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#1 |
Registered User
Join Date: Jan 2002
Location: Springville, UT, USA
Posts: 1,010
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4.3 in 71 getting 19 MPG?!?!?
OK....my friend put in a 1989 4.3 with a stock throttle body into his 71 LWB truck and he says he's now getting over 19 MPG on the HWY. Is he lying?! He said he also has great power. He also bolted over the 700r4 tranny as well. The engine is stock except for the headers. Has anyone else done this and has had good luck with gas milage? I'm thinking of putting in my 4.3 engine from my 88 astro into the truck. The engine and tranny were rebuilt just 3 years ago.
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#2 |
Registered User
Join Date: Feb 2005
Location: Bay Area, California
Posts: 995
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Re: 4.3 in 71 getting 19 MPG?!?!?
I guess anything is possible... Is the 4.3 a v6?
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1971 Chevy C10 Shortbed Stepside, 307v8 3-on-the-tree |
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#3 |
Where's my beer?
Join Date: Oct 2004
Location: Glen Allen, VA
Posts: 1,770
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Re: 4.3 in 71 getting 19 MPG?!?!?
I don't doubt that for highway only mileage. I'd say to see how good the 4.3 in your Astro does and I would assume the truck would be about the same. I would say it probably has acceptable power especially if you're used to v8's but I wouldn't say it has great power. then again, why dont' you just ride or drive in your buddies truck and see for yourself.
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70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam. 79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam. '03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great '08 Tahoe LTZ 4x4 155K |
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#4 |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: 4.3 in 71 getting 19 MPG?!?!?
There was a member here (scooter67) that had a newer fuel injected V6 in his 67 truck and he claimed to get 22-23 mpg highway, which is totally believable because new silverados with the 4.6 are listed at 16/21 for the automatic. You take away all the smog crap and catalytic converter and 23mpg is totally possible. With no fuel injection 19-20 seems about right.
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! |
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#5 |
Registered User
Join Date: Mar 2005
Location: minnesota
Posts: 78
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Re: 4.3 in 71 getting 19 MPG?!?!?
Also the ?92-93 - somewhere in there 4.3 motors were the beginning of the vortec technology later implimented in the 5.7's in '96, so if you get one from that year range they've got more HP/TQ than earlier years without much (if any) change in mileage.
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#6 | |
State of Confusion!
![]() ![]() Join Date: Jul 2002
Location: Gulfport, MS USA
Posts: 46,901
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Re: 4.3 in 71 getting 19 MPG?!?!?
Quote:
A friend of mine around same time had one in an extended cab with automatic and loved it. But he most just haul a-- and what ever game he shot. If I was looking for a different daily driver I would look at a SWB with one. To me they are a great balance for everyday use and the occassional I need a big trunk or truck thing.
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! Last edited by Palf70Step; 10-20-2005 at 09:39 PM. |
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#7 |
Registered User
Join Date: Dec 2003
Location: gilbertsville,KY
Posts: 111
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Re: 4.3 in 71 getting 19 MPG?!?!?
believe it or not but i went to Miami over the weekend with my 04 Z71. I was getting average 23MPG
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1992 Jeep Cherokee 4.0 AUTO 1972 C10 350/350 1971 C1500 350/350 1970 C20 396/400 |
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#8 |
Nothings as cool as my 72
Join Date: May 2005
Location: Edmonton, AB, Kanuckastan
Posts: 181
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Re: 4.3 in 71 getting 19 MPG?!?!?
My dad had a 97 extened cab shortbox with a 4.3 and a 5 speed that got like 26 on the high. I think the truck had 3:73 gears in it. It's even towed a 5000lb. 30 foot long trailer. He ended up selling the truck to my cousin who ruined it by putting more leafs in the back, taking offroading and damaging it, now he wants to put a locker diff in it. now the truck sits at my cousins place because he bought a cocge and doesn't use the chevy anymore. If he din't wreck it my dad would probably buy it back and I could drive it while my truck is being built, It was a good truck though.
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1972 C10 Longbox In the middle of body off restoration Rebuilt 355, turbo 400, 3.42 12-bolt Rolling chassis finally done and cab mounted. Now onto sanding, bondo and more sanding. ![]() |
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#9 |
Registered User
![]() Join Date: Feb 2001
Location: East Central, MO
Posts: 11,336
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Re: 4.3 in 71 getting 19 MPG?!?!?
I have a ZR2 with a 4.3 auto. The very best it will do on the highway is about 17mpg.
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#10 | |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: 4.3 in 71 getting 19 MPG?!?!?
