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What fuel Mileage do you get with your 5th Ave?

Posted By: 76dodgeboy

What fuel Mileage do you get with your 5th Ave? - 10/09/12 04:36 PM

I posted asking what headers etc will fit a 5th ave. I wanna know what you guys are pulling down for mileage in yours and what your combo is. Also what size tanks do they have? Mine might need a carb swap and leanburn delete already .
Posted By: warpspeed

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 04:56 PM

you need to check out dippy.org. They are the M body pros. Might find out more information there too. I think I only get 15 MPG. I have a highway gear and still can't get good mileage. I am not going back to the lean burn to get better mileage either.
Posted By: QuickDodge

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 05:13 PM

The origina EPA estimates were 16 mpg city and 22 highway for a 1985 model year 5th Avenue. The EPA has since revised all of their mileage figures. The new mileage figures are 15 city and 20 highway.

It's interesting to compare the 5th Avenue's mileage figures with the 1985 Diplomat POLICE car's mileage. (The civilian and police cars are rated separately) The EPA's original estimates for the police car were: 13 mpg city and 15 mpg highway. The EPA's revised figures are: 11 mpg city and 14 highway.

The civilian Diplomat's mileage ratings are identical to the 5th Avenue. So the question is why did the police Diplomat use so much more fuel than the civilian cars?
Posted By: DaytonaTurbo

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 05:23 PM

In the mid 90's my dad had one with a slant. He said he got low 20's with it on the highway.
Posted By: buildanother

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 05:44 PM

Had an 87 in about 1996, it had no gear but got at least 22 highway. With the lockup it was barely spinning the 318 on the road.
Posted By: dogdays

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 06:46 PM

My Mom's 86 would knock down consistant 25s on the highway at 65 - 70 mph. That car had something like a 2.21 rear gear so the low First in the A-998 was a real help. Funny thing, it didn't seem slow.

That's the engine I'm building for my '64Dog.

After 100K miles, there is virtually no ridge in the cylinders and all the valve seats and guides are usable. Those engines never had to work hard because the two-barrel carb wouldn't let them, along with the blue-haired old lady driving them!

R.
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 09:15 PM

Quote:

The origina EPA estimates were 16 mpg city and 22 highway for a 1985 model year 5th Avenue. The EPA has since revised all of their mileage figures. The new mileage figures are 15 city and 20 highway.

It's interesting to compare the 5th Avenue's mileage figures with the 1985 Diplomat POLICE car's mileage. (The civilian and police cars are rated separately) The EPA's original estimates for the police car were: 13 mpg city and 15 mpg highway. The EPA's revised figures are: 11 mpg city and 14 highway.

The civilian Diplomat's mileage ratings are identical to the 5th Avenue. So the question is why did the police Diplomat use so much more fuel than the civilian cars?



they have an 18 gallon tank.

dippy cop cars had a 360 top end (heads, intake, and 4bbl carb)

the 2.21 rear gear kills mileage in town...I could usually get 13 in town stock. best I ever got was 25mpg going to detroit and back, and that was with the cruise set near 80mph. set the cruise at 65-70 and mileage was about 23. that was stock. mixed driving was pretty consistant at 18mpg....once I modded for power, mileage went down, even with the A500 OD tranny. never took it on a full highway trip in it's last incarnation (mag headed 318 roller cam motor, A500, 3.55 rear gears), but it was very consistent at 17.5mpg in mixed driving, so it probably could've knocked down 22-23 all highway, and probably could have been even better with a t-quad or one of the new street demon t-quad clones over the 600 eddie AFB I had....a FAST EZ_EFI would have been neat to try, too...

that said, my '11 charger R/T is faster, more comfortable, and handles better, and for the 8k miles I've owned it, the same commute I averaged my rock steady 17.5mpg in the modded 5th, I'm averaging 23mpg...

a 5.7/A580 would be sweet in one if you could pick one up cheap enough. would require significant mods to fit the tranny in. a 5.7/A833OD would also be a fun combo, coupled with a 3.23 rear, and would probably knock down 25mpg highway....
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 09:21 PM

Quote:

My Mom's 86 would knock down consistant 25s on the highway at 65 - 70 mph. That car had something like a 2.21 rear gear so the low First in the A-998 was a real help. Funny thing, it didn't seem slow.

That's the engine I'm building for my '64Dog.

After 100K miles, there is virtually no ridge in the cylinders and all the valve seats and guides are usable. Those engines never had to work hard because the two-barrel carb wouldn't let them, along with the blue-haired old lady driving them!

R.



I *THINK* they came from the factory with moly rings...or the blocks have A LOT of nickel in them.

what heads are you going to use? the stock 302's? send your roller cam off to bullet cams to get reground. have them put their HR259/326 lobe on the intake and their HR266/325 lobe on the exhaust. it'll wake things up significantly while still having nice road manners and economy. if the roller lifters are in good shape you can reuse them. you may need to buy longer pushrods (or get the heads milled a little bit) and you'll want to swap springs with some hughes #1110's....
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/09/12 10:07 PM

The car will see 75-85% highway use as we live about 30 miles from work and I29 is the route to work. Would the 195s eat more gas than the stock 205 size thats suppose to be on it?Its at 113 miles from when I picked it up with a full tank and seems to be an 1/8 above have tank So my guess is currently around 14mpg. Pretty sure carb needs a rebuild and possible bad gas that was aparent after I got it home. Ran pretty good down the interstate. Is there a diff between car and truck 4bbl kickdown linkage? I have a few truck ones
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/10/12 05:50 PM

well, 195/75R15's are 1/2" shorter than the stock 205/75R15's...it's 2% difference. so....if 75mph was 2000 RPM with the stock tires, it would be 2040RPM. negligible difference. assuming a dead-nuts speedo and odo with stock tires, 60mph indicated would actually be 58.9mph. 100 miles indicated driven would actually be 98. so it would skew your gas mileage calculations the other way (overestimating miles driven).

don't trust the gas gage. on my 5th ave with the 360 in it, it would go 150 miles to 1/2 tank, and be near E and the low fuel light would come on at 225-240 miles, and take about 15-16 gallons to get to full. with the mag headed 318, I typically got 280 miles before the low fuel light, and it would take about 16 gallons to fill, with 180 miles on the trip odometer at 1/2 tank...
Posted By: Erics5th

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 02:10 AM

How my 5th is set up: 318, Performer intake/1406 carb, HEI ignition, lock up trans with a Superior TF-TC shift kit (mainly to raise the lockup speed), 8 3/4 rear with 2.94 gears and 215/70R-15 tires. When I did a daily 80 mile round trip commute, it would usually get around 22 MPG at 65, a little less at 70.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 02:58 AM

Might have done better with a 500cfm. Im shooting for 25mpg
Posted By: WO23Coronet

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 03:22 AM

My parents had an 82 and an 86 in the early 90's, on the highway (95% of the driving) they got 22-24 mpg, stone stock nothing done to them at all, running 205/75/15's. And they had those ridiculous 2.21 or 2.45 gear sets.
My brother had an 82 Cordoba with a low mile 1990 318 in it with a thermoquad, MP 430/450 260/268 cam and dual exhaust. With a 2.94 8.25 diff he also got low 20's on the highway. Pretty zip to, would beat a 5.9 Durango R/T in a street race.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 03:34 AM

Well if I hit 25 I'll up my goal to 28-30
Posted By: Erics5th

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 12:49 PM

When I first bought my 5th, my friend that I bought it from had an old Edelbrock SP2P 4bbl manifold on it and a Holley 4360 450cfm (an economy replacement for Quadrajets) on it. It did about the same for milage. Had great low end torque with the small runners though.
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 06:23 PM

Quote:

Might have done better with a 500cfm. Im shooting for 25mpg



then stay away from the AFB/squarebore carbs and go for a T-quad/q-jet or the new street demon.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 09:38 PM

Why?
Posted By: scratchnfotraction

Re: What fuel Mileage do you get with your 5th Ave? - 10/11/12 09:57 PM

the primary triple venturie on a spredbore is why a q-jet/thermobog do so well on the mpg.

small primarys for great throttle responce,triple venturies do better at atomizing the fuel into the air mix. very tunable with 3 step needles and jets(eddies are 2 step needles)

when you are on the 2ndarys there is no consern with mpg. it is all about the s**t and get.

work on everything from a 273 to a 440 for street duty and mild performance.

not to mention they sound kool when they open up and dont have any bogs to them.

I can stomp my 318 with q-jet from a 650 rpm idle to a full WOT run with no bogs,gets 19+ mpgs in the truck if i drive like "Ma & Paw kettle"

cant wait to get the q-jet from the 454 chebby set up for the 440 truck myself. I am shooting for anything over 10 mpg with it.

stock 440,q-jet,3.23 should do a little better than the eddy 600cfm with 3.91 gear.

I am just glad I get 19+ with the 85 truck as a daily drive 80 miles perday round trip.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 12:09 AM

I have a stock 4bbl carb from an 85 360. That a thermoquad and would that work or is it to big?
Posted By: scratchnfotraction

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 01:12 AM

may need tuning/rejetted but would work as it is a SB thermobog. it will have the smaller primary bores compaired to larger primary bores of a BB thermobog.

may need the same tuning with any q-jet or other carbs brands as well,if you want the most from it.

I use a chebby 327 q-jet on my 318,very close on jetting and tuning.

the q-jet from the 454 should be in the ballpark for the stock 440.

dial them right in with a vac gauge and get the 2ndary airdoor adjusted just right and no bog on the transition tip in.

and the q-jet is cheap to rebuild and mod o fry.

if you stay with a chebby carb the fuel inlet is to the side,the GM/GMC/pontiacs are front feed and can interfear with the rad hose/t-stat location.

you can get the short q-jet inverted flare fitting and ditch the filter to shorten it up some.

grind the chebby throttle lever off and tac a mopar q-jet lever on and all the stock linkage works with the early non emissions chebby q-jets with looking for a carb.

the carbs that have 704**** as the first 3 digets in the # are the bestest...ones with 1704*** or next bestest when junkyarding for them.

if you know how and can fine tune a thermobog it may out do the q-jet.

q-jet areless work tuning. i dont get the how to on thremobogs
Posted By: Remy-Z

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 03:22 AM

Going off my Mirada's numbers, due to it being a kissing cousin, I've seen a measured 24mpg average HWY. I'm measuring the actual mile distance, haven't had a working speedometer in months and a working odometer since 2010.

Combo:
323ci SB (original 318 with work)
Shift-kitted A904
Hooker B-body headers
2.94 SG AHB Diplomat rearend
235/70R15 front, 255/70R15 rear tires
Posted By: demon

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 03:23 AM

I drove an 80 Diplomat every day in 96-98. It was a stock 318 with lockup converter and high gears-2.45 I think. Only mods were electronic ignition and dual exhaust with glass packs. It got 27mpg Canadian (22 1/2 US) on the highway in 90 degree heat with the A/C blasting. Great car. Shoulda kept it.
Then I got a 86 5th Ave with same driveline but lean burn still functioning. It would get 25mpg Canadian (20 1/2 US) on the highway. The low first gear gave them enough power to pull out without feeling sluggish. Great cars. Both were super reliable.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 03:53 AM

What carb did you run Patrick
Posted By: chargincharles

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 10:53 AM

Quote:

I posted asking what headers etc will fit a 5th ave. I wanna know what you guys are pulling down for mileage in yours and what your combo is. Also what size tanks do they have? Mine might need a carb swap and leanburn delete already .



The first summer I had my 82 Fifth, Stone Stock- between 15-18mpg city, and 18-22 mpg highway. Really depended on how hard I pressed the 'GO' pedal...

