i recently did the MSD ignition upgrade and gapped my plugs, but i did not set the timing yet, because i don't have a timing light anymore. anyway, before i did the upgrade i was getting about 11mpg. (i drive it pretty hard and the 8th cylinder plug was completely corroded) after the upgrade i am getting about 8 or 9 mpg, and im driving much easier since i noticed the drop in mpg. my question is can the timing being retarded affect gas mileage this bad?by the way, timing was set at 9 degrees btdc before the upgrade to compensate for a ping, which was caused by the corroded plug. sorry for the lengthy post and thanks in advance!

 

Maybe you should play with your distributor back and forth while its running (warm) and see if it changes the smell without draining the performance. is your truck mostly stock besides the ignition upgrade?

 

oh yeai put mine a 16 deg and got about 5mpg so i put it back to 10deg

 

Not sure what the problem is w/ your truck, but my 87'302 gets 23mpg @ 65mph and 19mpg @ 80mpg. 16BTDC/87 octane. A/t w/ stock gears & tires.

 

The motor i was refering to was in my 88 bronco it is a 1973 351w with a cam and 650cfm carb and vacume advanced

 

Seafoam your combustion chambers first. Borrow/rent or buy a light. 1-2 degree increments aren't going to be an option to you w/o a light. This isn't something you should 1/2 *ss! The biggest problem w/ 16BTDC is avoiding the temptation to put your foot down hard, especially from a stop, because it's fun playing w/ your new found acceleration. It will attain 40mph rather effortlessly anyway. Running through your gears is where you use most of your gas. Bumping the base time will increase your MPG more than the rest of the upgrade. You should have no Vac leaks, good, stable fuel pressure that doesn't drop off as soon as the engine is turned off. No active error codes, and balanced compression, all of this info known before doing the upgrade. Have you even done a compression test on it? What are you calling an ignition system upgrade? Just a higher output coil? What exactly did you do?

 

So what's the purpose of comparing it to a stock EFI engine that's ECU controlled?

 

hey just trying to help thats all. remember two heads are better than one, or in this case about 35,000 members. but good point on comparing it to a EFI motor. sorry to confuse you.

 

my truck is completely stock except for new new spark wires, cap, rotor, and ignition coil, which is what i was referring to as the ignition upgrade. the truck has good balanced compression, it was checked by my mechanic in november.

 

What's stock gap for your engine? What are yours at? What Voltage Coil? Seafoam the Combustion chambers. How's #8 behaving? Error codes? Fuel pressure check w/ bleed down time.You could have a/some leaking injectors! If you can't run stock base timing, there's something very wrong.