Quote:
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! Last edited by 67ChevyRedneck; 10-20-2005 at 03:21 PM. |
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#11 |
Registered User
Join Date: Jun 2005
Location: Sacramento CA
Posts: 1,255
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Re: 4.3 in 71 getting 19 MPG?!?!?
IMO 4.3L engines get better gas mileage with manual transmissions vs automatics. I have one in a 1993 S10 4L60E and it gets 20-22 on the freeway with cruise control. Around town or mixed driving, the lock up TC seems to suck the gas mileage out of my truck. It trys locking up at 40 MPH which is a common driving speed. My 4.3L TBI is not big on low end power. Headers might help.
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Got bored, sold everthing. Got bored, looking for a 1960-66 C-10. Want to build my last truck. |
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#12 |
fugedaboutit
![]() Join Date: Mar 2005
Location: Gresham, OR
Posts: 832
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Re: 4.3 in 71 getting 19 MPG?!?!?
My 98 zr2 is right around 17 too..
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Currently truckless ![]() |
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#13 |
Registered User
Join Date: Jun 2001
Location: Austin, Texas
Posts: 796
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Re: 4.3 in 71 getting 19 MPG?!?!?
I'm getting 18.5 highway mpg with this combo in a 69 SWB with AC on.
I do have a vacuum gauge that I try to keep above 10 mm hg 1800RPM at 70 mph 3.08's and 28 inch tire. 70 series tires. Trans 700R4 with lockup converter Engine specs. 1995 GM 305 crate motor with Edelbrock SP2P intake, 1976 800CFM BOP Q-jet with 2 inch 4 hole spacer, 1 5/8 full length headers, recurved HEI with MSD6A. Has thermo fan clutch. 195 F thermostat. Set up for lowend torque and to run on 89 octane. Truck is lowered
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69 SWB C/10 5-6 drop 700R4 69 Firebird Convert 455 4 spd 70 Torino GT Convert Austin-Texas |
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#14 |
The LuvShack Garage
Join Date: Jan 2004
Location: Maple Grove, TN (West Side)
Posts: 30,477
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Re: 4.3 in 71 getting 19 MPG?!?!?
Wife's 99 trailblazer gets 18 C / 21 H and it's a 4dr 4wd
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Owner/Op: "TN Classic Transport Carriers" The Toy: "Square Vette" 72 Hybrid Blazer Toy Barn: "LuvShack" 40 x 60 x 20 Shop Tow Piggy:"Maddy" 88 Silverado 3500 Hauler: "Feathers" 14 Aluma 8218T |
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#15 | |
Registered User
Join Date: Jan 2005
Location: Colorado Springs
Posts: 693
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Re: 4.3 in 71 getting 19 MPG?!?!?
Quote:
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1971 GMC K1500 SWB Fleetside, 4" skyjacker softride and, 14 Bolt FF, HD Dana 44 4.10's 1970 K5 TBI conversion lifted etc SOLD 1968 C20 camper truck SOLD “To ban guns because criminals use them is to tell the innocent and law-abiding that their rights and liberties depend not on their own conduct, but on the conduct of the guilty and the lawless.” Jeff Snyder |
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#16 |
Registered User
Join Date: Apr 2003
Location: Central PA....In the Berg of Nisbet
Posts: 790
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Re: 4.3 in 71 getting 19 MPG?!?!?
You want awesome mileage drop a small Diesel in it.................It will blow the 4.3 away preformance wise and do alot better fuel mileage wise.
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'72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!! |
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#17 |
huh?
![]() Join Date: May 2000
Location: Washington, Illinois
Posts: 5,692
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Re: 4.3 in 71 getting 19 MPG?!?!?
My friend has a 96-ish swb ext cab C1500. It's got a 4.3/5spd, and he pulls down an honest 25 MPG all day long. Blew me away.
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Someday when I'm lonely, Wishing you weren't so far away, Then I will remember Things we said today. RIP El Jay |
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#18 |
I'm watching you!
Join Date: Feb 2005
Location: Levittown, PA
Posts: 1,822
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Re: 4.3 in 71 getting 19 MPG?!?!?
I think it depends on how you drive it. My dad's 93 4.3l 4l60E (which I think was the first year for the vortec, listed on the window sticker as vortec) is good on gas when you baby it. I drove it like I stole it and gas milage sucked. Highway if you push it over 65 forget about milage...pushing a brick with that engine over 65 makes it thirsty. I think it would be better on gas with the 5 speed.
