Author Topic: MPG, Part 2  (Read 27147 times)

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3284
Re: MPG, Part 2
« Reply #90 on: December 13, 2017, 07:30:43 PM »
Wed 12/13

270.8 miles / 16.716 gallons = 16.19 mpg   :-\

$2.399 per gallon regular at mobil,  $40.10 to fillup

Offline justin_jj_taylor

  • Newbie
  • Posts: 5
  • -
Re: MPG, Part 2
« Reply #91 on: December 20, 2017, 06:40:20 AM »
So you got worse mileage on the Mobil fuel or the Shell fuel? I'm currently working on a 1979 1 ton with a rebuilt 350 that has had issues for quite some time now, finally just discovered that there's water in the tank, which keeps causing issues in the carb. We believe the culprit is poor fuel. Regardless, there's really no other way that water could have got into the tank besides poor fuel quality, so I think your biggest opponent now is wherever is offering worse fuel!

Offline Irish_Alley

  • Tim
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13299
  • Family is not an important thing. It's everything.
Re: MPG, Part 2
« Reply #92 on: December 21, 2017, 07:41:31 PM »
could you have a hole in the top of the take or the seal for the fuel pump assembly isnt intact or isnt in place
If you canít tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3284
Re: MPG, Part 2
« Reply #93 on: December 25, 2017, 02:06:08 PM »
So you got worse mileage on the Mobil fuel or the Shell fuel? I'm currently working on a 1979 1 ton with a rebuilt 350 that has had issues for quite some time now, finally just discovered that there's water in the tank, which keeps causing issues in the carb. We believe the culprit is poor fuel. Regardless, there's really no other way that water could have got into the tank besides poor fuel quality, so I think your biggest opponent now is wherever is offering worse fuel!

According to the log, i tend to get better mpg with Shell.

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3284
Re: MPG, Part 2
« Reply #94 on: December 25, 2017, 02:08:13 PM »
Fri 12/22

281.2 miles / 18.071 gallons =  15.56 mpg  :(

$2.429 per gallon regular at Mobil, $43.89 to fillup

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3284
Re: MPG, Part 2
« Reply #95 on: December 31, 2017, 09:42:13 PM »
Sun 12/31

284.5 miles / 17.582 gallons = 16.18 mpg  :(

$2.499 regular at Mobil, $43.94 to fillup

Lame.

Offline juggernaut6625

  • Newbie
  • Posts: 21
  • Newbie
Re: MPG, Part 2
« Reply #96 on: January 03, 2018, 06:03:37 AM »
i don't run ethanol free----can't find it.  We have, i think E10 and some stations have E15.  Going thru the thread, i noticed that i tend to get better mpg when i fill up at Shell.  But i don't think this is conclusive at this point.

i don't think running efi is the ONLY way to get over 13mpg, although it probably will help.   i don't know anything about Edelbrock carbs, but i run a quadrajet and i think it's a pretty good way to go, not just for mpg, but overall.

What are the specs on the engine?   Also, if you look at the SPID sticker, this can help determine what rear axle ratio you got.
[/quote]

My SPID reads G01 rear axel - standard K34 Electronic speed con, LE9 5.0 liter v8 GAS, MX0 4-spd Auto Trans.

Offline Coasting2aStall

  • Newbie
  • Posts: 15
  • Newbie
Re: MPG, Part 2
« Reply #97 on: May 01, 2018, 04:42:16 AM »
Not sure if original poster has lost interest or not.  But interesting real world fuel mileage thread, both part1 and part2.  My experience from decades ago plus a few observations might be of interest on this topic. 

Way back decades ago I bought a 1971 Buick LeSabre with 31k miles and 350 Buick V8 (when GM divisions had own
 unique inhouse V8)  Had TH350 and 3.08 rear end.  This was pre-pollution era, points ignition, no overdrive or lockup converter.  Got 13mpg in town and 22mpg on long trip.  This is 4200 pound car.  The later pollution era version of this engine in similar weight car got 14mpg tops.  Buick 350 ended in 1980.

