6 MPG is costly...

I'm running a CSB with an Offenhauser intake mounted with three Holley 84 carburetors (I believe...?) with progressive linkage... When completed, I purchased three Edelbrock 94 carburetor kits as suggested and had the pro's with their Dyno install the kits, dial in the carburetors, install a new balancer and run it all on their Dyno.

Sounds good and runs strong... ... But with a ten gallon gas tank I can barely make it 80 miles down the road before I run outta gas...?

What is my best way to go on this...? Don't race - Just wanna drive....

1. Three different new carburetors? Monothrote carbs...?

2. New intake with one small carburetor? Two BBL or Four BBL...?

I'm looking for some new ideas.....................

What has been your experience..... -EZ

0 D

overdrive and 3.OO gears with 3O'' tall tires, that should help.


l use these;

http://www.crawlpedia.com/rpm_gear_calculator.htm


Later

What's your rear end ratio? What kind of tranny? How tall are your tires? All these add up to your final drive ratio. Taller tires, higher gears {lower numerically, I.E. 3:00 is higher or faster than 4:11} will help mileage. With a standard tranny or old style automatic like a turbo 350, final drive on those is direct, same as the engine RPM. Like Skull said, an overdrive would help. There are bolt on overdrives available, like the Gear Vendors, but are pricy.

If the progressive linkage is hooked up right, you should be running on the center carb most of the time. The outer carbs should only kick in when you mash on it.

Bamamav said:

If the progressive linkage is hooked up right, you should be running on the center carb most of the time. The outer carbs should only kick in when you mash on it.

Click to expand...

Yep. Are you getting into the outer carbs when highway cruising?

I'd definitely go with a taller tire on the rear. You might also take the stop off the progressive linkage to the outer carbs & see how it does on the road running just the center carb. Just mark where the stop was before you loosen it or take it off.

Beercan

cheater, sort of

I ran dual quads on my SBF and got not so good of mileage, a thin plate the shape of the base gasket to block off the front carb. linkage, fuel line all connected, even cruise control, looked bad ass and got my MPG back [S

My 23 with a 35o Chev got fantastic mileage when I ran a single 600 cfm Edelbrock on it, one time I got 30 mpg on a long trip, but generally it got about 24-25 mpg. When I switched to two Rochester two barrels on a Vintage Speed adapter the gas mileage went down the tubes. I couldn't figure it out because I was only running on a two barrel most of the time as the second carb never came into play until my foot was in it, but something changed.

I did run 30 inch rear tires and a 3.00 gear in the rear, so I would go down the interstate just off of idle.

Don

A 2bbl is not going to get any better mileage than a 4bbl, unless you are into it all the time......

I would unhook the outer carbs for a while and see what you get...If its still lousy, your tuneup must be way out

How wild is your cam etc?

Here's a view from a different angle. What if the pick-up tube in your tank is too short or broken half way up? How much gas did you put back in the little tank after you ran out? Half as much as you expected? Maybe your tank has been made a way smaller due to a short pick-up tube. Food for thought.

In my experience you'd get better mileage with the 4bbl as long as you keep your foot out of it.

I have a fairly built 283 with a big cam in a lite car (2800 lbs). It's got 3:08's with a 235/60 tire. It's best mileage is 14 with average highway at about 12 and more like 9 in town. That's with a single 4 and a dual 4. The dual quad was set up progressive. If I put my foot into it at all forget it.

I'd consider the jetting on your set up and then look at gearing and an OD as other options.

OK i'll be the bad guy!








Get a Bigger Fuel Tank!! it's a toy! have a good time!

I'm done now I got that outta my system.

I have a 383 with 450 hp, 3.55 gears and 26" rear tires with no overdrive. I get 14 mpg with my foot in it all the time. As said earlier: higher gears, taller tires, get your tune right and hook up the vacuum advance. Get your advance curve right. It sounds to me like the carb tune is way off.

My 6 MPG 'Toy...'

"Thanks" "No Thanks" "...and Gimme a break"



#3 Bamamay - I'm running a T350 Auto with BIG Meats on the rear... Just had the Dyno Tuneup and dialed in the carbs. She uses center carb most of the time... Always around town. I'd hate to run er' too lean and so was afraid to try only the center carb out on the highway.

#4 Sam - I'll ease off on the progressive linkage and see if that helps.

#5 Rusty - Thanks... I'll give that a try in the morning. Hope the center carb has enough juice to keep her at 60 MPH

#6 Soltz - Should I increase the jets on the center carb if I'm not into the other two...?

#7 Don - I know that this 327 will get better gas mileage - I've just gotta sort it out.

#8 Stroker - Mid range engine... Worked on but not over board. Would JUST the center carb use make the 327 run too lean...?

#9 Mac - 12 gallons is 12 gallons... Every time.

#10 Under - I can live with whatever I get... But somethings outta whack if this little lady is sucking it down at 6 MPG...?

Tomorrow's another bright and sunny day.... I'll see what I find. Thanks for all your help.

"#8 Stroker - Mid range engine... Worked on but not over board. Would JUST the center carb use make the 327 run too lean...?"

No...if its using a progressive linkage, its running just on the center carb most of the time anyways, until you put your foot in it. Post a pic of the linkage if you can

ezheimers linkage

Here's what I've done...

The first pic looks progressive, the second pic looks like the secondaries open a little off idle? What are we looking at - as in what set up are you currently running? The second pic?

EDIT: Looks like you added a return spring to the secondaries? I'm not sure you should hook that spring to the throttle shaft - it might cause premature wear.

If you're getting 6 miles per gallon I'd expect to see black smoke pouring out the exhaust.

not slamming you at all, I just think of my stuff as toys, just like a quad or boat. I don't know anything about multi carb set ups was just playing with ya! you talk about bad mileage I had a 2008 Ford Superduty with the 6.4 and got 9 mpg that sucked at 250 miles a day.

Check to see how much fuel pressure you're running. Don't want anything over 5 or 6 psi with these carbs.
Also check the fuel level, in the carb bowls and make sure it's not too high.

6 MPG Toy.....

Thanks for the help on this... I'm learning a whole bunch.

First - My fuel pressure was way high @ 20#'s Floats OK
Second - It runs fine on just the center carburetor. I'll keep that in mind.
Third - The second picture is todays setup - But I'll change the spring load.
Forth - No black smoke. That would be my real 6 MPG Toy at 32 feet - can haul 20 people topside and two Harley's in the belly - Many six packs of beer and a full never ending bar.
Now that's a toy with a bigger fuel tank that we enjoy.............. EZ