1 MPG gain

[farside847]

One full tank of gas since I switched to an electric fan, this mod alone
saved me 1 MPG. So I went from 13.2mpg to 14.6mpg. Thought you all
might like to know.

Electric fan swap: http://67-72chevytrucks.com/vboard/s...d.php?t=187724

Truck info: 307V8, 2b carb, 3sp manual, 3.73 rear

Driving: 35 miles per day in the lovely Bay Area traffic. Blech.

Wasnt as big of an improvement as I might have hoped, but hell, its
better than nothing, right?

[shifty]

Just saved yourself $2.50 or more per fillup. If you fill up twice a week, that's $5 saved per week, $20 per month on average which nets you a free half a tank of gas or so, right?

[davidh]

How did you set it up? Did you have to take off the fan shroud? Thermostat for the fans? How much did it cost to do this? I have a 6cy truck 3speed that I was going to put in a 8cyl and keep in the 6cyl positon so this would be good if I am going to use the short water pump. Pictures would be good to. You say 307. all stock 2bbl. Would HEI and a 4bbl help too since the primaries would be smaller?

[72MARIO]

That's good to hear.
That would get me 15 MPG I might consider that for my 84 DD. Now that I have done a cam swap I got the power band down low where I needed it the fule MPG is much better.

[Huck]

Switch from the 373 rear to a 307 and get a 4+mpg improvement on highway. It will also give your engine a extended life!! Switch to an overdrive transmission too and you will get another 3+mpg!! Just think, do all these modifications and you will put the arabs back into their tents!! hehehe

[72MARIO]

I think the 3:73 are doning great. The 3:07 tends to bog the motor down and loose MPG.

[Truck Hippy]

I went the 307/700r4/308 set up before, It wasn't pretty. I had a 70' swb driver. I put in a 307 out of another truck with low miles, still had the 2 barrel, put in a rebuilt 700. Motor ran great. Probably one of the best running motors I have ever had as far a being smooth and didn't use oil. Well on the open road The over drive with the 308 gear killed the poor little motor and I had to really mash it down to mantain speed on any kind of a hill. I shoulda kept the 373 gear. Live and learn. By the way I put the turbo 350 back in and with a super tuneup and driving like grandma, I pulled down 17.2 mpg with that heap.

[vtblazer]

Was the fan you removed a direct drive/flex or a clutch fan?

[Boog]

I would like to see more of a 3 to 4 mpg improvement by going electric before I converted one. Obviously the electric fan will make a major improvement over one with the direct drive fan but I'm not so sure it will make that much difference over one with a properly operating oem clutch fan. I see mention of cfm ratings of the electrics. I have never seen mention of cfm ratings of the clutch type. Just how much air does the clutch fan pull? For a truck like farside's with no a/c his fan will probably do just fine, even in heavy traffic idleing but for the guys running power steering and a/c in summer heat they may have a problem with the single fan. There is at least one guy who installed a Lincoln mark8 fan setup. Sounds like it might be heavy duty enough. Anyone used the dual fan setup from the later model Chevy trucks yet?

[davidh]

I'm thinking of this swap of fans, 305(80's HO Fbody) with rv cam, keeping the 3speed manual, and 3.08's. Maybe some mileage then.

[farside847]

Here is the thread of the fan setup.
http://67-72chevytrucks.com/vboard/s...d.php?t=187724

I had a manual (non-clutch) fan setup before.