Squeezing more mileage out

[TurnNBurn]

I recently got a 89 R3500 with a 454. I was trying to think what I could do to get a couple more mpg out of it. Previous owner said its gets 10 all day, 13 with tailwind. I was thinking of a few things to maybe get a couple more.

I was going to start with coated or fire wrapped headers and run dual 2.5" with a x pipe , good tune up (plugs wire etc), a hotter coil , k&n filter Id like to do a cold air thing but havent looked into it much. I found a tbi spacer maybe that, pull the driven fan and go to electrics.

Is there anything else I could try? Will headers from a 78 2wd fit this thing , it sure looks like the same setup. any sugestions

[Prerunner1982]

Keep your foot out of the gas as much as possible and use Non-Ethanol gas if you can.

[TurnNBurn]

Yes true but it has low gears and the low 4 speed manual. Running down the road at 55-60 its turning quite fast.

[THE "10" SILVERADO]

out of what you mentioned I would think an ignition tune up and headers would make the most difference. 10 with a 454? that's pretty good, your beating my 6 with a 2bbl 350

[jimbonice]

From the perspective of owning a 454 crew cab dually, I believe you are close to maxed out on your fuel economy. An open air cleaner and dual exhaust may help some, but I have all that plus an overdrive trans and I might be at 14 on the highway.
Thanks for helping to support our tar sands.
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[TurnNBurn]

I will prob do ignition and exhaust and see where that takes me.

[jimbonice]

Recurving the distributor helps regain some power. These things will take a crap load more initial timing, as well as total. When I bought my truck it had a frozen distributor, as well as, I swear, the original plugs which had no electrodes left. I drove it 400 miles home like that. After replacing all the old ignition hardware it certainly ran better, but my economy hardly budged. Having the drag coefficient of a barn probably has something to do with it.
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[rs72z]

His is fuel injected, so the ecm takes care of timing.
I would suggest someway of lowering the rpm's. Either a overdrive trans or a gearvendors overdrive.

[jimbonice]

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Don't 1987 tbi's still have an hei? I believe they do, so setting the timing is still part of the fun. Unless lots of miles are being driven, there's not much of a return on investment going to an overdrive trans. I know, because I've got one. The real benefit is not having to listen to a 454 screaming at 2800 rpm on the highway.
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[tucsonjwt]

I have an 83 454/granny 4 spd, reg cab, carbureted. 10/13 mpg is the best I have ever seen, and I try to keep it in top mechanical shape. If you look up estimated mpg on these heavy trucks on the new vehicle discussion sites, especially with a big block, you will not find any higher mpg reports. I try to drive my truck as little as possible. If I need to travel a long distance I rent a car for about $13/day on sale, which more than compensates for the cost of the rental in fuel savings.

[rs72z]

Originally Posted by jimbonice

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Don't 1987 tbi's still have an hei? I believe they do, so setting the timing is still part of the fun. Unless lots of miles are being driven, there's not much of a return on investment going to an overdrive trans. I know, because I've got one. The real benefit is not having to listen to a 454 screaming at 2800 rpm on the highway.
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They dont have the same hei that the 86 back had. 87 up uses a external coil and although you can adjust base timing the computer controls the advance curve. if i am wrong please correct me. I know that's how my 87 350 is and pretty sure the big blocks were the same.

[kriswvu1202]

I think your best bet as far as bang for the buck would be a taller set of rearend gears. It will lower your rpms on the highway. Reduced engine speed = better mileage. I did this with my Jeep and went from 15-17 hwy to 22...and that was with a 4" lift and 33" Mickey Thompsons. I lost some grunt off the line, but that shouldn't be much of an issue with the 454 under the hood. Junkyard rearends are a dime a dozen. I bought a front and rear both for $200.
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[kriswvu1202]

...and at the risk of stating the obvious, if your truck is 4wd you would have to change BOTH front and rear ring and pinions to the same ratio. Otherwise when you shift into 4wd your transfer case will go bye bye.
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[INSIDIOUS '86]

Originally Posted by TurnNBurn

Yes true but it has low gears and the low 4 speed manual. Running down the road at 55-60 its turning quite fast.

Fix those gears and you will be getting way better mileage try the a833y manual trans with the overdrive it's a 4spd too or change the rear gearing to .
3.23 headers and 2.5 xpipe will work good as well as an electric fan

Also cut weight anywere you can
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[Cue-Ball]

I don't think you're going to do much better than 10/13 no matter what you do. My truck is a 305/TH350 2WD and I don't get much better than that.

