chevy 350 good mpg?? 1991 suburban

Can we just all agree that the chevy 350 small block is one *** of an engine. And 86GMCSIERRA about that nova what else do you expect from a chevy then it to run forever.  

Man, that was some pretty good discussion going on.  However I think you both forgot about the 15 year old youngster with the dilemma.  I believe it will be very hard for you to achieve very good mileage with your 91 suburban, especially considering how much that poor mileage actually costs you.  If you do some shopping around I think you could find a quality car for close to the price of 2 tanks of gas that eventually just end up in smoke.  Once you get your mileage and budget in order, then start tweaking on your unit.  I know it is fun to drive a burban around, but at the same time it is not fun to be wasting your money when you know with a little bit of effort you can improve your mileage.  If you are really after mileage try adjusting the nut behind the steering wheel.  You would be amazed how much sensible driving will extend the life of a tank of gas.  Don't be so quick to jump into a major teardown of your engine.  As for the two arguing about small block chevy's,  what are you guys doing?  you have got way too many variables between your driving habits, outside factors and tbi vs carbureted to conclude who should be getting better mileage and why. You both have very capable vehicles for what you are using it for.  Why are you upset about snowman saying he has a good low end torque motor but yours is better. Not necessarily.  a dyno may be showing you that you have so much ft lbs, but how much are you really using with your gear ratio, tire size, weight, etc.  A 240 horse motor that is equipped with the right ratios in the drivetrain will blow the doors off of  a 450 horse motor that uses wrong ratios that can't allow the engine to work.  GET IT?  

Hi guys I have a 91 chevy k1500 with a 350 and a turbo 350 tranny. It is my daily driver and i would like to squeeze the maximum about of mpg out of it. I get about 11 or 12 right now I know I could get more mpgs if I would reduce my tire size back to stock instead of the 33's and take the 3 inch body lift out but you got be able to have some fun in the mud to. I am curious to see if you guys think it would help to swap to 3.73 gears as I am planning to swap in a 700r4 eventually since I do a lot of highway driving and am sick of cruising at 2800 rpms. I am also planning on rebuilding the engine soon since it has 175,000 miles on it and leaks and burns oil and I am an auto tech so I can rebuild it pretty cheap. I would like to get 300 plus horsepower out of it with out sacrificing to much gas mileage. Any ideas? I have already done a throttle body spacer but haven't driven it enough to tell if there is an increase in mileage, but I have noticed a little performance increase.  

Many seem to think that the lower the cruise RPM, the better the MPG but all is not as it seems. Gas SB engines need to turn around 2000 RPM or more at highway speed to be fairly efficient. Force it to to low a RPM can hurt MPG. This is because same HP is required to move the truck and the engine has to work harder at a lower RPM to make this power. Tires and lifts also hurt MPG a lot if you are searching for best possible MPG. Big knobby tires have increased rolling resistance and take more power to overcome and a higher lift adds to drag and power need to cruise. If max MPG is your goal, you want no lift and stock sized (or very near stock) smooth treaded tires at or near max pressure for lowest possible rolling resistance. Higher than 87 octane fuel helps too with SB TBI or VorTec motors.  

HI! I HAD THE SAME PROBLEM,I GOT 11 MPG IF I WAS LUCKY.I HAD A 74,WITH A 72 CAMARO FBM  ENGINE, I PLANED 010 OFF THE HEADS,GOT RID OF THAT STUPID USELESS AIR PUMP,750 QUADRAJET, PUT ON A CARTER 650 AVS 2 INCH DUALS, IT WENT TO 17 CITY 22-25 HIGHWAY!!  HOWEVER IM IN CANADA WHERE YOU CAN CHANGE THINGS.SMALLER TIRES  WILL RAISE NOT LOWER RPM.GOOD LUCK!!!  

YOU DO NOT HAVE ENOUGH SHIMS UNDER YOUR STARTER!!!IT IS A COMMON PROBLEM ON GMS  THAT US DODGE BOYS NEVER HAVE TO DEAL WITH!!!   THE SHIMS ARE ABOUT3 INCHES LONG WITH A HOLR ON EACH END. THERE WILL BE A TAB ON EACH END!! WITHOUT THEM THE ENGINE MAKES A HORRIBLE SCREACH WHEN YOU START IT.. PROBLEM SOLVED!!! TAKE CARE!!!!  

