Gas mileage questions...

[radiopilot]

Everyone is aware of the problem I had earlier with the dizzy timing... well I not sure what I did or how I did it and maybe those more knowledgeable could help me understand what I did....

Before I had the problem with removing the dizzy I was getting 20-24mpg average during my trips (I take a 115 mile trip each way - three days a week to my office location) now that is well documented by my careful receipts of my gas and mileage for reimbursement, etc.

Well the manual indicated for FI engines with electronic ignition it must be timed to 14 degrees +/-... and not 10 degrees as for a non electronic /FI car... per the timing light/Fiat manual I have timed the engine and although there is no way for me to measure the 14 degrees timing (no timing marks on the crank pulley) I roughed it in as close as I could but it is pretty much a guess... well the engine stumbles very slightly at 2000, 3000, 4000, etc. RPMs... so it's consistent and the car runs very good... only for the above stumble at those rpms... here is the kicker I am now getting 115 miles on 3.5 gallons of gas +/- (depending on the blend)... that would make it close to a WHOOPING 32.86 MPG... now I know what you're thinking 'can't be' but I am... I continue to this day getting this mileage... it's well documented since I keep meticulous records since I must report all my travel and costs...

Now for the engine gurus here on the forum... what did I do and how can I document it so that others can do the same to prove what I'm saying?

The spark plugs are gapped to 030", new rotor, same ignition wires, same oil (I'm using 20w50 with MMO), and 87 octane gas with no additional additives in the gas, new gas filter, and running a conical K&M type air filter...

What gives with my mpg and how can others benefit by doing this same set up and getting the same results?


Nick

[majicwrench]

Correct me if I am wrong, but it sounds to me like you have no idea what your ignition timing is at?? (no marks on crank pulley)
If that is the case, you also have no idea what your timing was BEFORE all this started. I would guess you now have your ignition timing closer to where it really should be.
Another option, don't recall what sort of dizzy issues you were having, but if you now have a functional vacuum advance and you did not before, that will also dramaticly increase your mileage.

[radiopilot]

Not so... the car ran fine before I removed the dizzy to install a new o-ring... but the timing was off since I reinstalled in at a different location... regarding the timing marks on the crank... I do have the marking pointer ie: 0, 5, 10 degrees... but the manual indicates a 14 degree timing for FI electronic ignition cars... look it up... there is no timing pointer indicator for 14 degrees on my car or maybe other FI engines... someone verify this for me please.

Vacuum advance was working before and now... there is nothing different on the car besides a new dizzy o-ring and the new timing... but who here on this forum is getting close to 33mpg on their cars right now? I'm getting the same gas I've been getting for over 3 months at the same gas stations (2).

Nick

[majicwrench]

Well, if there is nothing different "besides a new dizzy o-ring and the new timing" obviously the "new timing" is the difference. What do you mean by "new timing"??

If you have "new timing" it would seem that is the reason for the increase in mileage.

Maybe I should find your old post...

[BEEK]

i have a heavy foot, i get around 20mpg. carbed 1800 spider. i love to hear the secondarys open thru the gears. then a reasonable cruse. have a 4.30 rear end and small tires, so rpm's are up abit. i have driven many efi spiders and have never gotten more than 23-25mpg, must be me

[Razooli]

I do have the marking pointer ie: 0, 5, 10 degrees... but the manual indicates a 14 degree timing for FI electronic ignition cars... look it up... there is no timing pointer indicator for 14 degrees on my car or maybe other FI engines... someone verify this for me please.
Nick

Nick,
FYI, my owner's manual and my shop manual both say the static timing should be 10° BTDC for the electronic ignition cars. I think you're getting the 14° figure from the vacuum advance stats.

My manual states:
Ignition Distributor (1979 and on)
Static advance : 10°
Centrifugal advance; 28° ± 2°
Vacuum advance
California (carb): 10° ± 2° @ 12 in. Hg
49 States (carb): 14° ± 2° @ 12 in. Hg
All (fuel injection) 15° ± 2° @ 14 in. Hg

The timing pointers are indeed only for 0°, 5° and 10°. I have my static advance set at 15° and use premium. I get in the 30+ MPG range with straight highway driving. Add any city driving to that and I usually get around 20-23 or so depending on how heavy my foot was during that tankful.
Lynn ...

[radiopilot]

Lynn,

You are correct... just looked it up... the timing is right now set as per the manual at 10 degrees... it was set at just slightly below the 10 degree mark prior... still I am getting very good mileage... how can I account for this as the car was getting approx. low to mid twenties mpg (maybe it was set wrong previously) and now it is set correctly so the mileage has gone up... still I can't believe I'm getting this mpg right now... I'm very pleased it has turned out for the better...