Moving forward I had a 73 C20.   350 Chevy V8, TH350 (not sure why it didnt have a TH400), and I really dont remember its axle ratio.  It got 8mpg.  I was not impressed.  Well until it threw a rod through side of the block, then less impressed.  Needing to get it back on road cheap as possible, I looked in shopper paper for something cheap to put in it to get it on the road.  Found a pre-pollution Buick 350 for $100.  Made some custom engine mounts and bolted it in.  Yes the top two bolts on Olds/Pontiac/Buick enginesI  were different from Chevy, but you can bolt it up to chevy transmission without them if you have to.  I  reused the big bore 2bbl carb from the Chevy engine.  Got it going.  This 5000 pound truck got 16mpg!   For anybody not familiar with 3/4 ton from this era, 16mpg is pretty darn good, amazing with a 350 and  3spd automatic.  Now this is 2wd. 

Now been thinking lot about this after past couple years battling a high mile 1994 Ranger with 4.0L V6 and manual transmission where at one point it was getting 9mpg.  Yea really.  I am old man and not big fan of computer engine controls.  But finally got it back to 12mpg city and 16mpg hiway.  The devil is always in the details and on computer engine, there are a LOT of details.  And yea the OHV 4.0L though very durable engine, truly not very good mileage despite all the computer stuff.  I find it ironic that a compact Ranger gets same mileage as that old C20 with the Buick engine and automatic, and not much better than my 6000 pound 4wd F250 with non-computer carb six.  Tell me again about progress we've made protecting the environment...  How again do we pollute less by burning more fuel?  Is EPA secretly run by Exxon?

But I digress.  Having thought lot about my experience with the Buick and C20 while suffering 9mpg with the Ranger,  and reading online about SBC fuel mileage.  Came to conclusion fuel mileage in carb V8 mostly revolves around camshaft profile and of course distributor advance curve.  This assumes you have an appropriate size carburetor that is tuned for that particular engine.  Most non factory carbs get way oversized and not jetted properly.  Same with huge exhausts people think they need that kill low end torque.  Seriously a fuel efficient vehicle probably only rarely go over 3000rpm, you dont want it set up for racing where you pump most gas/air through it for super high rpm race track speed.  Just makes it painful in traffic.

Now saying this from searching and reading various forums.  For stock carburetor SBC the best economy cam that gets mentioned again and again is the GM cam used on the pre-pollution 327 that they referred to as the 300hp cam.  Thats a cam that has 194/204 duration at 050 inch lift.  Lot clones of it, but best deal for SBC probably the Summit 1101.  When I actually got to searching amazing how popular this cam profile is on older flat tappet cam engines of all makes.  If you look enough you can find this profile cam for lot of old engines even the straight sixes.  Though availability fading away as those engines fade away.  The first generation SBC was just super popular so cheap parts continue for it... to certain extent. 

Now to curve a distributor without a machine made for this purpose is lot trial and error changing springs and such on centrifugal advance.  But the modern world does offer some interesting aftermarket shortcuts.  Not particularly cheap but interesting.  Where you have a magic box that you can hook to laptop and program the advance curve you want.  I can only say I have read about them not used one.  But if I were trying for best gas mileage, I think I might if I wasnt having any luck playing with springs and such. You lock down any centrifugal or vacuum advance and the magic box does the work.  There is a programmable MSD box for like $400 and some lot more expensive.  Ouch.  But found two cheaper.  This one is around $200:  http://www.cbperformance.com/product-p/2013.htm  And here is link to a thread where there is lot discussion.  https://www.thesamba.com/vw/forum/viewtopic.php?t=606203&postdays=0&postorder=asc&start=0
 Yea its by company specializing in VW stuff but its universal, can use it with any distributor engine except odd fire V6. 

The other is around $300:  https://www.retromotioninnovations.com/   This one seems to have lot better thought out software to program it and can connect directly to laptop with usb cable rather than having to use a serial to usb conversion cable.  Whether its worth the extra $100, have no idea.  Like say I dont have any personal experience with any of the magic boxes.  But if I am going to computerize, then being able to do my own tweaking rather than rely on big brother seems way to go.

