I was wondering if anyone has a carbed car that gets good gas mileage, 20+. If so, tell us your set-up. What you did to improve mileage, tuning kit, rebuild, etc. I know most people who have carbed cars dont care about fuel mileage. I'm trying to break the 18 MPG barrier so that my 87 TA can be a daily driver, 40 mile commute.

85 TA, 35 mile commute each way mixed 35/interstate. Average between 22 and 24 even with AC. Normal tune up stuff, well maintained, nothing special.

Did see an increase after going to electric fan but an 87 should already have one.

Got low twentys (same commute) in my 87 Camaro with a 350 w/vortec heads but that was before a cam change. Now I'm in the 19-20 range.

My 89 has a l98 350 with phase2 aluminum heads with mild cam and bored. Running a 750 carb and 3.08 factory rebuild rear. I get around 20+ on highway. Also with t-5

I went on a trip a couple a weeks ago and gased up right before getting on the freeway and again after I got to my destination it was 200 mile trip all highway 65-75 mph and I got 24 mpg.

Vortec headed 350.
XR276HR cam.
670 Holley/RPM Air Gap.
700R4
3.70 gear
23 mpg coming home from the track last summer. 200 miles of mostly highway at 75mph.

355ci, with 284H cam. 11;1 TRw forged pistons and forged bottom end. 74cc heads, so compression isnt too high. Heads ported, but nothing major. RPM air gap intake manifold, and 750 holley DP with 4 corner idle, mech secondaries. 1 5/8 headers (shorty), 3 inch Y pipe terribly made, with 2.5 in cat back exhaust into a 1 in 2 out dynomax super turbo muffler (the quietest one).

With this combo i got only 15mpg or so, with 100% bumper to bumper traffic in the middle of summer.

Before this setup i had a q_jet and factory aluminum 70's intake manifold (the rest was the same). The 80's q'jet was set to max float level, but because of the jets it still ran lean. In any case, this combo gave me 17-19 mpg, in 100% bumper to bumper, in the middle of summer.

Highway and rush hour mixed, gave me 22-23mpg.

After i put the holley 750 and rpm air gap, i also got a t56 with a 0.5 6th gear. On the highway with my 3.42 rear gear, and 235/60/14 tire, i got almost 34mpg. (33.***) dnt remember the decimal. This was 100% highway.

I havent driven the car enough with this combo to get city. But 100% city driving is probably somehwere between 14-16, and mix would be above 20.

20+ mpg would need different combos depending on what sort of a route your 40 mile trip is. But you cant go wrong with a leaned out Q-jet.

My 85 LG4 was particularly sensitive to timing. I ran advanced timing, around 4-6 degrees for several tanks a while ago and experienced a noticeable drop in mileage. Assumed the motor pinging and the KS was pulling timing. Set it back to zero and was back to my 22-24.

I get low 20's on the highway with my combo. But in the city it's only about 14 (converter hurts a mpg or two).

i got 26 mpg highway back when my car was bone stock, 305 with 5-speed. don't underestimate q-jets, they can get good mileage properly tuned

L69 with good tune and rebuilt QJet, 3.73 gears, 5 speed, Headers etc...I get about 14 mpg....

of course, your driving habits are one of the biggest factors...

With my '84 T/A during the summer time I have averaged city/hwy 23MPG on a tank of gas but most of the time its around 18-20MPG. Its a LG4/TH700R4 auto with a rebuilt carb and DynoMax cat back exhaust and a 3.23 rear axle ratio.

All stock 85 Camaro low-output LG4 305 in good tune with 5 speed trans and 2.73 rear gears. 26 MPGs on long highway trips. But about half that in town.

That's great to hear. I guess I need to get it ready for the summer. Thanks!

This is totally true. While on the highway, I average 26-28 m.p.g. and on the street anywhere between 14-17 m.p.g.

Now...when I really open the car up, street becomes 9 m.p.g. or less and highway down to the 16-18 range. Camaro's tend to be peculiar on mileage.

perhap a 390cfm hp holley would work great for mpg, but i didnt get anywhere 20mpg from my carb.
more like 10mpg along with 425rwhp

you guys give me hope lol. im currently switching to carb with a 305 and stock 2.73 open diff. unfortunately the engine is as dirty as the floor of my garage hope that wont hurt it to much. last owner rarely changed oil and the engine is full of gunk. but im not going to rebuild a 305, id rather save and buy a used 383 and rebuild it.