[76stepsidechevy]

I don't even get that kind of mileage with a small block and the sm465. Im fooling with a holley fuel injection setup now and just went from 33 to 35 inch tires last week to help drop my rpms on the highway. 3.73s and no overdrive with the 31s the truck came with was not pretty at all. I can cruise at 65 at 2200 rpm now, thats made the most difference so far. I still have some tuning to do with the fuel injection though, hopefully I can pull some more mileage out of that. If I could get 12 mpg out of my truck i'd be happy.

[TurnNBurn]

ok I appreciate the help , it is a tbi with an external coil dist.

[donut]

IMO, it's all incremental. There is NO way that your truck will get good mileage, (they still can't).

That stated (I know, "Capt' Obvious") Maybe a small "RV" cam? Make sure it'll work with your electronics, I know they make them. Tune to the best of your ability, though with the mileage your getting, I really wouldn't expect much more. Don't be sold on all the "whiz bang" gizmos for mileage. If they worked so well the OEM's would use them.

You've got a tow mule. If you don't use it for it's intended use, then cheapest would be sell and get something else.
Evaluate what you want to do and if it's realistic with what you have.

[esbstuff]

I installed a Edelbrock Performer 454 TBI Intake Manifold 3764 and matching cam 2162 in a 87 and i am very pleased with it. The truck is a wrecker (454/400/205/4.10's) that I used daily and I am getting 9/10 mpg average. No problems with stock computer/chip but I have been told there is a minor bump in mpg/hp for a chip with this cam/intake in mind, I just hadn't had the money to spurge yet.

[andrewmp6]

And don't use the header wrap it will hold moisture and make them rust out faster.

[chevymotocross]

Pretty much what everyone here said is on point: It's a big one-ton big block truck, mileage will never be great with this setup but it's understandable if you want it at it's optimum.

The dual exhaust with the x-pipe would be great. Headers would probably be wise as well.

Obviously make sure the engine is in the best tune it can be in (fuel filter, air filter, cap, rotor, timing). Use AC Delco plugs and wires. I wouldn't even mess with the aftermarket ignitions or blaster coils etc. Base Timing, atleast on the SBC TBI engines is 0, not sure on the 454 but on my 305 TBI, it ran best with the base timing a few degrees advanced.

Wouldn't hurt to do a TBI rebuild kit (can be bought at most local parts stores). Just did this to my 305 and I was pretty surprised at the improvement.

The TBI spacer does infact help. I added one to my TBI and throttle response is certainly better.

Get your tire pressures even and up to spec.

Drive slow

Besides that, you will be having to invest in higher priced, more labor intense modifications which probably won't justify the minimal fuel savings you would get such as:

Better cam, and heads: Great, but expensive and then you will run into computer issues so you may infact not even yield better mileage unless you get a good chip burn which really means you must data-log which costs more money and more time.

Finding an overdrive transmission or gear vendors OD

Electric Fan: probably not too pricey but I would think it's somewhat labor intensive for the minimal gain

Gearing Change: probably expensive for a 1-Ton and then you may lose towing power to get your highway RPM down which means your mileage would probably stay the same or worse.

Tonneau Cover

[tucsonjwt]

For reference, Gear Vendor advertises a 20% improvement in fuel economy. This is only valid if you are driving over a minimum speed (say 40 mph), so it is mostly a highway driving advantage. I have a GV on my 83 454/4 spd granny tranny, and I got about 20% improvement in gas mileage when I started using it, but since I travel mostly city driving it does not do me much good. The GV effectively changes your final drive ratio by 20%, theoretically giving you "extra gears" between your normal gears. So, I have a 4:10 rear axle and have a 3.28 effective rear axle ratio with the GV engaged.
Even used GV and GV adapters are pricey (check Ebay). Consider that you need to shorten/modify your drive shaft to install one, you are looking at $3.5 - $4.5K installed new, and maybe $1K less for used. I did read somewhere that GV will rebuild one of their own units for about $850, so that might make a used unit an economical choice if you got one for a few hundred dollars (not likely though).
Also, I think with an overdrive transmission and lock up torque converter the GV is of little or no fuel economy use, but is supposed to improve performance.