I just filled up my 89 burb. Last time I topped it off was over  3 weeks ago. Since then I drove it 552 miles and 34.9 gallons of gas for a average of about 15.82 MPG About 1/2 mileage was highway driving and about 50 miles of low speed park/sight seeing with a lot of idling too and the rest urban and city driving Last 75 miles or so has been cold weather stop and go driving on short trips with several cold starts. It is a pretty realistic figure given that it was over that time period and usage. 93 octane fuel with timing set at 8BTDC rather than TDC. It has VERY crisp throttle response and take very little throttle to move right out. I will be switching to 89 for winter when it gets and stays cold until it warms up again in spring. When it was newer I was lucky to get 12 MPG in mixed driving with 87 octane and TDC timing. When I taking it to rockies I reset timing to 14 BTDC at about 5000 feet and above and it helps it a lot. With TDC it was a real slug at high altitude on the first trip it made out there when it was fairly new (about 10 months old) I learn my lesson with that vehicie long ago. No 87 or stock timing.  

Sup fellas? I need some help..First off, I have a 98 Tahoe 4x4 35's 350 eng. I wanna rebuild it,but i want power in it what does, any1 recomend? i'm not the best in engine wise but i have an idea so if any1 can help out i would really appreciate it..  

You need some 4.88 gears to turn those 35's more than you need a bigger engine. That VorTec 350 has plenty of spunk if you get the right effective gear ratio behind it. My guess is that you are still running stock gears.  

86GMCSierra:
Oh and on last thing, I drive a 1986 chevy nova everyday, it gets 45mpg. I have driven it everyday, through blizzards and 100 degree weather, the car has never failed to start and runs like a top. It cost me $500 3 years ago and all I have done to it is change fluids, plugs, cap, rotor, and a new set of $15ea. tires, I have even hauled complete small blocks in the trunk. With the money I save by driving the car I can afford to Use the truck for fun and not have to worry about bad gas mileage. So for much less than $1000 I have a reliable car that gets 45mpg, runs great, and will last for many more years. That kinda puts your 18mpg to shame, huh? Again, my truck runs a real mild 350, .030 overbore, flat top pistons, 202 camelback heads, stock intake, mild rv cam, and stock rams horn exhaust manifolds from a 60's 327 with single 2 3/4" exhaust, no cat and a turbo muffler the truck is extremely quiet(I like to be quiet and polite on the trails), smooth running and very sturdy and reliable, when I need my fix of outrageous and abnoxious power I drive my high 10sec. '78 malibu.

202 heads and a stock intake and exhaust??

what is the cast # on your heads? and cam duration and lift.

don't tell me you don't know, I may tend to go along with the snoman calling you a story teller.  
---------------------------

see me at robsoffroad.com

I know this forum is really geared towards trucks but im having a problem with my car and everyone here seems to be very knowledgable.   I recently bought a 1984 camaro with a rebuilt 350 and th400 trans.  Its got an edelbrock carb and headers.   Its a pretty much stock engine.   Im experiencing a rough idle... when im in drive i tend to stay at around 1k rpm, but in park sometimes ill be at 1500 or even up to 2000 rpms. My exhaust smells very strong and is leaving out black residue. Im also stalling a lot.  What are some solutions i should check?  

I think you should start with looking for vacuum leaks and check manifold vacuum at idle. There could be a lot of things wrong but this is a good starting point.  

35" street tires @65 to 80 psi with load range e tires,real skinny tires rule to get mpg.  

The manifold vacuum seems fine at idle. I played with the carb a little and got it to idle a bit better in park.. Around 1400-1500 even sometimes staying around 1300.  But now my issue is when im actually driving the car its fine for the most part unless i open up on the throttle, then i stall.  I smell a very strong smell of gas when i open up (keep in mind my vents are not sealed yet as i dont have AC or heat installed) and then the engine stalls.  Sometimes i can start it back up but not usually which is making me believe its flooding..  but i definitely dont have it set to run that rich.  

How do you define fine??? have you taken a actual reading and if so what is it? Carbs are very sensitive to vacuum when setting mixtures. Also when it dies does it ever tend to backfire through carb as it dies?