A can of engine degreaser used with the spray wand at the local car wash will help with the exterior engine gunk. A quart of ATF mixed into the engine oil a hundred miles or so before an oil change will help with the interior engine gunk.

I believe 24 was the best I ever got from my LG4 with 700r4 and 3.08 gears, before I removed the CC carb and distributor. But, my average was about 18-19. Without the CC carb (still a q-jet, just a different one) and distributor, and timing set at 8*, I never did recalculate my gas mileage, but it seems to be about the same.
The engine in my car was poorly maintained until I got it, and even has a knock now, and has 186,000 miles, so you should be able to have the same mpg I was able to get, but probably better.

I was gonna say I've only seen 16mpg on mine, but this makes sense. I've got 6deg advance for performance. 0deg advanced got me passed emissions. Now I wish I had kept my adjustable timing box.

I'm running a Goodwrench 350 (4 bolt, cast crank and slugs) with World Product S/R Torquer cast iron heads (2.02/160, 170cc intake runners, 67cc c/c), Comp Cams roller tip 1.6 rockers with Crane kool nuts, Crane chromemoly pushrods, Edelbrock Performer EGR intake, the stock Q-Jet (Rebuilt and Slightly Modified by me), Accel Billitech Distributor, Accel coil, MSD 6A, MSD 8.8 wires, Lunatti 06103 cam and lifters (.442/471@1.6 204/214@.050) Edelbrock double roller timing chain, Melling HV55 oil pump, Carter 80gph fuel pump, Edelbrock tubular exhaust, Dynomax ultraflow catback and AC Delco rt44 plugs. Stock 700 tranny, and stock 9 bolt with 2:77. Car runs great, (no check engine (Carbs and pumps) light unless there is a problem) all 100% legal and gets 24mpg highway at 70 on cruise with a/c on. Installed in 87 Formula.

Carbed lg4 in my 86 camaro made 22 mpg on the highway and pure crap in the city.

Setup...

Stock heads cam

headman shorties

Stock vacuum distributor (can get one from autozone just look up the canadian camaro) Best highway driving was around 6-8* btdc hooked into manifold vac and street around 8-9* hooked into ported vac.

Performer EPS intake manifold 2701
1405 carb

700r4 tranny with more than it's fair share of miles on it.
2.73 rear

every possible emmissions component you can think of yanked out. computer not even powered anymore.
TV cable disconnected and shoved into its minimum state and shift it manually.

and ran it on piss poor gas.


and even after the rear end was swapped out for a 3.42, it still pulled off around 18-20mpg.

It's really all in the tuning and how you drive it though. For highway figure out what your most common rpm range will be and tune to make power there. The other ends will suffer and usually city driving takes a major hit but long hauls pan out pretty good. Put nearly 1300 miles on mine for my last road trip and stopped for gas 5 times total. (couldnt resist getting it wide open on the empty stretches.)

You can't expect a system to work properly when it has been improperly modified. You don't put a vacuum advance distributor with a computer controlled carburetor.

I didn't do much highway driving with my stock LG4, but my one road trip yielded 26 MPG average on about 750 miles round trip - my TCC lock-up didn't work at the time. My nephew had an '86 Berlinetta with stock LG4 that would get him around 27 MPH highway.

With the current 350 configuration I typically get around 16 MPG commuting, about 22-23 MPG highway (again, not many highway trips - 100 mile round trip to the airport, mainly) burning high altitude regular unleaded.

Was just giving the mileage with what I had in there at the time. Alot of the engine has been changed up now lol. Completely agree 100% if it isn't broke don't 'fix' it.

The old distributor wasn't working because the ecm was fried and it wasnt adjusting the curve at all. Hence the vacuum distrib. I picked it up cause it was cheap. The engine ran good just wasnt economical in both driving conditions but could be tuned for either. It was the poor mans way out of a jam lol. Got an accel distributor in there now.

back in the day when my 86 was on the road i was getting around 18-21 range with mostly around town and some highway. it was a stock lg4 700r4 and 2.73gears all with around 210k on them. i was also in highschool and was low on funds so i was easy on it as not to break anything. got around 16-17 in my 82 in town with .030 over 305 shaved 416 heads summit 1103 cam 1.6rr hedman lt's true duals 1406 carb rpm intake 79 chevy pickup vac advance dizzy th350 with 2800 stall(more like 2200) and 3.42's.

