Thread: Where exactly is 15* timing?

So for a long time I'm sure we've all heard that you should set your car to 15* timing. Well, also for a long time I wasn't quite sure where on the crank pulley this was(I knew where physically it was..but..well, read on) or where 'officially' 15* was supposed to be and set.

As we all know and to recap, on the crank pulley you have 2 marks that look like this:

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Supposed to be the mark to the left is 13* and the mark to the right is 15*. Now, we've also always been told when setting timing to put the pointer IN BETWEEN the two. Which would essentially be 14* timing.

So, I ask you this: Where do you set your timing? ON the 15* mark? Or between the 13* and 15* marks? Where exactly is 15*? Is 15* timing more of an idea of 'in between the marks' or is it actually to be set on the right most mark? Also, for JWT ECU's and cams they specify 15* timing but again is that ON the right most mark or between? This is something I always wondered about.

-G

I've never set timing between marks, and I don't think that's what they are intended for. Do the one on the right, the 15 mark.

If the pin is between the 13 and 15 marks, then you're right, you'd be at 14 degrees. Don't forget to look at the correct angle.

So if you were to set timing to 15* you'd set it right on the rightmost mark?

Different crank pulleys have different marks. The VE crank pulley is different from the DE pulleys. Assuming you're talking about a DE pulley, if you want 15 degrees timing, you'd want to make the pin point to the physical groove in the pulley denoting 15 degrees.



The FSM says correct timing is at 15 degrees but down to 13 is acceptable, which is why the diagram shows that black area as acceptable. You really want to be on 15 exactly.

OK that's what I always thought but didn't know if other people were setting it in between the marks and calling that 15* More of a semantic thing I guess. I don't think I'm the only one with this thinking. That being the case, there may be quite a few SR's out there that are losing some power being retarded by 1*(or more).

Playing with timing is always fun.

I have had a few JWT ECUs by now, some ask for a 25* base timing which is a little bit more difficult to get to than the 15* timing. I look straight down as if a birds eye view onto the point to be right on the groove for 15*.

I am running roughly 5* above 15* for a total of 20*-21* timing using 93 octane on the JWT ECU. For stock ECU's, I would run 5* more timing just because the stock ECU is so safe, it is not funny. (Everyone thinks the JWT is safe and it is, but a stock ECU is pathetically safe)

Here is what 15 degree timing looks on the distributor in relation to the top bolt, at least on my car

The conventional wisdom from the early days of the Forum was to go with the next to the last mark on the right for 15* (just like Ben's figure above). It was generally thought to be safe to run 17*-19* on high test fuel with a factory ECU and this was (and remains) a dyno-proven way to add 3-5 whp from mid-range to high rpm. For most engines, the power increase seen on a dyno would stop at 18-19* so there was no need to advance the timing any further.

As a couple folks have mentioned, you really need to pay attention to confirm that you are looking straight down as you line up the pin with the pulley. With an aftermarket pulley (e.g., Unorthodox Racing) it is super-important to look straight down because, since the pulley has a smaller diameter, there is a bigger distance between the pin and the pulley and a bigger chance for error if you are looking at an angle.

Finally, I would caution that the UR pulleys came in several versions with different marking systems so it's prudent, when installing a UR pulley, to set your timing dead on first with the OEM pulley, then install the UR pulley, and then check the marks on the UR pulley with a timing light and get the proper setting tattooed to your forearm so you don't forget next time you need to set your timing.