My truck WAS a CNG but now is just gas. I get spark knock underload. Prioir to doing a timing test (later today) I just wanted to ask.

Does anyone know if you need to change the timing when converting to CNG???

Thank ya for reading.

 

hello, still need help.

 

Hello bro, when running on CNG your timing must be advanced between 8 and 10º, I hope this helps you. But if you are not sure please go and see a mechanic, don´t want to see you blow, haha. Good Luck