Offline Coasting2aStall

  • Newbie
  • Posts: 15
  • Newbie
Re: MPG, Part 2
« Reply #98 on: May 01, 2018, 05:13:04 AM »
Oh yea, been reading about the 4.3L V6.  You can get that same profile cam for the TBI versions.   None for the Vortec with the balance shaft unless you can get one custom ground.

Oh, bit trivia I picked up, the 1990-91 Astro van seems to had best factory camshaft profile.  Though probably worthless info.  No idea why just those two years and just in the Astro.

I suspect you might get a C10 to top 20 with a carburetor V6, but probably only with five speed manual and right cam, etc.  I personally rather attempt it with 250-6.  People understimate the straight sixes they are not like a V8 or modern V6 or even OHC straight six.  There was an thread I think on the 67 to 72 Chevy pickup board.  Without changing anything else some guy put a progressive Weber 2bbl from Vega or Pinto or something on his straight six and got 19mpg.  Dont remember now if that was a 230 or the 250.  He of course had to rejet it.  But Weber is very tunable. 

I have owned three half ton Chevies from 60s.  The 1960 Apache 10 with 235-6 and granny four speed got 16mpg.  The 66 C10 with 230-6 got  about same.  The 67 C10 with 283-8 and three on the tree got around 15.  NOne of these were geared for economy.  They were farm trucks.   Put say 3.27 rear in the 1960 and probably got 20 just from that change alone.

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3284
Re: MPG, Part 2
« Reply #99 on: May 09, 2018, 07:02:24 PM »
Haven't lost interest----i've had the truck parked for the last 4 months because i didn't want to drive it in the snow.   i will be switching back to it soon.


Thanks for the writeup.

Offline Coasting2aStall

  • Newbie
  • Posts: 15
  • Newbie
Re: MPG, Part 2
« Reply #100 on: May 15, 2018, 05:00:22 AM »
http://www.hotrodders.com/forum/67-camaro-327-rebuild-gas-mileage-help-137498-2.html

Having read heck of lot stuff on fuel mileage with carb engine, thread above contains some of best advice I think.   I do agree with their opinion that people overdo the gearing in the quest for bit extra fuel economy.  You might get bit more gas mileage, but you lose lot drivability.


Offline Coasting2aStall

  • Newbie
  • Posts: 15
  • Newbie
Re: MPG, Part 2
« Reply #101 on: May 17, 2018, 01:09:32 PM »
Truly annoying, keep thinking about what kind mileage I could get in full size pickup with non-computer carb engine mostly with cam I mentioned and one of the magic boxes for custom distributor advance.  And to do experiment on the cheap.  I dont want to spend lot money rebuilding lot stuff or buying crate engines or the like.  Thing is I dont drive enough anymore to need another vehicle or for fuel mileage to matter that much.  Long as fuel mileage is double digits (single digit fuel mileage truly sucks) then life goes on. 

But I get an idea in my head, really like to see if it works.  And not wanting some big body restoration basket case like most affordable antiques tend to be.  Newer half tons have gotten amazingly heavy too, up there similar to older 3/4 ton and usually long cabs and short boxes.  Maybe a Ranger/S10/Dakota, the 90s era compact trucks weigh nearly as much as the full size 60s and 70s  half ton trucks though alas none had 8 foot bed on them.  Least not that I know of.  Manufacturers didnt want them competing directly with their half ton full size trucks.

 Probably wont get this out of my system until I eventually do the experiment.   I know this is Chevy forum, but personally I am pretty well brand agnostic.  I have owned lot GM stuff over years mostly cause it was most available at best price in places I have lived.  Ford seems little cheaper where I live now, so I currently own Ford also I like manual transmission trucks and Ford trucks lot more likely to have a manual transmission.  GM new vehicle buyers truly loved their automatics from 70s on up. Though some here might be interested that when the light duty 5spd grenaded in my Ranger (stupid ford engineers put same dang 5spd they used with the four cylinder behind the 4.0L whereas the 5spd behind the 4.2L in full size was lot heavier duty), I replaced the grenaded five speed with a SM420 granny four speed out of an early 60s Chevy pickup since I already owned this transmission!  And I had the fun of adapting it.  Love mechanical puzzles. Those old granny four speeds were bullet proof, noisy, slow shifting, but bulletproof.  They were originally designed for medium duty trucks so overkill for pickups.  Way Ranger geared I never saw point in an overdrive anyway.  I rarely drive over 60mph.  Driving it now reminds me lot of my favorite old 1960 Chevy Apache 10.   All manufacturers made some good stuff and some that was better to forget.  I have current Ranger where its usable and reliable and check engine light stays off.  So rather not tear it apart to try different drive train.

