i think i got it worked out but want to make sure. instead of a trigger it has a dial that you turn which turns a wheel with numbers on it. i think you set the # of degrees you want BTDC in the middle of the display. then there's a switch for either 4C or 2C, this should be set to 4C for 4 cycle, right? then when you actually use it you want the timing line to show up at zero degrees on the tab when the dial on the gun is set to the amount of degrees advanced you want.

 

Sounds right to me.

 

Yes.

 

Can't get nothing by you, can they?

That's exactly right.

The great thing about those guns is using them to check your timing curve AND total advance.

Of course if you're using EST, then it's arbitrary. My car (TBI) shows 44* total advance in "Park" while it's not under a load. That's a lot!! I seriously doubt it ever reaches that much under load ... although it's nice to know it CAN advance that much if necessary.