Better Gas Mileage Ideas for Classic Chevy

[tsetsaf]

Greetings to all and great forum. I am new here as I just inherited by Grandfather's 1971 C-20 Custom Camper 350/ 350. I will be creating a build thread in the coming weeks as I begin the restoration.

I am located in Southern California where Regular gas is currently running at $3.33 a gallon and this truck will be my daily driver.

I am interested to hear about the following:

• Tricks you use to increase economy
• Gear and Transmission Setups for Highway Cruising
• Methods for dropping weight without compromising strength/ durability
• Finally, average mpg you are achieving in your classic Chevy

I am already planning to swap the 350 trans for a 700R4 but am open to any suggestions on further (and cost effective) ideas to tame the beast.

Thanks in advance,
Mark

P.S. For reference sake I found this thread http://www.67-72chevytrucks.com/vboa...p/t-28315.html but want to get up to date ideas and a more realistic assessment of what YOU have done.

[BigDaddyDave]

Welcome to the board from NC.

[70cst]

tsetsaf ...you will soon have many responses to your questions. There are those on this site that have much more knowledge than I to answer your questions. Good luck of your new project.

[Zonaman]

There's always fuel injection. Be sure your tires have good rolling resitance. There's lighter motor oil weights but your bearings might not like that. Also electric cooling fans, and the wamest thermostat you can manage. Dirve with your eye on a vacuum gauge too.

The best I'ver ever managed, with my carbureted engine, is 14 mpg, highway. I'm usually around 11-12 city. Towing the boat- Let's put it this way: I invest in oil futures just prior to going on a fishing trip!

[67ChevyRedneck]

A Th350 with a 3.08 gear will do almost as well as a 700R4 with a 3.73 and save you a couple grand as well.

I have a carburated 350 with a 700R4 and 3.73 and get 12.5-13 city and 15-16 highway. It's about the best these aerodynamic bricks can do.

If you want to spend some big money, a 5.3L/4l60/with a 3.42 rear end will probably get you 14 city and 18-19 highway.

I think the best option is a small diesel with a 5 or 6 speed. I could see that easily pushing one of these trucks into the 20's. But again, very costly???

[Jim_PA]

Stick with a q-jet, 3.73's with that 700R (maybe 4.11 if you go with a 30"+ tire), and build for low-mid torque. Should be able to do as good as a new one.

[Zonaman]

Originally Posted by Jim_PA

Stick with a q-jet, 3.73's with that 700R (maybe 4.11 if you go with a 30"+ tire), and build for low-mid torque. Should be able to do as good as a new one.

I get a sense that the q-jet is preferred over the Edelbrocks (i.e. 1406) for fuel economy. Would you agree?

[68caliRat]

Welcome "fastest" I have no good answers for you but these guys and gals, should come through for you..

[TotalChevy1]

the options are unlimited, it just depends on how much you want to spend. Check out the cheap electric fan thread and get rid of the clutch fan, living is south calf that thing will kill your mileage. the lower you can get the RPM's the better.

[piecesparts]

Everyone has ideas. All centering around the thoughts, but not actually saying the fact of what you should do. Look at what you need to achieve for RPMs as you drive. Is your driving in the city or highway for the majority and then align your gearing and engine to that. I have found on my trucks that the GM SBC likes the RPMs around 2000 to 2500 for overall efficiency. That can be done with many different tire, gear, and tranny combinations. Look for a good fuel system (carb/air filter or fuel injection) and exhaust system for the efficiency of engine operation. The use of "Fuel Injection" has enhanced mileage over the standard carb. However, there are shops in Los Angeles, that have done articles in the car and truck magazines that state they can get fuel injection mileage out of a decent carb. Look at the use of items to remove "Power Robbing" things from the engine. Electric fans on my trucks resulted in a definite MPG gain, getting rid of the engine driven fan is a good idea.

The use of a warm T/stat is NOT always the answer. Using one to get the most optimum air/fuel ratio is what is desired. I actually run a 180 degree T/stat on my daily driver 91 Silverado with a TBI unit and I get 20 MPG. I get 15 MPG with my 84 GMC and a 400+ HP, 383 stroker motor and a 700 R4 tranny, along with 3.73 gears. Don't think that the gear ratios that are higher will always get you better mileage. When we put a 700 R4 tranny in my son's truck with a 3.08 geared rear end we LOST mileage. The transtion to a 3.73 geared set raised the mileage 3 MPG. ONCE again ---shoot for an optimum RPM and gear/tire combination.

[ChevLoRay]

Welcome to the Board from the Heart of Arkansas, or Ar-Kansas if you believe the coach at LSU....whoever he is.

Improving fuel economy is of interest to all of us, whether we are in Socal, or New England. The same things that apply to a Honda, are applicable to our trucks.

