Fuel Economy

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Just_Fare
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Fuel Economy

Post #1 by Just_Fare » Thu Jul 19, 2018 11:14 pm

Hey folks,

I've got my '66 Fairlane with its mostly original 200 running about as good as I can get it and over the last 1200+ miles I'm getting 26.8 MPG combined city / hiway. That seems pretty good to me. Is there much room for improvement over that figure? I could probably get a little better if I drove like grandma, but I don't and won't. In fact I drive like a goon sometimes. The Fairlane has a '78 250 top end, Carter RBS carb, stainless header with 2" pipes and a steel packed Porter muffler, and HEI distributer.

Thanks as always,

CC

Soldmy66
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Re: Fuel Economy

Post #2 by Soldmy66 » Fri Jul 20, 2018 12:59 am

Most of the improvement comes from changes to driving style. I pretty easily increased the mileage on my G35 about 20% - just by following some of the simple types on Ecomodder(dot) com.

Their motto is "Adjust the nut behind the wheel".

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ludwig
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Re: Fuel Economy

Post #3 by ludwig » Fri Jul 20, 2018 4:23 pm

That Magnaflow 40 pretty much killed my fuel economy. I loved the sound of it accelerating and the added torque was the BEST.
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chad
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Re: Fuel Economy

Post #4 by chad » Fri Jul 20, 2018 5:59 pm

magna flow - a chambered rather than a turbo. I think the turbos R better w/mileage. I hear they're better for performance (MPGs & pep)...
Pumped up tires, lght break/throttle, lower unsprung weight, tune up...there must B 3 or 4 more MPGs boosters.
We had a fella here w/that as his 'name' here who did alota work on the topic...search his threads?
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", etc. Seeking: Hydraulic gear motor for Koenig pto. chrlsful@aol.com (413) 259-1749

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ludwig
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Re: Fuel Economy

Post #5 by ludwig » Fri Jul 20, 2018 6:45 pm

Pumped up tires, lght break/throttle, ...


What fun is that?
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Re: Fuel Economy

Post #6 by wsa111 » Fri Jul 20, 2018 7:01 pm

Getting over 25 MPG is fantastic. Your right foot is the deciding factor if A/F & ignition are perfect.
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, HEI dist. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
2003 Ford Lightning daily driver. Recurving Distributors. billythedistributorman@live.com
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Re: Fuel Economy

Post #7 by bmbm40 » Fri Jul 20, 2018 8:09 pm

That seems like very good mileage. What trans do you have?
66 Bronco-1970 250, NV3550, DSII, 4 turn ps, uncut, 1" bl, 2.5" sl, front disc, twin stick D 20, 30 x 9.50
NEXT- direct mount 1.08 on D8 head, power brakes, rear limited slip, 3G, electric fan, electric upgrades, custom curved DSII, header, 31" tires

New guy? Get the Falcon Performance Handbook and Ford six high performance parts from https://vintageinlines.com

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Re: Fuel Economy

Post #8 by rbohm » Fri Jul 20, 2018 9:23 pm

there is always room for improvement, depending on the money you are willing to spend to get there. driving style is the first thing to get right. beyond that you are spending time and money for various upgrades. and you need to select these upgrades wisely. remember to take a systems approach to your upgrade, by matching components to work together to achieve your goals.
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Re: Fuel Economy

Post #9 by CZLN6 » Sat Jul 21, 2018 12:01 pm

Howdy CC and all:

IF you got almost 27 mpg you are doing all right in the mileage dept. I'm assuming that you've already done all of the obvious stuff, am I right? Do you want a list of the easy stuff? What did your compression ratio end up at on the '78 head? What is the elevation where you drive?

In general, your best mileage will happen at steady, highway speeds, but never over 65 mph. Your worst mpg will be in town. So your biggest potential for improvement is in town. Given that, Avoid cold starts and idling. Consider a 95 degree thermostat. In general, an engine on the warm side will be more efficient. Also avoid idling- start up and drive off. An engine warms up faster and cleaner under way. Getting the choke open quickly and off of fast idle is the goal. Set the choke on the RBS to lean. The only adjust meant of the accelerator pump on an RBS is the bend in the bottom link. Adjusting it to less squirt will help most around town. Your carb rebuild sheet will tell you how to bend the link for more or less squirt. Plan your in-town driving to avoid stop lights. Anticipate stop and coast when ever possible and safe to the stop. Be considerate, safe and aware when in traffic.

