6 mpg... please help

[bitchin85]

I have noticed that my choke opens most of the way but not all the way and my truck only runs about 170. I think tomorrow I'm going to throw a 195 thermostat in it and see if that helps. And the carb has about 3k miles on it so I don't think anythings worn out on it just yet

[russgt]

The carb probably isnt worn out, but the choke blade could be getting hung up on something and not opening fully. Was the edelbrock new or a reman?

[68 TT]

21" of vacuum is a decent number pretty close to stock so you should be doing much better on gas.

Mine pulls 13" due to a fairly large cam and even with 5.13 gears, no overdrive and hitting every stoplight red I still get about 8 mpg in the city and about 12 on the highway and I have the same carburetor and ignition you do on the same size engine.

Something odd is going on with your setup. We just need to figure out what it is.

[piecesparts]

Originally Posted by *****in85

I got a long bed 2wd with a 355 with 305 heads, edelbrock streetmaster intake, edelbrock 500 carb, basicaly stock cam, stock distributor, mallory coil, automatic th350. Its got a 2.73 rear end and 31x10.5s... I know its no honda but I drive a lot and I think I should be gettin a little better milage. Also its real sluggish. Anyone have an idea of what It could be? Thanks guys

All good ideas on how to upgrade, I agree on the finding ONE thing at a time and eliminate issues that way. The flow path given is the one that I would use to get this done. Start at the engine's basics and work your way out.

Your outside air temps and the choke setting could be a major part of the fuel consumption. However, you also have to look back at the combination that you are running. The TH350 tranny and 2.73 gears with a 31X10.5 tires could be making you work that truck harder than normal, on a daily basis. I figure somewhere in this discussion there has been some reference to what you are turning for RPMs to get this to roll down the road and what you have to do to accelerate. Taller tires and small gearing numbers for rear ends is not an ideal thing. The opposite of that is the fact that once you have it rolling and if you run too small of a tire diameter, then the RPMs are going to be to high to get decent mileage. So there must be a happy medium, you stated that the truck was a 2WD, so is there a reason for the larger dirt tires?

Once again, go for the engine basics, then look at the air intake---I live in Kansas and lately our temps have been really cold, but I do run open air cleaners. The chokes on my trucks tend to not open properly on a really cold day, but it is only now and then, so I live with it. Heck even my DD TBI tends to run cold choke conditions on a really cold day--so it is a normal thing. Changing to a 195 degree T/stat will help the engine heat up, but the cold air intake will not change, UNLESS you make a closed air cleaner setup. If it was me, I would put in a 180 degree Super/Stat and live with it for a year round temp control. This will make the heater work about right in the cab, if you want more engine bay heat then restrict some air across the radiator. I went to electric fans to get rid of the mechanical fan drag on my wengines--this also eliminated the pulling a lot cold air into the engine bay unecessarily. I also gained a MPG with the electric fan, by the way.

Exhaust improvements will help OVERALL, but for your immediate problem make the upgrades and see what happens there, first. The Flowmaster design will give a better sound and also in some cases better exhaust flow, but that is not a must right now. I still think your problem exists in the gearing and tire combo. I use your discussion about being sluggish as the reference---Timing/distributor components, Carb adjustments, Tires, and Gearing work against you in that area. EXAMPLE: My son's truck suffered when we traded trannys out and we had to change the rear end gears to get the mileage back. We went from a 3.08 gearing to a 3.73 gearing and gained back over 3 MPG---because we put the truck in it's power curve and not lugging the engine when it was doing work.

[bitchin85]

Ok well that will probably be the next thing I do to it. Another thing I was wondering about is would a carb spacer help me any? I have a e inch four hole spacer wittin around and I wondered if it would help with mileage or power..

[68 TT]

Originally Posted by *****in85

Ok well that will probably be the next thing I do to it. Another thing I was wondering about is would a carb spacer help me any? I have a e inch four hole spacer wittin around and I wondered if it would help with mileage or power..

Every motor acts differently. The only way to know is to give it a try.

[piecesparts]

Do you have a tach on the truck? If so, what are your RPMs at highway speeds? With your present tranny and rear end combo, can you gain there? Look at your tire setup, to see what you have and will get from any possible changes.

[bitchin85]

no my tachs broke. im looking for a new one but anyways i put the 2 inch four hole spacer on and took the one inch open spacer off and it takes off alot harder out of the hole but i can tell it dont have as much balls in the higer rpms. i think im going to put the one inch under the four hole. and yes i know this is probably a sad redneck excuse for a righrise lol but other then that i put new accell short u-groove header plugs in and gapped them at .045 and they actually seemed to help a bit over the autolites. and most important no more arcing! but with all the tweaks ive ben making and the 195 degree thermostat(which helped alot) im getting about 10-12 if i baby it. so problem mostly solved... for now lol thanks everyone for the help

[truckincurt]

single plane intakes are for high rpm motors (motors that start makin power around 4 g).. dual plane is for low rpm torque if your motor is stock you want a dual better power and slightly better mpg