get by running the new jets and the old rods but I'm not 100%. Of course I would be pretty limited since I only have two AVS carbs maybe 3 so that is how many rods I have to use.

I have a HSD intake on there. I wondered if that might be the culprit but now that you say it is considered good one this front I don't know. :huh: I was only running it because it was on the shelf and nto cast iron.

I have dropped enough weight off the front that the manual steering isn't really noticeable now.

 

[moparstuart]

It has a 750 Eddy on it. A crap carb for sure but this one works pretty good in this app. I may rebuild one of my AVS carbs I have laying around and give it a try. You can run the Eddy strip kits as long as you use an AFB "hat" or fill in the AVS ones with JB weld or something.

If the newer Edelbrock jets can be used it would be better to use them rather than the metering rods because the old AVS's used a 3 step metering rod which gives more precise fuel metering. The Edelbrock AFB's use a 2 step metering rod which won't meter quite as precisely and cause an overly rich condition in the mid range (right where you are driving in the 50-60 mph range). Perhaps the new Edelbrock Thunder AVS parts would be a better fit. I'm not sure on that because I once called Edelbrock about this and their reply was that although the new Thunder is an AVS design, its all new since the old Carter molds and designs were lost years ago.

I just went to branson and got 14 MPG on the 440 + 6 on the birdible. I was running 70 or so and trying to runn just off the center 2 barrel .
The motor is not really even broken in yet .

That's doing well, Stuart. what gears do you have in it? You know, years ago I thought 14 mpg was poor, now I'd kill to get that much at 70 mph!

727 auto 8 3/4 3.55 gear I think this is just the perfect gear for my road tripping

 

[mcmopar]

Mcmopar, you're talking about the size of the jets and metering rods. I assume depending on the size of them that it would affect the gas mileage? I have a suspicion that the PO had set this car up for some sort racing so I wonder if the jets had been changed, I know he had changed the rear end to 3.91s. How can I tell what the size of the jets and rods are, and what size would have come from the factory? I do remember seeing them offered on ebay but I have no idea what the stock size is. BTY I am running a Carter 4682s. Thanks

I'd have to look into it and see what they were equipped with. I have a Carter carb book around here somewhere and I can ask a good friend of mine who runs a B/Stock Challenger. If anyone knows those part numbers he will - or else he will know someone else who knows.
Its been a long time since I messed with an AVS. I had one in my '71 Charger SE from a 440 and put some 383 metering rods in it to richen it up a bit. I'll post as soon as I can dig that info up for you.

727 auto 8 3/4 3.55 gear I think this is just the perfect gear for my road tripping

Yeah - I'd have to agree with you. Back when I went to Columbus for the '05 'Nats I was using a 3.23 Sure Grip. I don't see any mileage penalty with the 3.55 Sure Grip and its a bit snappier off the line. The 3.55 was the best all around gear IMHO.

 

[SomeCarGuy]

I pulled 3 plugs over the weekend that were easy to get at.

#1 and #8 both looked good. No real deposits on them, pretty good overall.

#7 appeared very oily and the gap was a little tight, so I opened it up to 35, which is what the others were at. I ended up swapping it to the #8 hole to see if it is a fluke.

Plugs are Autolite 85's, old made in USA set I have had for a long time.

 

[SomeCarGuy]

Creeped up today to 14.25

Was using a lead additive and octane booster in one bottle from Car Quest. I took back some stuff w/o paperwork so I had to buy some stuff in order to smooth things over, was worth a shot.

Could have went up due to the fan working right now. Could have been from the additive. COuld have been regapping that one plug and ,maybe it isn't fouling out now.

Also had front tires switched to see if the pull went with them, it did, but it drove a tad better so maybe that was it.

Timing was 9/33 for this. Happened to settle there while retiming after new oil pump install.

Will have to keep checking to see if it holds.

 

[SomeCarGuy]

After the new mufflers and head pipes w/ H pipe went on, MPG shot up to a new best of 15.25

 

[69hemibeep]

After the new mufflers and head pipes w/ H pipe went on, MPG shot up to a new best of 15.25

You keep this up and you wont qualify for your gas guzzler voucher :lmao:

 

[moparstuart]

After the new mufflers and head pipes w/ H pipe went on, MPG shot up to a new best of 15.25

You keep this up and you wont qualify for your gas guzzler voucher :lmao:

I'll give him the full 4500.00 for it :jester: :jester:

 

[SomeCarGuy]

I bet the alignment corrections might qualify it as a upgrade from some cars.

