warming up?

cre · 10-20-2009, 07:15 AM

There are two types of timing, doesn't matter if the car is N/A or Turbo: mechanical and spark.

Mechanical timing is where you align everything so that piston #1 is at 0? or TDC (Top Dead Center) and the valves are precisely where specified by the manufacturer and the distributor and cam position sensor (yes our N/A's do have a CPS inside the distributor) point to the #1 position.

Spark timing define when the spark occurs with relation to the location of the piston. The spark is actually generated in *advance* of the piston reaching TDC; hence the term "spark or ignition advance". The thing is that what you're trying to achieve here is a situation where half of the fuel in the cylinder has been burned by the time the crank reaches about 20? ATDC (After Top Dead Center) as this is where the most power is made. So, in order to acheive this the ECU adjusts the spark advance constantly while listening to the knock sensors to hear is the spark occured too soon causing a shock to the system (this occurs if the advance is too great and the fuel is igniting sooner than predicted). As a result of these factors if your timing is too far advanced or retarded you may see a power loss (and possibly a severe one) and your engine and exhaust temps will change. Your spark timing and the burn rate of the fuel is important in determining the octane you want to use in your vehicle. Too high and may lose power... too low and you may lose power... interesting eh?

Setting the ignition timing on these cars is very easy... so easy that it seems a lot of mechanics just can't manage the feat.

EDIT:Oh, and I didn't say I wouldn't help... just not about to take anyone by the hand and walk them through the wonderful world of automotive repair and modification. I am willing to help you out here and there.

10-20-2009, 07:15 AM	#12
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	There are two types of timing, doesn't matter if the car is N/A or Turbo: mechanical and spark. Mechanical timing is where you align everything so that piston #1 is at 0? or TDC (Top Dead Center) and the valves are precisely where specified by the manufacturer and the distributor and cam position sensor (yes our N/A's do have a CPS inside the distributor) point to the #1 position. Spark timing define when the spark occurs with relation to the location of the piston. The spark is actually generated in advance of the piston reaching TDC; hence the term "spark or ignition advance". The thing is that what you're trying to achieve here is a situation where half of the fuel in the cylinder has been burned by the time the crank reaches about 20? ATDC (After Top Dead Center) as this is where the most power is made. So, in order to acheive this the ECU adjusts the spark advance constantly while listening to the knock sensors to hear is the spark occured too soon causing a shock to the system (this occurs if the advance is too great and the fuel is igniting sooner than predicted). As a result of these factors if your timing is too far advanced or retarded you may see a power loss (and possibly a severe one) and your engine and exhaust temps will change. Your spark timing and the burn rate of the fuel is important in determining the octane you want to use in your vehicle. Too high and may lose power... too low and you may lose power... interesting eh? Setting the ignition timing on these cars is very easy... so easy that it seems a lot of mechanics just can't manage the feat. EDIT:Oh, and I didn't say I wouldn't help... just not about to take anyone by the hand and walk them through the wonderful world of automotive repair and modification. I am willing to help you out here and there. Last edited by cre; 10-20-2009 at 07:17 AM.