I have an 85 TA with a 305, bone stock except a new muffler, with a carb that needs to be tuned a bit, but... gets 15 city and about 24-25 highway. perfect for me.

To jump on the bandwagon...

Back in '95, drove my 86 Z (pretty much stock back then) from Blacksburg, VA to Dallas, TX and back, got 30 mpg. That's the best I ever got from her.

On average, I'd expect low 20's for all around driving.

A couple years ago on a trip I fueled up in the morning and went right to the inter-state. I drove at highway speed keeping up with traffic, OK I passed a lot of cars, without stopping until down to 1/4 tank. Stopped at first station and checked my mileage. Was surprised to see 29 mpg. I thought I screwed something up and got back on the Inter-state. The day was warming up so the a/c went on. Same driving style and next check showed 28 mpg. The car is an '85 IROC with L69, t-5 and 3.27 posi. rear gear. Mileage around town sucks but that could be my fault, that 5-speed is just too much fun.

You've installed a 9-bolt 3.27??? Otherwise, it would be 3.73....

You are right! I swapped out the 3.73 for a 9 bolt with 3.27 gears. When I did, my cruising speed rpm's dropped about 500. the car is a highway cruiser so I haven't missed the low gear bite.

man u guys are all lucky getting almost or more than 20mpg....i have a 350 stock other than intake, headers..... its an 82 so no overdrive 3.23 gears... i get about 7-9 mpg taking it easy in town and 11 highway at 55mph.

i shouldnt be getting such horid gas mileage but idk its been that bad the whole time ive owned the car.

I'm amazed at the problems with mileage that some of you live with rather than working on. An '87 Trans Am means a TPI V8, and an overdrive trans. NO excuse for less than 23 mpg at 65 mph. Start with the exhaust oxygen sensor. An '82 with a stock 350, except intake and headers, with 3.23:1 and no OD, should be 13+ mpg all the time, and 16 mpg highway. Guys, fixing the problem costs less than getting poor mileage. Please PM me if you're nowhere near where you should be. I will need more details than most of you are including in your posts. What exactly do you have, and what exactly have you tried, or decided to not try, and why.

Agree with the intent except there was no 350 stock in 82 and an 87 TA could be had with a carbureted 305.

Okay, I was mistaken about carbureted 305 in '87 T/A, shoulda realized that from the OP posting in this forum. I knew perfectly well the 350 wasn't offered, but he claims his swapped-in 350 is essentially stock, except intake and headers. So you misunderstood there. But he PM'ed me, and we'll get that 350 doing better.

Argghh. Didn't mean to come across as one of THOSE nitpicky guys. Sorry.

And yes, it's amazing sometimes how little effort is required to get one of these back running right. Usually a few tankfuls in $ for new plugs, wires, cap, rotor and maybe an O2 along with a little time setting the timing.

My personal favorite mileage/performance quick fix is resetting the baro sensor mod:

owner: "my car runs like dog crap"

me: "why's there a vacuum line connected to your baro sensor?"

owner: "looked like it was supposed to be there"

Caught that one more than once.

I apologize too. I was really tired at that moment.

yeah but the quadrdo jets are a bitch to take a part and put back together with out much prior knowledge

if nobody has put it before get a hydrogen kit :P or what ever its called i will giver you 15+ mpg

Not as bad as the first carb I took apart and put together. All you have to do is follow the directions in the kit, which is a numbered exploded diagram.

FWIW, I took the Camaro on a rare road trip this week. 75 MPH interstate, fought a stiff side wind for most of the drive, tail wind for about 100 miles, straight head wind for 20 miles, a couple of "aggressive" low-elevation "acceleration tests", 22 mpg average. We'll see how it does on the trip home tomorrow.

Mythbusters tested the hydrogen thing. The kit didn't help the carbureted car. In fact, they had to run a big hose from a couple-hundred-pound cylinder of hydrogen to make it useful.

My last tank of 87 oct was 17.25 MPG to work and back on basically a stock set up.