Ironically, one of our best resources for MPG is/was Ak Miller. Ak is best known for performance mods on Falcon and Mustang sixes, but he was an early thinker on improving mileage on these engines. The Mobil Mileage competitions in the sixties and seventies were quite an event. Motor Trend got into them also. I have several articles somewhere but it would take me some serious digging.

Lastly, the RBS is not your best choice for a mileage carb. It is a great bolt-on upgrade for performance and simplicity. Are you committed to it, or would be open to consider a better mileage carb?

How about some feedback from you.

Adios, David
co-author of the Falcon Performance Handbook
http://www.falcon6handbook.com/

Just_Fare
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Re: Fuel Economy

Post #10 by Just_Fare » Sun Jul 22, 2018 11:13 pm

Thanks all for the advice and tips. To answer a couple of questions, my Fairlane has the C4 transmission and 2.80 gears. I'm running tires that are slightly taller then stock. I don't know the compression ratio but I aim to find out sometime soon. I guess I'm not committed to the Carter RBS but I have really enjoyed the performance boost. I had an Autolite 1100 originally. I live basically at sea level and there are not any substantial hills on the Island I live on. A lot of my driving is on country roads with few stops and there isn't really much traffic so I don't end up idling for any length of time. 65 MPH is about the speed I normally drive to and from work. I'll look into the thermostat.

CC

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Re: Fuel Economy

Post #11 by CZLN6 » Tue Jul 24, 2018 10:17 am

Howdy Back cc:

IIWIYS, I would optimize the RBS and the ignition advance curve for fuel economy before I spent any money trying new parts. I had considered recommending a two stage two barrel carb, but they are pricy and the cost-to-return ratio is iffy.

On the carb- The quick and easy carb setting is to set the low idle to the highest vacuum with a vacuum gauge. If/when you buy a carb rebuild kit it will include instructions for dealing with each of these parts and functions. There are good videos, on-line as well. Thoroughly clean, minimize choke time on cold starts and make sure that the choke opens completely. Reduce fast idle speeds on cold start cam. Consider minimizing the accelerator pump function. If you go too far in reducing the the pump you will notice a bog on off-idle acceleration. Reduce idle speed to just higher than stalling.

On the ignition- Set the initial advance as high as you can without pre-ignition. Get the internal vacuum advance set to the highest possible, but it will have to be coordinated with the initial advance setting. Get the centrifugal advance recurved to maximize your engine combo. The ideal ignition advance will take into consideration a balance between initial, vacuum and centrifugal.

You didn't mention whether you have already done the quick and easy steps to improve mpg. Have you?

Adios, David
co-author of the Falcon Performance Handbook
http://www.falcon6handbook.com/

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Re: Fuel Economy

Post #12 by Just_Fare » Wed Jul 25, 2018 9:35 am

Thank you David for the thorough set of tips. I will buy a vacuum gauge and compression tester today and run those test when I have a little time. Currently I haven't had a day off from work in two weeks and don't have one scheduled for another five.

I have the low idle set to where it feels right and doesn't stumble and that is 550 rpm. As far as the adjustments on the distributor itself, where would I find those?

The carb itself was rebuilt by a well respected automotive performance shop, I haven't rebuilt a carb before and didn't want to try that out on my daily driver.

What are the quick and easy steps that you mention? It's likely that I've done some but not all.

Again many thanks,

CC

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Re: Fuel Economy

Post #13 by CZLN6 » Sat Jul 28, 2018 11:07 am

Howdy Back CC:

The number one mileage tip is to air up your tires to about 10% above the "recommended max load" psi stated on the sidewall of the tire. For example, if the sidewall number is 32 psi, try 35 psi. Please note, increasing the psi will slightly alter the way your car handles so be cautious until you get used to the difference. For comparison, note the tire pressure before increasing.

Next would be to increase the initial timing setting to just below pinging. Your engines stock initial timing specification would be 10 degrees BTC. Start by setting the advance at 15 BTC. If you get pinging reduce initial advance by 2 degrees and try it again. IF you don't get ping at the 15 degree setting try 18 degrees BTC. This is a trial and error process. Ever engine situation is different so "try" is the only real "tell". You will need a timing light and something to plug the vacuum advance line to the carb to eliminate the vacuum advance from kicking in as you adjust the initial advance. With a stock cam and a 95 degree thermostat you may be limited to how much initial advance you can use.

Other free and easy tips are to lose weight (on the car, not you). Empty the trunk and back seat of any unnecessary clutter you don't need in the car. Drive with the windows up for less drag. Tune the low speed idle screw to the highest vacuum setting. This will require a vacuum gauge. A good gauge will cost you about $25.00. Remember to reduce the idle speed after setting. Gap the spark plugs to .050".