Offline Irish_Alley

  • Tim
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13299
  • Family is not an important thing. It's everything.
Re: MPG, Part 2
« Reply #102 on: May 17, 2018, 01:48:19 PM »
im sure gearing does play a role in the mpgs but power is also a factor. take my cummins that ive talked about before. with the 350 tbi i was getting 12mpgs now im getting 16 with the same setup behind it (4l80e and 4.10 ratio) in my 91 crew cab v3500. so i got a little over 30% better millage with a different engine that operates in a different rpm range. and the dodge was putting 3.55 behind their cummins for a better mpgs. now the sad part is if you regear or swap motors the price might not ever pay for itself. not sure how much is gained by the OD trans but it might help
If you canít tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Coasting2aStall

  • Newbie
  • Posts: 15
  • Newbie
Re: MPG, Part 2
« Reply #103 on: May 18, 2018, 12:26:03 PM »
I am not familiar with that 305-8 economy truck GM sold in 80s.  Mostly for marketing purposes I am sure and probably not a joy to own in real world.  But I am very familiar with similar 300-6 Ford super economy model also for marketing purposes.  Whatever else they did, Ford put in something like 2.21 gears, it was some insanely high economy ratio that pretty well made truck undrivable considering the power to weight and light duty manual 4spd overdrive.  But they advertised like 30mpg  EPA estimate.  Friend owned one of these.  Literally it would get real world mid 20s mpg which was about as good as the little 4cyl Japanese pickups of the time.  Yea with a carburetor. But just starting off on level ground required major struggle slipping the clutch.  Each and every time. Manual transmission doesnt have the help a torque converter gives an automatic with such high axle ratio. You could smell the clutch lining each and every time.  And unless you lived somewhere that all roads were flat it made you to truly want to avoid driving the thing let alone ever trying to carry a load with it.  Most people quickly decided to put more realistic rear axle gearing in it which promptly lowered fuel mileage to mid to high teens like most half ton pickups.  Or some put in a granny 4spd and started off in granny low.   Overdrive in such a vehicle was a joke.   

If you want overdrive IMHO, then you want something like 4.11 rear or something 3.xx numerically close to that.  Something that lets you start easily but then slows engine down at hiway speeds with overdrive engaged.  Thats whole idea of an overdrive or was traditionally until EPA rules made offering overdrive with 3.27 or higher gears somehow magical.  All it means is an overdrive you can never use in real world.

And yes, my point exactly about spending anything just for few more mpg.  You have to drive a lot miles to pay for it unless 1. you do all labor yourself and 2. parts are cheap, maybe from a you pull it type yard.  And truly makes you wonder about new half ton truck starting out around $30k and I bet most go out the dealer door at much higher price.  If you have that to spend on a vehicle that isnt earning an income, then fuel economy is least of your worries.  I cringe just thinking of the mortgage payments on such a truck.