Mike
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2012 Chevrolet Silverado 1500 Z71 4WD 1993 Chevrolet C-1500 W/T - Blue - 4.3L V-6, 4 speed auto - Dad's (RIP) 1992 Chevrolet S10 - LS swap project 1968 Chevrolet C-10 longbed fleetside - sold ![]() |
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#19 |
Registered User
Join Date: Jan 2002
Location: Springville, UT, USA
Posts: 1,010
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Re: 4.3 in 71 getting 19 MPG?!?!?
wow.....what great insite you guys have given me....and none of it negative!!!!.......I guess I know what I have to do.......She's going in!!!!!!.....After winter.
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#20 |
Senior Member
Join Date: May 2002
Location: NORTHEAST OHIO
Posts: 493
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Re: 4.3 in 71 getting 19 MPG?!?!?
I've got a neighbor who is 87 yrs.young,really a pretty cool guy who has seen a lot and done a lot in his life and still doin neat stuff,called me tonite lookin for a hydraulic fitting for a log splitter he's making...anyway,he told me once and I never forgot it that "even the most honest people in the world will fib about two things,gas mileage and how long it takes them to get somewhere"
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#21 |
Senior Member
Join Date: Oct 2004
Location: calhoun city ms
Posts: 940
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Re: 4.3 in 71 getting 19 MPG?!?!?
I have a 7.3 turbo diesel international that will get 22 on a highway run as long as it is not loaded, just the truck and this is with 3.73 gears and a 6 speed manual with overdrive.
Actually, the 4.3 in that truck should top 20 mpg if driven right. My 94 z 28 will get 25-27 on highway if driven like an economy car.
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ongoing 1970 c 10 lwb ![]() 1994 z-28 few mods.-owned since new ![]() 1978 vette silver/grey 25th anniv. paint ![]() |
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#22 |
Registered User
Join Date: Jan 2002
Location: Springville, UT, USA
Posts: 1,010
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Re: 4.3 in 71 getting 19 MPG?!?!?
now here is a funny question.....why doesn't GM have the 4.3 as an option for the Colorado?
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#23 |
I'm watching you!
Join Date: Feb 2005
Location: Levittown, PA
Posts: 1,822
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Re: 4.3 in 71 getting 19 MPG?!?!?
I think they are trying to phase out that motor. The plan is probably to put the inlines in the new gen trucks. Thats just my guess.
Mike
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2012 Chevrolet Silverado 1500 Z71 4WD 1993 Chevrolet C-1500 W/T - Blue - 4.3L V-6, 4 speed auto - Dad's (RIP) 1992 Chevrolet S10 - LS swap project 1968 Chevrolet C-10 longbed fleetside - sold ![]() |
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#24 | |
Registered User
Join Date: Dec 2004
Location: Northern AZ
Posts: 7,271
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Re: 4.3 in 71 getting 19 MPG?!?!?
Quote:
Yeah, the Coloradoes and trailblazers get either the in 6 or the small V8. I have an 05 Yukon XL (Suburban with the 5.3 and I pull 20-21 on the highway, so that kind of milage out of a V6 is believable. Do the swap you have all you need and it is easy as dropping in a V8. Let us know, the V6 is kinda like the plague at bone yards so they ought to be cheap!! I personally wouldn't put anything under a 350 in my truck, but a $3= a gallon a V6 is looking beteer and better. |
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#25 |
Registered User
Join Date: Apr 2005
Posts: 56
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Re: 4.3 in 71 getting 19 MPG?!?!?
I had a 2003 ZR2 and it was consistently getting 16-17 miles to the gallon on the highway. Pulled a 2800 pound enclosed trailer once and got 9.5 mpg. The next week I traded it in for a 2003 GMC Sierra 5.3 litre 2wd and it is getting 18-19 on the highway and around 14 pulling the trailer. Yes I gave up 4x4 but I have a lot more power and room now with the full size. Plus with a 6 month old kid there is a lot more room in the extended cab of the full size then the ZR2.
My wifes 2004 trailblazer 4x4 is only getting 15-16 mpg in the city and have taken it on one small trip that was 75% highway and we only got 17 mpg. It is supposed to get 16 city and 21 highway. It has the 4.2 litre inline 6. I am not happy with the gas mileage at all.
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2003 GMC Sierra 1500 (Camper and Dirtbike Trailer Hauler) 2004 Chevy Trailblazer (Wife's Daily Driver) 1983 Chevy 3/4 ton 4x4 350/TH400 (Sold) 1993 Buick Century (My Daily Driver) |
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