My car gets terrible gas mileage. Here is what I have done. New carburetor (rebuilt), pertronix coil, fuel filter, pcv valve, changed from points to electronic ignition. (I bought it used from someone on here). New plugs (put them on before the electronic ignition.) The Ignition came with used wires that I used. Would this be the first thing to change? I have read that these I6 200's should get about 22-25 miles to the gallon. I get about 14. How do I troubleshoot? Should I use a different plug with the new ignition?
new carb doesnt mean it was tuned properly for your car either. does the exhaust smell rich or anything? 22-25 might be on the high side but 14 definatly sounds a little low
Sorry, I did not mention timing in the original post but I did have it timed with a light. With regards to the carb, without hooking it up to a machine, how do you get the mixture right on the carb? Ive been told move the screw until it almost dies and then back it off from there. Any other suggestions?
there really wouldnt be any way to get it perfect with out an oxygen sensor but you can play it by ear and take a few test runs. usually they say screw the jet all the way in and back it out 2.5 turns also did you reconnect the vac advance with all your upgrades to the ignigtion and new carb? its the 1/4 in vac hoise from the dizzy into the carb
Only the idle mixture is adjustable, the main jet would need changed if you are running overly rich. For the idle mixture, I usually turn it all the way down and back it off 2 1/2 turns. Timing is the number one thing I would check. Dial it in for about 10 degrees of base timing. What year car is your distributor out of? I most recently drove my '72 from NC to down south of Atlanta and then home again about 30 miles north of Atlanta. Got 26 highway running 65-70 mph... I have MSD ignition and wires with platinum plugs and a header, and have got my mechanical and vacuum advance dialed in pretty well.
Make sure your vacuum advance is working - the diaphragms do tear and leak. Set your timing as advanced as you can without preignition - probably 10 - 12 BTDC. (just to be on the safe side disconnect the vacuum advance and plug it when setting the timing) Putting new wires on won't hurt but if your engine is not missing it may not help either. Set your plug gap at .028" and put in a 180F thermostat. Reconnect the warm air system to the air cleaner housing. Connect a vacuum gauge to the intake manifold and mount it where you can read it while driving. Never let the vacuum get below 10 inches of Mercury while you are driving and I will bet you get closer to 27 MPG than 20 MPG.
Even with points, I was not running plug gaps that tight. With a stock Duraspark II system, I'd be more in the .035-.038 range. With his Pertonix coil, I'd go with .040. I'm running .053 with the MSD ignition and platinum's. 924Mav, when you converted to electonic ignition, you did do away with the low voltage wire to the coil, correct?
here is one thing you deffinately need to check. go to the doc and have your right foot weighed and compair it to your left foot. if it weighs any different, have it xrayed and check it for lead. if you ate paint as a child, it might have manifested itself in your right foot. that would explain having issues with mileage. 0=) sorry, couldnt resist... that was my problem. my ex wife got 22 mpg in our old aerostar 4.0l and i could only get 17. but i ALWAYS got there first.
924Mav, when you converted to electonic ignition, you did do away with the low voltage wire to the coil, correct?[/quote] Jamie, I am not sure I did this. Do you remove the wire completely? Which one is the low voltage wire?
I do have a little miss when idleing. I thought that was normal though for these I6's. What type of wires do you recommend and what plugs would you use with that .028 gap. Jamie mentioned a "doing away with the low voltage wire" on the coil set up since I changed to electronic ignition. Which wire do I remove?
Mav, I use Autolite plugs, 8mm magnetic supressor wires (there are a few brands and they all work). Jamie was talking about replacing the Ford resistor ignition wire from the switch with a non-resistor wire. It supplies battery volts and more amps to the aftermarket ignition system. It is the wire that powers the coil + terminal. Check your installation instructions. Some systems want you to run full battery volts to the coil and others want you to use a resistor. If you are suppose to use a resistor then just use the ignition wire in the harness that goes to coil +. If it calls for no resistor then you will have to run a 18 -16 gage wire from the IGN terminal on the switch to the coil.
Jamie, Some guys like to run a wide gap. I like the narrow gap for these reasons: 1 It lowers the voltage requirement to fire the plugs. 2 Lower voltages make the plug wires last a longer time, coils run cooler and the lower the voltage the more amperage there is to light the fuel. 3 Smaller gaps are less likely to miss at higher RPM 4 Tune-ups last longer If you have ever played with a coil tester you find that the smaller gaps will burn paper, light matches and burn wood while the wide gaps won't do any of that. There just isn't enough amperage left to cause the heat that is required. There is just so much power (watts) from the coil. The lower the voltage the higher the amps, and the higher the volts the lower the amps. Power (watts) = volts x amps. There is a drawback to gaps that are too small - they tend to miss at low pressures, like at an idle so you have to have enough gap to fire the plugs at an idle. Any more gap than that is just a waste.
