Has anyone noticed a difference in exhaust sound by advancing or retarding the timing?Also how should the throttle response be when changing timing?

 

There should be no difference at all, unless you are advancing or retarding timing soo much that you create problems.

 

My custom tune was supposed to have 4 degrees taken out for the nitrous tune, yet the exhaust seems very raspy on the nitrous tune and much smoother on the N/A tune.Also throttle response is much better on the nitrous tune.

 

Theoretically you would get a quicker throttle response but I have a Steeda timing adjuster and I couldn't tell any difference.My gas mileage did get better by two mpg's with + 3 degrees advance.

 

better throttle response from advancing or retarding timing?

 

Advancing the timing.The only time you might want to retard the timing would be with a power adder.Supercharging,turbocharging,or nitrous.

 

retarding the timing will make the engine run ruffer if you retard it alot, so in simple terms yeah it can change.

 

Ideally, in a high performance application you want to run the least ignition advance possible. The only reason we advance timing is because of ignition delay. The problem with most stock cars is the spark is either not strong enough or the mixture is too poor to shorten up the ignition timing. The faster the burn rate the more complete the combustion. The quicker the charge burns in the cylinder the less time the advancing flame has to heat up the remaining charge, thereby decreasing the chances of detonating. If a strong enough spark can be incorporated it will increase the burn rate of the mixture in the cylinder, and require less ignition advance...which inherently decreases pressure rises on the compression stroke as the piston approaches TDC. Pressure spikes on the compression stroke equate to Negative power, therefore we want to fire off the intake charge as close to just prior of TDC as possible yet still have enough time to completely burn the charge. (5* BTDC - 20*ATDC completed burn would be ideal)...

Philip K.

 

This is correct,I have dual plug heads on my Sportster and run with less advance (-5* I think) and got about 7-8 HP on the dyno.Thats just two cylinders,think what could be had with eight.