Maybe I could find a 85 Ramcharger like somebody has mentioned in a post about the program. Then I could upgrade to another 69 RR that gets better MPG.

I think a better carb and the alignment might get close to the 18 I think it has in it's reach.

I don't like this clutch either. A true CF might help a little as well. This one works but not like a true CF would I THINK. It might not make any difference.

 

[Blown R/T]

I just got back from Hot Rod power tour sunday. I was getting 25.5 average. a total of 20.8 including the long traffic delays and a few high speed interstate fun days. Madison Wi to Bristol Tn. 2045 miles in total. It was a blast. I had 2:76 sure grip.
Kevin

 

[SomeCarGuy]

Details on that combo please.

I had one get 22-25 but it was a real mild 383 combo.

 

[Plymouthfan]

I can't believe all you guys actually have accurate speedometers/odometers!

I've changed my rear, rear tire height and I'm pretty sure my trans may have been donated from a C body, which I heard throws the accuracy off. The only thing I haven't changed yet is the speedometer gear, LOL. My milage and speed is way off in my Runner. I have no idea what my milage is Although I do know it dropped a LOT since I switched from the small AFB to a 770 Holley

 

[jays69bird]

On a trip to Carlise I averaged 14 mpg thats with a basically stock 383 4spd and the top up.My 72 Charger SE 400 auto was lucky if it ever got any higher than 12 but that motor had been warmed up a little,69 heads,street Hemi cam,etc.

 

[ACME A12]

I just got back from Hot Rod power tour sunday. I was getting 25.5 average. a total of 20.8 including the long traffic delays and a few high speed interstate fun days. Madison Wi to Bristol Tn. 2045 miles in total. It was a blast. I had 2:76 sure grip.
Kevin

Man, that's amazing. My wife's '08 Caliber SRT4 only gets about 24 combined even with all of its modern fuel management systems and only four slugs going up and down... of course she's got her foot in it all of the time too... :wave:

ACME

 

[Blown R/T]

This car has the origional # matching 318, auto, and a new 8-3/4, 2:76 sure grip. not that the sure grip means anything! It had 72,000 miles before I left. (Origional) This car had sat since 1980. before I bought It. The engine was stuck when I bought it. I free'd it, did a crylon rebuild on it. (degreased, new gaskets, a timing chain set, and painted it with car paint acrylic enamel and a paint gun) I could'nt accualy paint it with a bug bomb!! It looks like new. The origional air cleaner element was there, and like new! (or new back then from a dealer) I used mopar hoses & belts, new date coded plug wires,windshield washer tank, new gas tank, brakes,The origional drums were almost like NOS. I dipped them in acid. Turned out like new!! New torque thrust wheels/BF,s radials. including the spare, new trunk floor, and painted the roof. it had a vinyl top. new carpet & head liner.
And had no time to test drive it. only to the way side (2 miles) I had this car stripped of glass & all the parts to paint it. and ran out of time. so I put it back togather again! It was a tough decision, but it has so many hail dents I would'nt have made it. if i am going to do it I want it real nice! It has cheap seat covers. I could'nt find real covers for a 4 dr. and we were off!. I only blew out the two rear shocks leaving detriot. on a severely rough off ramp! I was'nt the only one. I also put dual exhaust on it. with correct R/T tips & hangers. W/ flowmaster muffs. sounds nice! one tail pipe came out when I hit the bumps also. had to wire it up for a few miles till I could get to a safer place .
The trip was awsome.
would do it again!
Kevin

 

[Roadcuda]

I can't believe all you guys actually have accurate speedometers/odometers!

I've changed my rear, rear tire height and I'm pretty sure my trans may have been donated from a C body, which I heard throws the accuracy off. The only thing I haven't changed yet is the speedometer gear, LOL. My milage and speed is way off in my Runner. I have no idea what my milage is Although I do know it dropped a LOT since I switched from the small AFB to a 770 Holley

I know that my speedo is reading 5 mph slower then I'm really going. I figured that out by measuring a mile in 60 seconds. So that will throw off getting an accurate mpg reading.

 

[sam z]

Wow...a lot of interest in gas mileage. For me, my Prius gets around 45 MPG, and for the runner, is put around a 1/4 tank of gas through it a week, whatever that equates to I really don't know.