YotaBoy83

Okay so I have an 83 long bed 4x4 weber 3236, tube header, 2 1/4 inch exhaust, 31" tires, e3 plugs, 20r head, and new bearings and seals. For some reason I'm getting 11 mpg and I don't hot rod it around and it feels down on power for all the up grades on it. Please help me thank you.

Bingle

Hey fellow Spokanastan resident.
Had a similar stetup at one point and was getting 18/22mpg. Check your idle mix? timeing/vac advance?
Is this a new setup on the engine or did it just start sucking?

If you see a big green '81 around town, it's me.

83

It's always hard with these things, since it could be so many things...we have no way of knowing if any of those mods were done "right", but assuming they were, I'd look at:

-What Bingle said...timing, idle, basic tune-up stuff
-make sure the brakes aren't dragging
-Wheel bearings are good


And then more info along the lines of what Bingle was asking. What's the history? These mods were just finished and now it gets bad mileage? Or the truck's been set up like this for a while and the bad mileage only just started happening? Is the Weber new? Used? Old? Jetted correctly? Tuned properly? Engine rebuilt? What was it bored out to?

Bad gas mileage can be caused by sooo many things. Sometimes it's a combination, sometimes just one thing in particular...but it can be tricky tracking it down.

83

I'll tell you, though, that my 83 only gets around 13-14mpg in town, with a rebuilt engine, carb and all that.

YotaBoy83

Well I bought it off the original owner who put all the parts on it but I had to tear the entire motor down due to a knock. It was not bored out just honed, I have adjusted the carb many times the mixture screw is out about 1 1/2 turns the idle is about 800 and float adjust correctly the plugs are brand new. I know the brakes and bearings are good cause I just did them. The timing is between 5 and 8 degrees I think it might be not enough timing. Also I was told to run bigger jets, a msd coil, 18* of timing, and plugs gapped to .050 does this sound like it will help? Oh and the truck did sit for about 4 years before I got it but all fluids were drained besides the oil.

nightstalker

if thats ur truck in the avatar, those big tires will definatly kill ur mpg,s

Bingle

I think I run between 12° and 14°. 18° seems a bit much. Does it seem to lag? Set you timeing and then hook up the vac advance and throttle up and wach the timeing to make sure your advance is working right.
I've got msd and feel it helps some but it's not a big mpg helper. I'm geting about 11mpg but that's warming it up and short trip to work (2mi) and dual sidedrafts and 35's. Long hauls I get around 16 so 11 with your setup isn't right.
Bigger jets would just make it worse IMO. If your jets were gummed up from sitting that could be an issue.

If all else fails, I'd meet up with ya. I'm in the Felony Flats area.

yotaboy82

my 81 only gets 150km to $60 fill. gas is also 1.10/L here in manitoba

YotaBoy83

The tires I have are only 31's they arn't that big. And yeah it does seem sluggish but I took the top off the carb and it looked like new. I do mainly short trips like 3 miles but it is still really down on power. The jets the guy suggested were 135 on the primary and 190 on secondary then with plus gapped to .050 msd coil and the timing he said he was getting about 20mpg with that set up.

YotaBoy83

Would my bad mileage be caused by not enough timing because my timing was between 5 and 8 degrees I just adjusted it to about 12

Weigle

Had a low MPG problem with my new truck too... Found out the fuel pump was bad and dumping gas all over the road. Changed pump for $40 and now get 15mpg instead of 10. It runs sooooo much more smoothly too. See if it's leaking from the bottom.

YotaBoy83

Alright i'll check it but i'm pretty sure its good because I have another pump and I switched it out with that one and it didn't change. I got a lot of spare parts with this truck and it was a steal at $600

wyoming9

iTrader: (1)

Low in power just what are you comparing it with??

When I am used to driving the 22r what ever at the rated horsepower less then 125 hp then drive a 300 hp truck the 22r feels like I am dragging a 10,000 pound sled

Besides the short trips play hell with the mileage I get around 10 mpg with my 4runner going to work and back about 5 miles oneway

Bingle

I agree ^^^^. I get WAY better if I'm Going 40-50 mi down the road instead of just to work and back (3.5 mi round trip). Especially in the winter when you have to warm it up a little in these old carb rigs. Fuel injection you can just hop in and go so you don't waste all that fuel. short trips 10 still seems a little low but not unheard of.

The timing should help, don't know about the bigger gap, and the coil couldn't hurt, though it'll take you a quite a while (if ever) to recoup the cost in saved gas money IMO.

Vac advance seem to be working? Had mine go out and it was a dog.

YotaBoy83

Yeah it might just be the short trips. And I know the vac advance is working I checked it against the other diaphram I have. And I check the timing advances when I rev it up

Bingle

Hmmmm. Got me scratchin my head now. Rocker arm/valve clearance checked? E brake not fully disengaging? Vaccuum leak?

Idle smooth or not? You said you were around 800rpm so I'm guessing it's not too rough.

83

I'd like to know your mileage on a road trip. Like what you get on an entire tank of gas, going 60-65 mph (not up crazy mtn passes the whole way).

I'd be curious to recalculate what my truck gets around town, but I doubt it's much better than what you're getting.

Fixing your timing will probably gain you a couple mpg

85GT-79FJ40

Even a 31" tire is quite a bit larger/heavier than stock. I had an 82 on 33's with a header and exhaust that only got about 15MPG. Yet I've also had later 22RE trucks with proper gearing for the tires (4.88's and 33's, 5.29's with 35's) that both got a bit over 20. That same 82 bone stock got around 20 according to my father who bought it new.

YotaBoy83

Yeah all the brakes check out good it rolls easily, the valve clearance i've checked many times and is good. Oh and these mpg number i'm giving you are when I had 30's. And I am sure there isn't any vacuum leaks. And yes it idles very smooth but has a slight miss every now and then.
I am also curious to what mpg I would get on a road trip only doing highway miles.

YotaBoy83

Oh and with my vacuum advance should the hose be plugged in on the rear or front of it since there are to places to attach it too.