I just built a 406 and im tring to get it running better.. Ive used timing lights but never a total timing light b4....I have never timed the setup b4 and I am very low on power... I have two marks in the balancer..one is the stock mark and the engine builder put anouther smaller mark at 36*..So can someone tell me how to use a dial back timing light??????

 

Computer controlled EFI engine? Forget it, you can't set you total timing that way. A dial-back light will work just fine but the timing advance isn't something you can set accurately just revving the motor in the driveway like you can on older non-computer controlled setups.

computer controlled setups you just put the timing light at 0* and set the initial timing (per the proper procedure to set initial timing) and that's your baseline. If you don't know the timing curve that's programmed into the chip you just play with the initial timing a degree or two at a time from there to determine what it likes for best power with whatever timing curve is programmed into it. The real magic happens in the chip programming.

 

As mentioned above, with EFI, all you can do is set the base timing and let the computer control where it feels the best timing should be based on inputs from the sensors such as the knock sensor, MAP sensor etc.

With a non computer controlled ignition system, total timing is the sum of the base timing plus the mechanical advance built into the distributor such as an older large cap HEI system.

For performance applications, you would get the distributor recurved so that it would be at full advance by 3000 rpm. You would then bring the engine rpm up until the ignition stopped advancing then check to see where the timing was at. Since cars don't have timing marks that go that high, an advance timing light is required. You would bring the engine rpms up then adjust the timing light until the mark was at TDC. The adjustment on the timing light would be how much total timing you would have.

If you set your base timing at 10* and the mechanical advance had 24* then the total timing would be 34*. Bumping up the base timing to 12* means the total timing would be 36*.

The best way of finding what total timing the engine will make it's most power at is on a dyno. You want the base timing low enough so that the engine will crank over without kicking back and you want the total timing where the engine makes the most HP. Recurving a distributor is the only way to change the mechanical advance.

Since you use a computer controlled distributor, there's little you can do except set the timing to the manufactures specifications and let the computer do the rest. If the engine's octane requirements are not high enough or there's any other reason why the engine may knock, the ECM will detect it through the knock sensor and retard the timing which will result in less power. The only way to know if the timing is being retarded by the computer is with a scan tool.