Racintweek

i understand how a reg timing light operates buti cant seem to grasp how a dial on the back of an advance one even needs to be there :1

Cray91

The dial will change the speed of the light so that the marks on the block and pulley will line up at whatever you dial it to.

turbohf

i like mine cuz of the pulleys with all the marks on them... i put the dial to the timing i want, then turn the distributor till the TDC mark is lit up... tighten bolts..... DONE... time to go rip on the car

Racintweek

honda pulleys have TDC, 14* 16* 18* marks. wouldnt using a reg timing light be ok?? if it sparks at 18* then the 18* mark would be lit up right??


how does this dial know when its 18* ?

Bone1

EXCELLENT QUESTION........too few will ever be able to answer correctly.

Without a logic circuit to know the rpms vs degrees of advance, it's all a big guess with a dial back timing light.

FYI they are set to be accurate at 900 rpm.

I'll take a direct read timing light and a fully degreed balancer when setting timing.

16 degrees crank at 5000 rpm, MSD pulled another 2-4 degrees (depends on chip) when the last stage was engaged.

740 BBC making 1500 hp with 300/300/400hp shot of nitrous. If high gear hooks she eats 1000 shot and ------- loves it!!!!!

Lenco trans Launch, stage one is in, hit stage two before grabbing second so the slipper clutch takes the abuse and avoid tire shake, grab third and keep it straight, grab 4th and if your ***** are big hit that last button!!!!!!!!!

6.8x @ 215-220 mph

Not bad for a motor setup to run Pro-Mod in a 1990 chassis that won't hook it.

0b00st0

Lets step away from the inaccurate dial ones and stick with the digital ones.


The timing gun doesn't know ----. All it can do is relay the light at the exact same time as the spark or delay the light. They can not retard the light, thus the reason tehy are called advance timing lights.. The only way to do that would be to put the trigger on a different spark plug wire.

Racintweek

i figured it was kinda pointless to buy one with a dial because it just didnt make any sense as to how they operate. if there is no way to hook it to a crank trigger then it cant possibly know where in the crank rotation you are.




i geuss my skepticism was correct this time

krustindumm

A crank trigger provides only a few trigger points per rotation, but you seem to understand how the ECM could vary ignition timming. It works pretty much the same way. It will measure the time from one firing event to the next, and it "knows" that there were roughly 720* of crankshaft rotation inbetween. With that it can calulate the time required for 5*, 10*, whatever you have the dial set to, and delay the flash for that long after the next firing event.