Dwell!

[pug309twin40s 1]

just recieved my new gunsons professional tester so i could adjust the emmissions for the MOT on my mi16 twin48 carb goodwood.

 

nice little machine.

 

 

now it has a setting for DWell- ignition timing.. but cant fiqure out how to use it.

 

anyone know how to work out dwell and if i can use it to check timing on my engine? Mi16 with twin48 carbs and using 1.9 8v ignition system.

[crogthomas 0]

Dwell is the angle of crankshaft rotation that the points are closed for, on a conventional (read: Old) ignition system. It bascially determines the amount of time the coil has to build up an electric field. It would depend on the points gap.

Hence I dont think its much use to you with an electronic ignition system, since the Dwell angle is set electronically and is not adjustable.

Edited April 13, 2006 by crogthomas

[Guest rick03054]

I've never used one of those machines but AFAIK dwell isn't much use for electronic ignition I'm afraid.

 

Dwell angle is the amount of rotation of the distributer when contact breaker points are closed. From times of old!

[Mad Professor 7]

The MegaSquirt ECU's also use the wording Dwell.

 

Maximum Dwell Duration (ms) (max_coil_dur) is the longest period the coil is allowed to charge - too long and it can burn out your coil, too short and the spark may be weak. Normally this value is between 2.0 and 4.0 milliseconds. For the GM HEI 'in-cap' coil, a value of 3.5 milliseconds is typical.

MegaSquirt-II attempts to set up a charge/ discharge cycle that charges the coil for the specified charge time, discharges it for at least the specified spark duration time, and then remains in the discharge state until it is time to start charging for the next cylinder. At high rpm, there may not be time to fit in the specified charge + discharge times. In this case, MegaSquirt-II scales down both the charge and discharge times proportionally so they just fit within the time between tach pulses.

Edited April 15, 2006 by Mad Professor