mpg(or lack thereof)

[rja]

only getting about 14-16 mpg out of this '74 1800. 34 dmsa, dual points; pretty much factory stock. air pump gone. no fuel leaks i can see. do i just need to keep my right boot out of it or what? seems like it should get better than that. timing is set to zero (tdc) at 850 rpm. temp gage reads low, but ir thermometer on top of radiator reads 195f when warmed up. any thoughts; or did i just happen to buy the "fuel funneler" edition? (advance 'til i ping, maybe and back off a hair?)

[RRoller123]

On the low end these little cars get about 22-24, as mine does, and I have heard of people getting much higher, so something is up for sure.

[Fi8spider]

Does the 74 have electric fuel pump? It could be overpressuring the needle and seat in the carb?
My 74 use to do that after a hard run and you could smell the raw fuel even with no fuel leaks.
If so, do you have a fuel return line connected from the carb back to the fuel tank?

Idle is what it is. 850 or 950, it wouldn't really make that much of a difference to fuel consumption.
Timing set at TDC doesn't sound right if that's where the car runs best. Are your timing marks lined up spot on?

I guess there would be a whole bunch of places to start but these are ones that come to mind.

Ping is pre-ignition, spark to the combustion stroke is arriving early so your not getting the maximum from the BANG? In turn the engine wouldn't be operating as efficient as it could. Backing off a hair? How does the car run when set on 10 BTDC?

Spark plugs? Are they correct heat range?
Are the secondaries coming in too early somehow?

Or

Maybe you just love the sound of that Fiat Bark and the right foot needs to be put on a leash?

Make a change at a time and monitoring it would be the way i'd manage out of the situation...There's money to be made with good fuel economy, no doubt.

[Fi8spider]

Could even be a combination of small issues.

Are you draging brakes? Geees the list goes on the more I think about it.

[TX82FIAT]

Some great advice from Fi8spider. The list of what it could be is endless. I would start with the carb and make sure it is properly adjusted. My guess is that the issue is somewhere in the fuel/air delivery. With that said, if your foot is always hard into the pedal then you could burn that much gas. Have you pulled the plugs and looked them over?

[So Cal Mark]

I'd set the timing at 10btdc and make sure the advance is working. Then measure the CO under load throughout the rpm range. Make sure the water-heated choke opens quickly and completely (haha, as if that ever happens)

[vandor]

What kind of driving do you do? If you only drive in the city and are a lead foot, then that mileage may not be that far off.
I usually get 21-22 in easy city driving, and 26-28 on the highway.

[BEEK]

18-20 is what i get, but its full throttle acceleration thru the gears every time

[Razooli]

I get 16-18 around town which is a lot of stop-and-go, red lights, speed bumps and school buses disgorging urchins in every direction. Suffice to say 1st and 2nd get the right foot into them ... 3rd not so much because I'm just to the school speed limit of 25 (the radar sign tells me so in big flashing lights), so I coast an eighth-mile until the next oil pan-eating rain ditch or stop sign. Ad infinitum.
Last week on my hour trip to the Mt. baldy drive, I got almost 31 mpg ... All 5 th and some 4th on the freeway. Constant 70 -80mph.
So if you're doing heavy-footed town driving, you're right in the ballpark. Before you assume that there's something mechanically wrong, take a couple types of drives tO see if aNythings changed. Might not be anything but varied conditions leading to the lo mpg.

[rja]

lotsa replies-thanx guys. 0 tdc timing at 850 rpm is what the sticker says on the car. guess that's prob for usa emission purposes. will try 10 btdc. no dragging brakes; just gone thru. always first thing. no strong gas smell; maybe a little percolation after hard run. plugs are n9y and are pretty clean (although not much time on them). lead-footed driving for sure; it's new to me. and it seems to run well w/this timing. manual choke only, and seems to pull off completely. haven't looked at the advance; still but pulls well, especially in the upper rpms. don't know much about carb adjustments; just the idle speed and mixture and don't think this could have too much emphasis on the mpg. but please correct me if i'm wrong. tire pressures good, too. probably need a steady-state long distance run to really tell; just haven't trusted it or really had the time to do so. just the 10-20 min type jaunts (spirited). ya know, the ones we really like! thanx again guys; will be keeping you apprised. ron.

[Fi8spider]

...and who wouldn't agree, you have to drive it the way you feel otherwise it wouldn't be worth owning. This aint no Toyomistuhyuidaithingy we're talking about

Even though I'm putting this all down to lead footeritis the topic of mpg could well be called "how well is my Fiat tuned".

From a logical perspective it sounds like you're aware of the areas to look at and you go on to question fuel mixtures, I'd say fuel mixtures do have a bearing on fuel economy and can be tuned once timed in correctly. Gas analysers (CO2) are great in these tuning situations.

If you're interested, here's a chart from mirafiori.com laying out factory specs for just about all USA model 124/131 Fiats.
http://mirafiori.com/~pete/miscpics/fia ... _specs.jpg



Here's another one! Engine compression, or lack of it could lead to higher fuel consumption too, as does an exhaust leak.

[FiatMac]

only getting about 14-16 mpg out of this '74 1800. 34 dmsa, dual points....... timing is set to zero (tdc) at 850 rpm.

Noticed that you have a dual points distributor. The factory specs call for timing of 0 degrees on the main points at 850 rpm. With the main points on 0 degrees, the aux. (Cold Start-up) points will fire the engine at 10 degree BTDC until the engine temperature reaches 60 degrees F(they are on a thermal switch). If you are going to advance the main points to 10 degrees BTDC, then you will need to bypass/eliminate the start-up points, or you will have 20 degrees advance when starting a cold engine. The other option is to modify the wiring so that you are always on the cold start points and set them for the advance that you want.