Hey, I jsut recently reset my timing back to -10 deg BTC. But, the truck smells a little rich. Since I have seen people say that they set their timing a little off from 10, I was wondering how you justify sometihing other than the 10. What would cause the truck to need the timing advanced or retarded? Wouldn't that imply something very serious, like a bad timing chain or something? And, if you do need to change the timing, what metric do you use to know where to set it (i.e. sounds right, smells right, highest vacuum at idle).

Thanks.

 

it should be 10 degrees btdc.

with the spout out of course.

 

does it ever need to be advanced or retarded, as some seem to do?

 

There are 2 issues here. You say your exhaust smells rich? If it is and milage is poor you have a problem you need to fix. That's the first issue.

The timing is the other issue. The number of degrees the distributor is adjusted to is a baseline for the rest of the ignition advance. All motors take advantage of additional advance to produce more torque and increase milage, first there were mechanical advance systems, old carb motors did it with a vacuum advance, then came electronics and now it's all done with computers. The factory sets the distributor to something that will provide good power but won't make the engine too sensitive to detonation. There is usually a bit of wiggle room in this setting and production tolerances mean some motors will take more advance before pre igniton than others. You could also use a higher grade fuel and add even more advance. Newer engine designs use knock sensors to utilize as much ignition advance as a motor will handle, the computer is programmed to keep adding advance until it produced detonation(spark knock), and then hold it just below that level. So the moral is more advance is good, so take as much as you can get without doing harm to the motor.