Today-
318--Magnum Heads- Hooker Headers- Full 2 1/2" Dual Exhaust system connected to headers and with Flowmaster Mufflers (no Cats)- Crosswinds Intake- Carter AVS carb- Jegs Cam- HEI Ignition (leanburn delete, emissions delete)- recurved distributor- A/C Delete- High flow Water Pump- 3-core replacement radiator- Aux Oil and Transmission Coolers- B & M shift-kitted trans- 3.55 Sure-Grip 8 1/4 rear- 205's sized tires.
Makes TONS of power down low, and runs all day long at 75-80mpg on the highway with zero issues-(just higher RPMS)...and will beat most modern cars hands down. And fuel milage-

10-12 mpg city, 12-15 highway.
Again- depends on the 'GO' pedal and how hard I stomp it.
I also need to run Plus gasoline (89 octane here) because I get some pinging with 87 (regular) and 93 burns tooooooo fast...as in...I like to push that pedal too much when I'm running premium. The Magnum heads up the CR from the dismal 8.5- something to more like 9-something.

Keep in mind that the 5th is basically about as aerodynamic as a Cinder Block, has a large V8 and is choked with more emissions equipment that just about anything I have ever worked on. You are LUCKY to get the kind of milage I got when she was stone stock.

Any way you slice it- a 5th ave is NEVER a good fuel economy car. What it is- The nicest riding Luxury-type car I've driven in quite some time. And Also- About the biggest SLEEPER car I can think of.
No one expects the Grandpa-mobile to eat their lunch in a drag race. That's what makes it fun!

Just my pennies,
CC.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/12/12 04:04 PM

COnsidering I don't like new cars or can't afford the ones that appeal to me. 20mpg is fuel efficient to me. If scratch can get upper teens to 20mpg in an 80s truck I should be able to get low 20s no problem

Has anyone used the E3 spark plugs Do they really do what they say or are they just an overpriced gimmick
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/13/12 02:51 AM

Quote:

What carb did you run Patrick



the electric choke 600 eddie AFB, IIRC I had it jetted down 3 steps on the primary and 2 steps on the secondary to lean it out to ~14:1 on cruise and 12:1 on WOT
Posted By: Dragula

Re: What fuel Mileage do you get with your 5th Ave? - 10/13/12 03:13 AM

21-23 highway...Averaged over 17 all the time with a 318 and lean burn removed in favor of an orange box ignition system and distributor.

Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/13/12 03:21 AM

Lean burn Delete is quick approaching. Runs a little rough and the idle screw isn't long enough to use so the fast idle screw is dual purpose. Was thinking orange box as my other 5th we used orange.
Posted By: HotRodDave

Re: What fuel Mileage do you get with your 5th Ave? - 10/13/12 03:25 AM

I get around 22 on the highway 15 in town. No one is buying it so I am building a superduper MPG 318 EFI magnum motor for it, hoping for 30 MPG hwy.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/13/12 03:31 AM

Where was it listed for sale?
What mpg did you average. Im going to have a hard time trying Not to do 70
Posted By: HotRodDave

Re: What fuel Mileage do you get with your 5th Ave? - 10/13/12 03:38 AM

Moparts and Craigslist. It is a super clean 86 survivor
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/15/12 12:03 PM

Quote:

I get around 22 on the highway 15 in town. No one is buying it so I am building a superduper MPG 318 EFI magnum motor for it, hoping for 30 MPG hwy.



sweet. be sure to document the build for us to watch vicariously....
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/15/12 12:04 PM

Quote:

Where was it listed for sale?
What mpg did you average. Im going to have a hard time trying Not to do 70



my 5ths stock got ~2mpg better at 75 compared to 65....gearing is almost too tall....
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/16/12 04:21 AM