On recurving the centrifugal advance you will need help from an expert. It will involve adjusting the internal weights and springs to allow the centrifugal advance to begin sooner and coming in quicker. Bill (aka wsaIII) would be a good guide with your HEI distributor.

Beyond the mechanical aspects the only other ways to increase MPG is the nut behind the wheel. You mentioned that you tend to drive "like a goon". That aside, train yourself to not start the engine until you are ready to drive off. Avoid jackrabbit starts and coast to stop signs rather than stopping suddenly. Car manufactures rate new car mpg at a steady 41 to 45 mph. That's unrealistic and disappointing to new car buyers, but it works.

Finally, if you are already getting almost 27 mpg, be realistic. With all of the above optimized you will likely not see a big increase, but it's fun to try. Be careful, it can get obsessive.

Good luck and keep us posted.

Adios, David
co-author of the Falcon Performance Handbook
http://www.falcon6handbook.com/

Just_Fare
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Re: Fuel Economy

Post #14 by Just_Fare » Tue Jul 31, 2018 11:30 am

Howdy all,

I've picked up a compression tester and a vacuum gauge and plan to test the compression and try out tuning with the vacuum gauge sometime this week, probably tomorrow. I have a question about pre-ignition or pinging. I don't know what it sounds like and I haven't been able to find an online video that is helpful to me. I've read that pinging usually occurs under hard acceleration or load or up hills etc. The problem is that with the muffler I have, the car is fairly loud under all of those circumstances and I am afraid that I wouldn't hear it even if I did know what to listen for. It's whisper quiet at idle and cruising and only slightly growly around town but can get loud under load.

Any help is always appreciated and I will write back with my results from the testing as soon as I can,

CC

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Re: Fuel Economy

Post #15 by CZLN6 » Wed Aug 01, 2018 9:35 am

Howdy Back CC:

Try to read your spark plugs regularly. Try a cooler heat range when you buy new plugs. Look for signs of glazing and/or peppering on the white porcelain of the plugs. Both are signs of pre-ignition. Pre-ignition is more likely in summer heat. You will most likely hear pre-ignition on moments of load, such as up hill. Your car is geared pretty high- I seem to recall a rear gear of 2.80:1 so load on the engine should occur easily.

In addition to the vacuum gauge and compression tester, you may want to invest in a timing light.

Let us know what you find.

Adios, David
co-author of the Falcon Performance Handbook
http://www.falcon6handbook.com/

Just_Fare
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Re: Fuel Economy

Post #16 by Just_Fare » Wed Aug 01, 2018 1:11 pm

I just finished tuning the Fairlane using the vacuum gauge in the manner suggested on the archived Classic Inlines website and was able to improve the vacuum over my "playing it by ear" method. The vacuum gauge results indicated a richer fuel mixture, slightly more advanced timing and a slower idle speed. When in drive and stopped now the car runs at about 500 rpm and it is a very smooth idle. I've listened hard and cannot hear any sounds that sound off or like what is described as pinging. I'll be checking the spark plugs and running the compression tests soon.

I'll keep you posted,

CC

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chad
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Re: Fuel Economy

Post #17 by chad » Wed Aug 01, 2018 5:04 pm

Just_Fare wrote:Howdy all,
...I don't know what it sounds like and I haven't been able to find an online video that is helpful to me.
Any help is always appreciated and I will write back with my results from the testing as soon as I can,
CC


"a few very sm pebbles rattling in a tin can";
"ping, ping, ping, ping" rapidly and w/a bit of a lower pitch than that sound represents;
ahhh, playin a dulcimer w/lill hammers ona led pipe?
It would B so much easier to ask a local (dialogue) as even a puter sound system's off a lill.
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", etc. Seeking: Hydraulic gear motor for Koenig pto. chrlsful@aol.com (413) 259-1749

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Re: Fuel Economy

Post #18 by Econoline » Wed Aug 01, 2018 8:55 pm

Yeah, pinging sounds like spoons being rattle against one another and you'll notice a lack of power as well. The more you put you foot into it when it's pinging the louder it will ping and the engine won't respond as it should.
It ain't gonna fix itself

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chad
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Re: Fuel Economy

Post #19 by chad » Wed Aug 01, 2018 11:35 pm

"...the louder it will ping,,,"
don't do it much, not good 4 engine.
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", etc. Seeking: Hydraulic gear motor for Koenig pto. chrlsful@aol.com (413) 259-1749

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