Thread: JWT S-series cams and ignition timing questions.

I've been driving around lately with my ignition timing set at 10* for nitrous. Well today I decided to advance it again to 19* which is what I had my ignition timing set at with my stock 98 cams. I want to compare mpg difference from 10* to 19* timing.

I remember reading somewhere on this or the other forum that the S series cams (s3,s4,s5) do not "like" any more timing than 17*. When I texted a friend for the timing procedure he also told me about the timing ordeal. So my questions are

1. What does it mean when people say the cams do not "like" timing above 17* ?
2. Am I hurting the motor with my S4 cams and ignition timing set at 19*?
3. What are the drawbacks of my ignition timing set this high?


Thanks for all and any input. Sorry if its hard to read but I'm posting from my phone.

If JWT ECU, they are normally programmed for 15 deg base timing.
If stock ECU, per FSM you are good with 15+-2 degrees. If >17 then run premium/93 octane to be safe.

I have S4 cams w/ JWT ECU, 15 deg base timing.
Always run 93 octane, no ethanol if available.
39.6 mpg today on 130 mile trip per ecutalk display.

I have no idea what they mean, but I'll tell you one thing you should know. The more air/fuel you have, the faster it burns. This means that when you put in higher flowing cams you're going to have more air and more fuel to burn. This mixture will burn faster than the mixture you had before the cam. This means you don't have to ignite it as soon to get the best power from it.

Same reason you need to retard timing with Nitrous, only to a lesser extent.

jp314 has the right idea. If you have a JWT ECU, keep things at 15 degrees. If you have a stock ECU 19 degrees is your best bet with stock cams. I would go down to 17 degrees or maybe less with the S series cams depending on which ones. And run the best octane you can.

Possible loss of power and/or detonation.

Cool. I will back it down to 17*. Im running S4s BTW.

Today I was driving around with 19* timing and it didnt seem like it was detonating.
My spark plugs are NGK BKR7E so maybe thats why I didnt have symptoms of detonation?

Thanks JP and Ben.

Spark plug heat range doesn't really have anything to do with detonation, only pre-ignition.
The chances of detonation are unlikely, but possible which is why I mentioned it.
Also the stock ECU is good at backing off timing when it gets even a hint of detonation. (Not that you should rely on that.)