Thanks again...

Nick

[beachboy]

Nick, where can I buy that o-ring

[Razooli]

Nick, "Tony" is up there smiling down on you for all the great work you've done on all our clocks and gauges!!! What goes around comes around.

[radiopilot]

Nick, "Tony" is up there smiling down on you for all the great work you've done on all our clocks and gauges!!! What goes around comes around.

Lynn... Just a note that I recieved a letter from the charity you donated in my name... Kudos... I now have a place to send donations in the future.

Cheers,

Nick

[narfire]

Nick, I'm getting about 30-32 mpg but that is imperial gallon-- (about 4.5 liters/gal) on a slightly modified 2L FI engine.
30 mpg on a us gallon is great news... are you a hyper miler as well?

[radiopilot]

Nope... not a hyper miler on this vehicle but I try to coast and not go over 3500 RPM on this car... sure it opens up nicely but I consider anything higher than 3500 rpm as high wear on the engine... the car is not modified other than the K&N type conical filter... I am considering adding an oil catch canister after the cyclonic trap to catch oil that seeps into the plenum... I've read this is not good news for the intake... they can be bought at Ebay and other auto specialty shops but I think I'll make mine with special features to insure only vapours and not liquid oil gets into the plenum.

The drive to and from my office is a straight shot 115 miles each way... so this part is well documented and I know what I spend on gas and mileage... it has increased significantly to just about 32-34 mpg and it is the best this car has ever done since I've owned it. So something has changed somewhere and it has to be the timing... also I'm not sure the dizzy pickup on the rotor is gapped correctly and will check later since I removed it when I removed the dizzy to clean everything up... maybe the magnet/pickup is not located as it was in the previous location... the spark gap was .028 prior and now I have it gapped at .030-.033 but I doubt this is contributing to better gas mileage... the other thing I could consider is the gasoline blend is different for this time of the year... but I was getting the same mileage per gallon last year and the year previous 20-24mpg...

I'm stumped but glad it has happened.

Nick

[wikkid]

Also interesting that you are using 87 octane regular unleaded, as opposed to what the owner's manual says, which is premium. The car feels strong and even as it is now, in addition to getting great mileage?

[racydave]

Hey Nick! I just wonder if something was previously binding, such as the centrifugal adv, or vac advance? My theory on the timing settings is that these settings are adjusted to best pass the emission standards of 1980. That doesn't mean that you car will preform the best at these settings. The best way to accuratly set your ignition timing is with a timing light that is adjustable. Denise has the best, a Snap-on. Mine is the lowly Craftsman unit. To set the static timing at idle (with no vacuume to the vac advance, And the centrifugal advance should not be adding at these RPMs) you watch the mark, then dial the timing light till your mark at the pointer on the crank is at zero. Look at the numbers on the light, it will show what the timing is, ie 10 BTDC. Now, even more important is to check the total advance while at higher RPMs. With no vac to the advance ( plug the hose with a golf tee ) rev the engine to a steady rate faster than required to achieve the centrifugal advance (3,000 ) and check the total advance by dialing the light untill the pointer at the crank is at zero. Reading the numbers on the light will tell what the total advance is. My experience with the dizzy that was originally in my car was that the total advance was to low, and that meant the performance was lacking. So, I opted to set the total timing at 36 BTDC and re-check the base timing. Now the base timing was to advanced, and I coulkd not achieve the curve that I wanted to obtain. The compromise was to set the base timing at approx 17 BTDC which increased my total by an extra 7 degrees. The idle seemed alot smoother, and it was more responsive than before. BUT, I still did not have the total advance I wanted, so I opted for a adjustable system. The other option is to experiment with the base settings, and total settings, and send the dizzy out for a re-curve with a good idea of what I wanted the numbers to be. Work with the distributor re-curve man, as he may have a good idea on the numbers too. Also to be considered is the curve for the centrifugal advance as to when it advances, and how much. I opted to put weaker springs on it to have the advance come in quicker. That also helped pep her up! Currently I am running a base of approx 17, and a total of approx 38. These are all by the Butt dyno, so your results are up to you and your own Butt. Just wish I could attend Dyno day and be a little more precise. Results may also vary according to your mods. Im thru now... PS, I run 87 octaine without any problems. Now im done...

[racydave]

So I lied. Im never done. Before you do anything, obtain the numbers of where it is now, for referance!!! And since Mark has a new system, he should have an opinion on the numbers too! I would like to know!