Looking for better fuel milage

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Lets see where do we start ?
What I see is a car that is set up for the strip,not gas milage.

Ok..To much advance at 40 for the street. Track maybe,but not for the street.
Timing should be between 10-12 initial 34 total,all in around 2500. Your car will be better on the top end anyways with this timming.

You "Must" have vacuum advance on a street car if you want any kind of milage.


Heres the fun part. Holley double pumper and gas milage = No Dice !!!!
Holleys are generally a race carb with high performance in mind.
Since you have an auto trans,you should be using a vacuum sec carb.
If you must use the Holley, jet down the primaries,lower the pump shot,and try to stay out of the secondaries. Sounds like the power valve department. Or put the carb into the trunk and cruise with a Ede 600. Put the Holley on when you get to the strip.

Tunning to be as lean as possible without hurting the motor is pretty key.
If your running around super rich,well there goes your gas.

Someone mentioned a vacuum gauge in the car. Helps you get better milage.
Lower the vacuum the more your getting into it. Try to keep vacuum up for milage.

Tires inflated couple pounds extra as mentioned.

And the all time milage tip.
Drive it like there is an egg under the gas pedal.
 
Took the Quick Fuel 650 Double Pumper off this pm and installed a new 500 cfm Edelbrock with manual choke. Also installed lighter springs in the dizzy. Full advance will be in at 2500 rpm's now instead of 4000.

Will drive it up to Indy Thursday pm. This small trip should give me an idea if I'm on the right path. Somewhere around 90 miles there and back.

With the Quick Fuel it was unbearable to stand anywhere near the rear of the car because of the odor. It's much better now with the Eddy.
 
You should get much better milage now.

Did you hook up the vacuum advance ?

Should be hooked up to the ported (passenger side) of the Edelbrock.
 
40* total timing just reaffirms that the compression is detrimentally low.
No heat with that lil squeeze, losing efficiency there.

Now understand that the power valve is designed so that you can use the leanest cruise jetting possible but under load/xelleration give the proper enrichment.

Carbs in general do not yeild poor milage, however poorly tuned carbs do.
Without a trained right foot the dbl pump can be hogish, but lets look at this.....
A vac secondary has an xellerator pump, so does the dbl pump
A vac secondary has a power valve, so does a dbl pumper
A vac sec is square bore, so is a dbl pumper, so cfm is split between 2 two barrels.
The common dbl pumpers are calibrated for street cars, just like the vac secondaries.

A lot of times the street calibrated carbs get lean in the r's, thats why the designer race carbs use a richer calibration...nt a bad thing cause you want the ideal ratio for max hp and to keep from puttin a hole in the piston.

If you can run 40*, have tried locking out the distributor to 40* and seeing if it will still start fine fully warmed up?
A higher initial timing will help power and milage as well.
I run 26* initial w/340 & 34* total, it wont start with any more initial.

You have too low compression, thats part of the problem.

for comparison-I run a 750 dbl and get 15-16 mpg w/ 280* cam and ported x iron on a 340
 
When I did my 71 340 Demon a few years ago I went with a stock build on the motor - tremec 5 speed - 355 gears and my friends thought I should go for more power etc and kinda laughed at me well ??????????? My next build is a 74 Scamp 318 for economy to see how many MPG I can squeeze out of it and how cheap I can do it.I think I can get it to at least 25 MPG range or better
 
You can more than double your mileage with a hidden HHO unit. Cheap and easy to install. You will have to up grade your alternator and your battery output to supply the system. Its the new way and it works. I believe summit sells the system. They use to be expensive. I have been playing with different systems including electronic methanol injection. You would not believe the systems on the market now. They auto tune 30% and you can save the trim. The system will start over at where it stopped with its AFR. You can set your throttle position percentage. It auto tunes from 5% throttle to 14300 rpm's on are car. This is not a typo yes 14300. The rev limit is set at 14800 and it loves it. They also have new anti gravity batteries. They vary from 3/4 lbs. to 4 lbs. We just bought one yesterday it weighs 1 1/2 lbs. 300 cca's it fit in my pocket $190.00. never needs a charge the hotter it gets the more it puts out. What I am trying to get at is do some research on the web there is so much out there for making your car more efficient. My Duster is a 416 with 13-1 comp. I run it on pump gas on the street. The motor made 829 @8000 on the engine dyno. Duster #2 made 693 at 7200. My super charged omni is run on pump gas, no dyno runs. If you look in the thread for (engine bay pictures) you can see the hho bottle, unit, and pump. Ethanol is coming get ready for it They make all types of systems for all types of motors with different fuels . I am playing wit a diesel truck I also have pictured. alot of these classics are going to be conversation pieces. Not mine, Im going to be tearing up the steets until they take em from me or cut me out of one. Go green!
 
Keep your opinions, just type in HHO or other items I mentioned. Do the research if you don't agree I don't really care.
 