Like that guy in hotrodders.com thread I gave link.  The one that rebuilt the 327 on his 63 Impala.  He regularly gets over 20mpg with 3.25 rear and M20 4spd (close ratio, not an overdrive).  He said yea there are benefits of fuel injection and overdrives, but you would have to drive lot miles to pay for small gain.  Obviously if he is regularly getting 20+mpg on a 4000 pound car, exactly how much would there be to be gained?  Now on the old Ford he mentions with the 292 Y-block, it has a 2-spd automatic.  He gets 16mpg city or hiway.  On that car no doubt changing transmission would be big benefit.  Those old 2spd automatics, Ford or GM were not terribly economic to drive and I always found them annoying to drive compared to a three speed automatic or manual.  They were meant as a super cheap automatic for the low end of the market I guess.  Personally never understood the attraction of an automatic at all, but most people seemed to love them.  My brain just automatically tells my foot to clutch and my hand to shift a manual without me thinking about it too much.  Is annoying switching vehicles with very different shift patterns.  Back in those days you could, for economy minded, buy a three speed manual with an overdrive.  You pulled out this knob on dash to engage overdrive.  Not that popular though.   Bit like that electric overdrive on 70s era Volvos, which had little switch on top of the shifter knob. That was lot nicer than pulling knob on dash.  I liked those old Volvos but never figured out why they didnt just have a slot for fifth gear in shift pattern.  They did eventually do that sometime in 80s I think.  But not so many people buying a manual transmission by that time.  You could afford a new Volvo, you wanted all the bells and whistles I guess.  Sad for those of us driving them at the end of their life when automatics truly suck cause they can go anytime and cost a fortune to replace.
« Last Edit: May 18, 2018, 12:34:29 PM by Coasting2aStall »

Offline Coasting2aStall

  • Newbie
  • Posts: 15
  • Newbie
Re: MPG, Part 2
« Reply #104 on: May 19, 2018, 12:17:41 PM »
I apologize again for posting non-GM examples.  But this is a fuel mileage thread, and for me old OHV engines with carburetor vs high tech stuff computerized up the wazoo is more important comparison than Ford vs Chevy vs Dodge vs the world.  Like I said I have owned good and bad of several makes and am pretty brand agnostic.

Anyway this is interesting blog page of guy with a 1984 Crown Vic with 302, and running automatic without the overdrive hooked up. http://www.vinny.us/archives/298  He converted it from TBI cause of difficulty around parts for it due to age.  Anyway more important its a 3900 pound car with a 3.08 rear axle.  Sound familiar?  Apparently stock cam and an old Motorcraft/Autolite 2bbl carb off a '79 400-8 engine, which personally I think would run somewhat rich for a 302 but he didnt mention rejetting it. 

But he is getting 22mpg to 24mpg hiway after carb and Chinese aftermarket vacuum advance distributor.  I would say without knowing specs of  the stock cam and such, that this is pure lucky combination.  I had heard of some of the 80s Crown Vic and Lincolns getting pretty good hiway mileage.  But hotrodders seemed to hate these mild 302s, probably good reason to consider such for an economy vehicle.  Its just impossible to find accurate info on factory cam used in these.  You look at parts sellers and they just have generic stock cam that no doubt isnt what was actually stock in these and the generic hot cam they sell to the Mustang crowd.  You can however get a 194/204 at 050 aftermarket Schneider cam.  Or there is a Summit cam for these that is 204/204 at 050 which is close enough.

Ok, here is link to a third party test of the 1984 Crown Vic when it came out. https://www.cars.com/reviews/the-morning-call-and-mcallcoms-view-142068910676 The test car had the towing package with a 3.55 rear axle and got observed mileage of 12mpg in city and 19 on hiway.  So first link with the 3.08 axle sounds correct and not just bragging.  Makes me think this engine in 1984 had a cam much like I pointed out in the pre-pollution cars that got similar mileage.  Wish there was way to know cam specs in that 1984 Crown Vic.  I am just betting when Ford went to TBI, it controlled emissions enough they could use a more mileage efficient cam.  Here is key remark in the review: "rated 134 horsepower at 3,600 rpm and 232 foot pounds of torque at 1,600 rpm"  which says to me they were interested more in good fuel economy than some crazy high horsepower at some crazy high rpm for marketing purposes,  that nobody ever drives at on street.


I was looking at Ford V8s cause its way easier to find a good cheap low mile 302 than a Chevy 305.  Forget finding a cheap used low mile Chev 350.  That ship has sailed.  Ford 351W not nearly as common as the 302 either.  Ford pickup people really like them.  No idea why but the Ford and Chevy straight six engines also getting up there in price if they dont need total rebuild.  Probably just getting rare anymore. Now Chevy 4.3L are very common and pretty cheap even some low mile versions.