I might be getting around 21 driving at 55-65. I reset the odometer before actually Knowing what the mileage was but I think I remembered what it was. We'll see this week. put over 200 miles on today and is just under half tank. I was pretty sure it was at 240 on trip odometer and took 11 gallons to fill But not 100% it was at 240. Those is also with rough idle do to needing Lean burn delete
Talked to an exhaust guy and he recommended 2.5 single for the car so when the cash is available and I have the headers exhaust shop I will go
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/16/12 01:06 PM

if you don't have a shop that mandrel bends or you can't weld your own up from pre-bent mandrel bent section, personally, I'd just go with this setup from summit

lots of guys on dippy.org have used it. you just have to move your gas tank over 1 rib...
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/16/12 04:13 PM

I would if it wasn't 2.5". As the exhaust guy stated 3" is a bit much for a stock 318 and running dual 2.5" is more flow than single 3". He said it would create less backpressure with just a single 3". Having him build the 2.5" single is about the same price as that kit with an H-pipe.
Posted By: 67autocross

Re: What fuel Mileage do you get with your 5th Ave? - 10/18/12 01:59 AM

This one would pull in the low 20's on the highway with the 2 barrel and 2:40 gears and the lean burn changed out and dual exhaust.

Attached picture 7425260-P1010178.JPG
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/18/12 03:10 AM

I haven't checked my gr ratio yet but if its 3.23s I'll be looking for something in the 2.xx. I haven't gassed up or driven it since Monday but Im hoping its getting high teens low 20 bit driving around at 60 sucks
Posted By: HotRodDave

Re: What fuel Mileage do you get with your 5th Ave? - 10/18/12 03:42 PM

Mine is so quiet and smooth I often find myself cruising much lower than the speed limit, guess I am getting old as I do really enjoy driving this thing (Insert Old man walking with a cane smiley here!)
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/18/12 06:07 PM

Quote:

Mine is so quiet and smooth I often find myself cruising much lower than the speed limit, guess I am getting old as I do really enjoy driving this thing (Insert Old man walking with a cane smiley here!)


I like driving it. I had a gold one just like yours. If you'd have been closer and I saw it Id have jumped on yours but I only gave $850 for this obey with a new battery and tires with about 300-500 miles object them and a full tank if gas. Interior needs some tlc before may but Mainly the headliner. Needs a grill and center piece between tail lights and I hope to get it painted.
Just ordered the headers and some air shocks to bring the back up a little and to fit 215s a little better when they go on
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/18/12 06:09 PM

Here's a pic as it sits with 195s

Attached picture 7425967-2012-10-1018.59.37-1.jpg
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/22/12 11:48 PM

Im being told object another forum that headers and a 4bbl and later on an rv cam will make my fuel mileage go down. Even with just headers and 4bbl Its getting the summit G9040 headers and single 2.5" all the way back and I plan to use the 4bbl carb from the 85 dodge 4wd I scrapped. Im on the hunt for a cheap aluminum 4bbl to cut weight and plan to run an electric fan and would like to find some underdrive pulleys if they would really help and aren't to pricey. Also might swap to an aluminum radiator later and want to ditch the power windows to lose more weight. And eventually some aluminum wheels for even more weight reduction.
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/23/12 04:43 PM

it's all in the tuning, but for mileage (at least highway mileage) it's hard to beat the stock lean burn setup.

the window regulators are riveted in, and door panels different from power to manual apps...would be way more work than the ~20lb weight savings is worth.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/23/12 09:08 PM

I was told its the same panel. Gay said it has the spot to knock out for the window crank already. I also don't want to spend $50+ when a motor goes out and the passenger side front is Slow going up.
Car Will see 80-90% highway use
Posted By: patrick

Re: What fuel Mileage do you get with your 5th Ave? - 10/23/12 09:47 PM

take the door apart and thoroghly clean and regrease the linkage and track. you'll be suprised at how much better it works.
Posted By: 76dodgeboy

Re: What fuel Mileage do you get with your 5th Ave? - 10/24/12 12:46 AM

Will do
I haven't bothered to look yet but where can I get the fuzzy strips etc for the windows. Driver window won't track right if if at speed and doesn't go in its groove
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