Crank Timing

[Nettlez]

Just a quick one, so I have just got the car together with its new engine but it’s not running right, hunting on idle and stalling when the revs drop. It’s got a 3.0 crank (was a 2.8) and 1.5mm over bore making it’s a 3.15l, exhaust cam on the intake. So I want to check the base timing but I seem to remember it being a bit of a pain to do a zero. So it’s a Bmw m50nv engine and the crank settings are 60 missing 2, so does this mean that each divot on the wheel equates to 6 degrees? So an easier number to used could be 12 so two divots before?

[cj]

your trigger 1 settings have to match what is actually on your crank. If you have 60-2 (58) teeth and you configure it for 12-1, it will think its running at 5x its real RPM, and will be firing injectors and ignition all over the show. It would be a very bad thing.

To set base timing, all you need is to know the crank and cam trigger patterns (60-2 for crank), and whatever the cam tooth count is. You also need a timing mark on the crank and mark to match it on the block - likely somewhere between 0 and 15* BTDC. You need to check the manual or somehow find out what number of degrees your timing mark is at.

Then you disable spark+injectors, put that number of degrees into the first field in trigger1 calibration screen, and crank away while adjusting the offset.  Only way any engine can be a "pain" to set is if the timing marks are in an awkard place to see them, or if there are no marks on the crank. In either of those scenarios, i'd set the engine to TDC or the 10/15 deg mark, and make a new mark on the crank and block in a more reasonable position.

[Nettlez]

Yeah it has a tdc  so 0 degrees mark so I have marked that underneath onto the sump and wheel so I can see it with the light when it’s running.

So I was trying to figure out how to mark 10 degrees on the wheel so I can make that mark on the wheel too so I could check it with it running rather than just cranking? 

[Adamw]

5 hours ago, Nettlez said:

So I was trying to figure out how to mark 10 degrees on the wheel so I can make that mark on the wheel too so I could check it with it running rather than just cranking?

 

You can get a reasonably close 10deg mark on the pulley by measuring straight line distance from the TDC mark.  Circumference of a circle is dia x Pi.  If we divide the circumference by 36 then we will have the "length" from TDC to the 10deg mark.