Lightening them up is best done by not hauling anything that you don't need to haul, like stuff in the bed. Tire pressure is important, but I'm running wider-than-stock tires, which have more roll resistance than the stock skinny tires these came with. Disc brakes can have a residual amount of pressure on the rotor, causing a little bit of rolling resistance. Drum brakes can be adjusted to eliminate any rolling resistance, but at the price of having brakes that may need to be pumped to gain stopping power. Final drive ratio is key to engine RPM at highway speed. While our newer stuff frequently runs in the 21-2400RPM range at 70MPH, these trucks will run at higher RPM's because the final drive is what it is AND they do not come with OD transmissions (like a 700R4, or a 4L60E, etc.). If it is a manual gearbox and has a factory overdrive, consider yourself lucky.

But when you have it blown apart for the restoration, consider having all of the body panels acid-dipped to shave some pounds of of the body. I woudn't do it, but it may be appealing to you.

I guess it's all relative. I don't know how much of a return on your investment you are going to see for the expense of making your truck more fuel effecient. If you don't change the final drive axle ratio, install an O/D transmission and seek to maximize the efficiency of your engine (fuel injection, optimal compression ratio, etc.), then you may not be able to do what you aim to do. Those things that our late-models have that relate to fuel economy may not even be doable on our trucks.

Oh, drive like you have an egg on the bottom of your shoes. No "jack-rabbit" starts and no panic braking. Shut your engine off at traffic lights (and hope it starts). Remember that your engine is an air pump. Anything you can do to make it breathe easier....intake and exhaust....will improve your mileage.

But when these trucks were new, 9-12MPG was normal.

[streetstar]

I was reading about LS engine and transmission swaps (late model Chevy stuff) in another thread, and a few of the members are claiming 20mpg + .

Those numbers sound real good for a daily driver. It depends on your restoration budget and what direction you want your truck project to go in ultimately. It takes re-learning some things, but once done, your engine can be tuned with a laptop. As i said, not the right choice for every project, but it might be something to consider

[oldgold70c10]

Feul Economy has been one of my big goals since I got my truck. So far, I think I've done a decent job of getting it there.

I just recently did a cam/carb/intake swap, and have gotten 16 mpg average over a 250-mile trip that had a lot of idling and city driving. You can see my enigne and drivetrain particulars in my signature.
I am using a Weiand Stealth intake, an Edelbrock 1406 carb, and a comp cams cam 12-238-2. I have done some tuning on the carb and will take it out again this weekend an see if my milage increases any. If my engine had a valve job, I suspect I could do better, both in performance and economy, so you should be able to do just as good, if not better.

[Dano69c10]

Just some suggestions;
Lose the A/C, and P/S and anything else using a belt (except the alternator).
Use an electric fan and a manual transmission with OD.
HEI dizzy might help.
Keep your engine tuned up.
The right rear end gear ratios help.
Maybe a fiberglass front clip (or at least a fiberglass hood).
Skinny tires (with proper air pressure).
I removed big @$$ work bumpers off of my trucks, each seemed like they weighed 100 pounds.
Also I don't know which weighs more a wood floor or steel floor bed. Find the lighter of the two.
Just my $0.02
Dano

[myfirstcarwasa73trk]

Which diesel engines fit in our trucks?

[b-rad]

tailgate removed or in the open/down position.
IT IS BETTER TO BE IN THE UP POS OR A BED TARP

[Jim_PA]

Originally Posted by Zonaman

I get a sense that the q-jet is preferred over the Edelbrocks (i.e. 1406) for fuel economy. Would you agree?

They are one of, if not the most advanced mechanical metering devices out there.

The "lowest RPM's possible" theory isn't a good one to follow. You want to operate in an efficient manner. Lowest RPM's possible isn't always giving you the best efficiency.

[piecesparts]

Originally Posted by b-rad

tailgate removed or in the open/down position.
IT IS BETTER TO BE IN THE UP POS OR A BED TARP

Here is where I should have continued on my input. The removal of resistance in the truck bed is essential for every truck. The use of a bed cover or the lowering of the tailgate has been tested by numerous groups nad it does make a small difference over a closed tailgate and an open bed. I run bed covers on my trucks, but there is a thing that happened back 1996 that was a phenomenal event. There were several guys that ran a GMC Sonoma truck on the Bonneville salt flats at a speed around 212 MPH and sustained a new record. They found that the use of a tapered filler right at the rear tailgate to allow for the air to flow through the bed and up over the closed tailgate provided two things: 1) more ground force for the truck at high speeds and 2) less resistance to wind, so that changes the concepts quite a bit. This filler was the equivalent to a piece of sheetmetal going from the bed floor to the top of the tailgate at a 45 degree angle. These guys also found that closer to the ground removed a very large amount of wind resistance (getting rid of the "Brick" effect). (I had the opportunity to talk to these guys on the 96' Hot Rod Power Tour and they were very articulate in their experience) The resistance that really hurts one is the turbulance that is created UNDER the truck in the suspension, exhaust driveline components, and the other things that hang down under there. Take a look at the NASCAR vehicles and how low they get them to the ground. If you create a negative pressure under your truck it helps the resistance and contributes to safer driving.

[b-rad]

I know u can not trust every thing u see on tv but mythbusters did a episode on this and they said it was better in the up pos

[scatesracing]

Fuel Injection