HHO? What is that?

Tony, the entire car is set up for drinking gas like a wino out of weekend lock up. The biggest reason your mileage is in the toliet is the cam. Second was the Holley styled carb set up richly.

IF you wanna do the power tour without the power, install a small cam. Something close to a 2bbl cam. Chrysler advertised it at something like 252* w/.410 lift. Put the 2.76 gears back in. Keep the Edel. 500, though I'd recomend the 600.

IF you have stock 1.88 valved heads, swap them on.
 
rumblefish360 said:
HHO? What is that?

Tony, the entire car is set up for drinking gas like a wino out of weekend lock up. The biggest reason your mileage is in the toliet is the cam. Second was the Holley styled carb set up richly.

IF you wanna do the power tour without the power, install a small cam. Something close to a 2bbl cam. Chrysler advertised it at something like 252* w/.410 lift. Put the 2.76 gears back in. Keep the Edel. 500, though I'd recomend the 600.

IF you have stock 1.88 valved heads, swap them on.
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Since you asked here it is
HHO gas is used as the short or slang term for oxyhydrogen among the online community. Many online videos use the term HHO when demonstrating their electrolysis devices for improving car performance.
HHO gas is the product of electrolysis on H2O or pure water. Two individual hydrogen atoms and one oxygen atom. The actual chemical composition is H2 H2 O2. As each water molecule consists of two hydrogen and one oxygen atom two water molecules are required to complete the formula. The O1 from the first atom is an unstable free radical which reacts with the second oxygen atom from molecule two to form dioxygen, O2. The most common name of HHO gas is oxyhydrogen.
Electrolysis: 2 H2O → 2 H2 + O2
 
Thanks, but that didn't exactly answer my question. Thanks anyway.

Fringe science and fraudOxyhydrogen is often mentioned in conjunction with devices that claim to operate a vehicle using water as a fuel, or that burn the gas in torches for welding and cutting at extreme temperatures. Oxyhydrogen is sometimes referred as "Brown's Gas" after Yull Brown who advocated such devices, or "HHO gas" after the claims of fringe physicist Ruggero Santilli.

The most common and decisive counter-argument against using the gas as a fuel is that the energy required to split water molecules exceeds the energy recouped by burning it, and these devices reduce, rather than improve fuel efficiency.[12]
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As per the first link
 
What I'm guessing at is that you want to get the Hydrogen out of the water to burn as fuel.

They sell this at summit? LOL no way!
 
I have a couple of common rail Diesel dodge's. and I am sure there are other's out there that can verify this. If you ad a programer and you increase the fuel you get better mileage by almost 30%. Now why when your smoken black because of all the extra fuel would your milage increase? More power, less throttle, more efficient.Its one of the reasons I put a 05 cummins common rail in my 93 diesel, computor controlled fuel system. HHO does this and it free once you have the system. Water +voltage = Fuel/octane. Add it to any carburated motor no ECM needed. Its a no brainer.
 
Tony Fields said:
I am running a 2800-3200 convertor...Comp XE284 cam called for the convertor. My air cleaner is open 360 Degrees
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Tony,

I see your problem. The exhaust manifolds are restricting the breathing. Definately need headers. Plus, those valve covers restrict engine ventalation. Sell them to me and get a set of stock sheet metal gaskets. Plus, I bet that 8K tach is also somehow involved in the issue so it too should be sold to me.

Geeze, my 340 with the 850 doublepumper gets to the local pool bar and back with about 1/3 of a tank of gas. Problem is the gas tank sits in the trunk and only holds 5 gallons. May accidentally get some wheelspin on the road in front of my place to keep the decoration current.

3000 RPM and that little 340 is just starting to run right. 3.81 gears.

I am thinking a 360 based stroker may be the solution to better fuel milage.
 
Tony Fields said:
Took the Quick Fuel 650 Double Pumper off this pm and installed a new 500 cfm Edelbrock with manual choke. Also installed lighter springs in the dizzy. Full advance will be in at 2500 rpm's now instead of 4000.

Will drive it up to Indy Thursday pm. This small trip should give me an idea if I'm on the right path. Somewhere around 90 miles there and back.

With the Quick Fuel it was unbearable to stand anywhere near the rear of the car because of the odor. It's much better now with the Eddy.
Click to expand...