I installed a vacuuum gauge and it shows steady per specs (15 @ 2,000 rpm). Plenty of in town up & go if stomping but then MGP will go down to ~14.5 MPG. A while back before gas was 10% alcohol, I routinely got 16-18 MGP in town, so finally getting near that range is sweet!

For me it took a good tune-up & carb adjustment, using an excellent motor oil, setting timing to ~6* BTDC, and when accelerating watch the vacuuum gague and don't go much lower than 10 or 11.

Ok, so just to make sure I'm calculating it right, the stock gas tank in third gens is 16 gallons? If so, I have to convert my trip odometer from km's to miles and then divide that number by 16 right? If thats right, then I'm getting 11 mpg's with 40/60 highway/city driving! Damn! What kind of trip distances do you guys see from a full tank?

Since your canadian this is how you do it.

1. Fill your tank, and reset trip odometer (or remember odometer reading)
2. Drive for whatever distance (at least 50k)
3. Fill your tank again
4. Take your km travelled and divide by 1.6 (to make it miles)
5. Take the liters you just purchased and divide by 3.8 (to make gallons)
6. Divide Miles by gallons
7. Thats your MPG.

I find that in my carb'd LG4 gas mileage has lots to do with temperature. Every morning i either drive about 10-15 minutes, or drive half an hour on the freeway to school. On the colder mornings, especially when im just going 10-15 mins i get horrible mpg, liek 12-14ish. But if i take the freeway and city (50/50) i get abotu 23-25mpg.

This is why i think an electric fan would be such an ideal upgrade for me both fuel economy and power wise, quicker warm up time then clutch fan, and less power wasted.

Edit: I also forgot to include, that ive gone on quite a few roadtrips in my car. Well... 4 of them. On all of them i got between 28-31mpg (mostly highway), with alot of passing, mountain climbing, "acceleration tests", 3 people and their luggage, and even t-topless cruising.

10-12 mpg on a good trip... ...

I got 24 in my car on the open road and not driving the snot out of the car. Just cruising at 70 mph with 3.08 rear gears and 5 speed T-5.

I was driving back from PA when I first bought the car and was getting almost as good of gas mileage as my little cavalier. In town it was around 16 which was still respectable.

I'm going to say it now and don't tell me im lying and what not but here was my setup:
350 bored .060 over
milled heads
dome pistons
Tunnel ram with 2 600cfm holleys VS
edelbrock performer cam
3.08 open rear
T-5
93 octane
Light foot

And that is it.

Original Set up, Stock L69 with Qjet, Hooker 2055's and a flowmaster muffler. 700R4 and 3.73 factory gears.

I took three trips from New Mexico to Minnesota, over 900 miles one way and I averaged 23mpg on with the cruise on at 70mph.

Around town I would get about 15-19 with a combined of 20-21ish

Since the engine swap before I started having my issues...

350 bored .040
World Sportman II heads
Edlebrock Performer Intake
Hooker 2055's
Custom 3" exhaust

I was getting 15 MPG highway but I'm pretty sure I had tune issues...I'm thinking I should be able to get 20 highway out of this thing.

Mines not measured in numbers, but in symbols.... &*$#@#$&@&!!

Best I've managed was 24 freeway, and that was with the timing too far advanced. The weather seems to be what varies my mileage. I can take it easy or rail it at every stoplight; it may only vary less than a mile per gallon. In the summer I manage 18 city. Mine's pretty much stock; LG4, 700R4, 3.08s. Open element and no cat. This was going out to PA from MI last summer. coming back I was bringing one of the girls from my church back with me, and hauling her luggage knocked a couple mpgs out, lol!

I'm curious; all those getting close to 30, would this be due to 2.73 rear gears? If so, I would consider swapping to 2.73s for a short time, just so I could laugh at getting better mileage than my dad's civic!

its been over a year since the OP posted this thread, but ill add one more carb'd engine with decent milage, with my new qjet i get around 22-25 on the highway, probably around 15 or so in the city

I'm curious; all those getting close to 30, would this be due to 2.73 rear gears? If so, I would consider swapping to 2.73s for a short time, just so I could laugh at getting better mileage than my dad's civic![/quote]


3.27s in mine. T-5 transmission with .63 5th.