Bad Gas Mileage

I have finally started to drive around enough to figure out what kind of gas mileage I'm getting.

Here are the basics:

2065 TIV with Dual Weber 44's, 3.88 R&P.

I just used about 10.5 gallons to go 170 miles. 16 mpg. Most trips were 12 miles (distance to work) or less, and not that much freeway driving. I really have not been putting my foot in it much yet, and 16mpg seems rather low.

I have some longer trips I will be taking and can check the MPG for freeway, but I just wanted to see if anyone has had similar experiences in city driving mpg. I have tuned/balanced the carbs and am pretty sure I'm not running to rich. I do have some leakage problems from the overflow on the tank when it is full, but that should not make up that much difference.

Brand new engine or one that has some mileage on it?

Carbs jetted correctly or don't you know? (Does it backfire on de-celleration at all??)

Under 20 mpg on a brand new engine who's bearings/rings are tight as hell is not unheard of, but I'm wondering how rich it's running, too.

gn

New engine, 400 miles on it. Is there a way to measure exactly how rich or lean it is running except the turn the mixture screw in until it runs rough, then turn it out a bit?

Take a look at you spark plugs, if they're black you're too rich.

Another option is to buy an air/fuel ratio gauge - Here's some info on A/F ratios from Aircooled.net
aircooled.net/new-bin/viewproductdetail.php?keyword2=LGU0016&cartid=0614200529761386

What jets are you running?

Chris,

I'm getting 22mpg (converted to US gallons) from my new Type IV and I _know_ i'm running rich from my O2 gauge and this seems to be, judging by my engine bay pressure gauge, caused by my new fuel pump's internal regulator behaving inconsistently! (I have an external regulator on order to fix this)

There are several options to understand your mixture

* Check the colour of your plugs (as already suggested)
* Use a meter to measure the CO in your exhaust
* Use a special transparent colourtune plug to actually see the colour of your spark
* Use a (wideband is best, but I have the much cheaper less accurate narrowband) O2 sensor hooked up to a gauge

Check your fuel pressure is below 3.5 PSI as spikes above this will cause problems with tuning the carbs.

Be careful not to go too lean also.

I'm finding the dual CHT, dual EGT, O2, and oil pressure & temperature gauges i fitted hugely informative as Jake and I fine tune my engine for UK fuel. So much so that i'm upgrading to monitoring all four cylinders EGT (displaying a pair at a time)

Simon