Sounds like you made a good move on it Tony :happy10: and I think a clutch fan will pay good dividends toward getting more MPG.
There are some great tech's here and I see allot of good feed back and help.
Only one thing I could think of is keeping the air out of the bottom of your car.
at 65 to 75 it would be nice to have the air split away from the belly and wheel wells with a front air dam to move the air around your car.
Do you have a set of 5 to 5 1/2 inch rims you could go with a taller skinnier tire for less drag, I plan on putting my light 13'' factory wheels on the front and make a couple passes at the track, the Ralley Wheels are heavy and the tires are to, Just stay safe and enjoy, from what I see in this post I bet you helped it allot :happy10:
 
Tony Fields said:
At present I'm only getting 8 mpg in town and 10-11 on the highway with the rpm's never over 3000 and only on the front two barrels. Carb is a Quick Fuel 650 double pumper. I'm running 66 jets in the front and was thinking about putting a plug in where the power valve is to see if it gets any better. Engine is a 360 +.060 with dished pistons in the hole so compression is around 8-9

Car runs great but likes gas. My setup is comp XE 284 with roller rockers and flat tappets. An Eddy air gap intake and Eddy Perf. RPM heads. I have a 3.55
out back with a 2800-3200 convertor.

The 'Cuda is a cruiser with a 99 % of the time.

Any info would be appreciated. Gonna do The Power Tour with it in June so I wanted a few more mpg if I can squeeze it out of it.
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Well, that explains why I only got about 3 miles to the gallon with my heavy foot testing out the stroker. I have no power valve in the Davinci 950cfm not sure what the jets are but don't think it will make much difference the way I drive it :burnout:
 
Tony, first off, I want you to know I ain't bashin on your car. I think it's a beautiful car. Probably among the nicest ones on the site. Or anywhere else for that matter. But man, your combination is just way mismatched to expect any kinda mileage.....and performance could be kicked in the BUTT with a few simple changes. First off, your compression is probably no more than 8.2 at the most. You say the pistons are dished and in the hole. Secondly, that camshaft is light years too big for that compression ratio. Doesn't really matter if you have the converter and some "better" gears. While that does help the manners of the car, it does nothing for the overall efficiency of the entire car. You would find mileage and probably snappyness too would severely improve if you installed a much better matched camshaft, a stock converter and 3.23 gears. The 340 camshaft would be a huge improvement, along with a stock converter and 3.23 gears.....also that carburetor ain't helpin a thing. A thermoquad might get you up to 20 MPG with all the other stuff. And from 0-60 would likely be quicker than what you have now.
 
StrokerScamp said:
Tony, first off, I want you to know I ain't bashin on your car. I think it's a beautiful car. Probably among the nicest ones on the site. Or anywhere else for that matter. But man, your combination is just way mismatched to expect any kinda mileage.....and performance could be kicked in the BUTT with a few simple changes. First off, your compression is probably no more than 8.2 at the most. You say the pistons are dished and in the hole. Secondly, that camshaft is light years too big for that compression ratio. Doesn't really matter if you have the converter and some "better" gears. While that does help the manners of the car, it does nothing for the overall efficiency of the entire car. You would find mileage and probably snappyness too would severely improve if you installed a much better matched camshaft, a stock converter and 3.23 gears. The 340 camshaft would be a huge improvement, along with a stock converter and 3.23 gears.....also that carburetor ain't helpin a thing. A thermoquad might get you up to 20 MPG with all the other stuff. And from 0-60 would likely be quicker than what you have now.
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Hi Rob
The reason that cam is in the engine is because the wife heard one at the speed shop back before my engine was built and she liked the sound of it. I've gotta agree, I like it too. Probably was a mistake but if I can manage 14-15 on the current setup I'll be happy. I don't really sweat the mileage around here, but a long trip.....every little bit helps.

When I come thru your area in June I'll have you drive it.

Later,
Tony

And thank all of you for your replies. I didn't really care if the car was a rocket, just wanted a nice sound. I got the sound I wanted but it may have cost me the mileage. I filled it up an hour ago and reset the trip. I'll know something in a couple of days.
 
rumblefish360 said:
What I'm guessing at is that you want to get the Hydrogen out of the water to burn as fuel.

They sell this at summit? LOL no way!
Click to expand...

Yeah in the snake oil department. Right next to the tornado air filter thingies and all that others junk.
 
Tony Fields said:
Hi Rob
The reason that cam is in the engine is because the wife heard one at the speed shop back before my engine was built and she liked the sound of it. I've gotta agree, I like it too. Probably was a mistake but if I can manage 14-15 on the current setup I'll be happy. I don't really sweat the mileage around here, but a long trip.....every little bit helps.

When I come thru your area in June I'll have you drive it.

Later,
Tony

And thank all of you for your replies. I didn't really care if the car was a rocket, just wanted a nice sound. I got the sound I wanted but it may have cost me the mileage. I filled it up an hour ago and reset the trip. I'll know something in a couple of days.
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I'd love to that'd be fun. I think those mileage goals are reachable with that cam. With a thermoquad.
 
there ar eplenty of good recomendations here, like the clutch fan but i was waiting for some one to recomend the thermoquad. i have to say if you are going to run manifolds, well you might as well ditch the single plane intake and go with a performer and a TQ or have a performer rpm modified to fit the tq. try the thermoquad guy here on the site demonsizler or something like that, see what he has to say about a carb. when you get it all figured out look into a 518 trans.
 
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