Side Note - I own a graphics Shop, so any fellow wheelers needing any decals, banners, signs, etc. E-mail me and you'll get em' cheap. ALways looking to help out fellow wheelers, clubs, etc.

You are far more than welcome.. Junkie thank YOU for having the good sence to recheck even though you KNEW you were good! And then having the cajones to get on here and give the true answer to your problems... Few even bother.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Now for the rest of you time-by-ear guys. The timing requested by the engine manufactorer is a number... Lets say 6 btdc.. In case you do not understand this it means the spark will occur 6 degrees before the piston is at the top of it's stroke.. Now the crankshaft and rod being in the normal arc at 6 deg the piston is ALMOST to the maximum compression..ALMOST! So the fire is lit before the maximum compression is reached and by the TIME the max compression IS reached the mixture is completely engulfed in the flame. This is where the maximum pressure is about to be reached.. AS the piston travels downward from the extreme pressure everything works just fine..
NOW change the timing a few degrees... Well the degrees are not symetrical degrees in so much as the mechanical turning goes.
One must understand that the degrees are the degrees of a 360 deg circle of the crankshaft.. The time the spark occurs can be too soon or too late if only 2 or 3 degrees from expections. If too soon the pressure rises from the flame BEFORE the piston gets to the top of it's stroke...effectively SLOWING the engine! If too late the maximum pressure is realized when the exhaust valve is opening and causes loss of power and a great deal of heat in the exhaust..So a few degrees at the timing mark are CRITICAL! Even though the crankshaft is traveling evenly in a circle the piston STOPS twice in each circle!!! Please get this in your minds! It STOPS DEAD IN IT"S TRACKS! Few have considered this when setting the timing. Ok so armed with this tiny tidbit some of you just MIGHT be running out to the garage to reset the timing...anyway I hope so.
Good! That is why I spent the time.
Big Jim

Ps.. PISTON STOPS DEAD IN IT'S TRACKS!! Didja ever think of this before? <img src="/forums/images/graemlins/pfft.gif" alt="" />

Good explination BJ. I had never thought about the piston stopping before, but I guess it would have to at the top and bottom of the travel so it can change directions.

Learn something every day <img src="/forums/images/graemlins/patriot.gif" alt="" />

I'd just like to tack this on with BJ's info.

We light the flame off before top dead center so that the fuel has burnt and made maximum pressure for the longest time possible before the exhaust valve opens. You want to run as much advance as you can without having the engine knock. When you run the hairy edge between knocking and running with lots of power, lots of NOx(smog forming gas) is formed in the process. Auto manufactures know this and have the engine set at a happy medium between running strong and running clean. If you have to pass smog or care what you do to the environment run the number the manufacturer suggests.

Fishtaker I will add this for you to chew on..
If your engine is turning 4000 revs.. ALL of the pistons STOP every .0075 sec. Or 8000 times a minute.. Them things take a beating.
Nascar is turning 9000 revs for 500 miles. That is stopping the piston every .0034 sec! Remember it stops twice on every rev. Usually a failure is that the piston ROD streches and gets too long and hits a valve.. It is rare that the piston itself fails.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />