I've been dicking around with my timing some to get a good mix of power and mpg. When I first got my rotunda pulse meter I was at 15* btdc. Didn't have an egt gauge at the time so who knows where those were. Anyway set timing to 8.5*. Truck felt sluggish and my mpg dropped from 19-20 to around 15. Much quieter engine tho. No black smoke under full throttle or load. Soooo I have the timing at 12* btdc now. I turned the fuel screw down a flat. Now I have a noticeably stronger pulling truck an my mpg is going back up. Only thing I have any concern over is the engine when cold is waaay louder than before. When the cold idle advance goes off and the engine is warm is not much louder than before. It's not as clackety as when it was at 15* but just thought I'd ask if I'm risking tearing anything up. Like I said I turned the fuel down just a little to avoid building too hot a fire and my egts are still safe. I do get a bit more black smoke under load or at full throttle but that's it. So will I be safe to stay where I am? Thanks
Timing for best power and mpg
- Thread starter heff
- Start date
icanfixall
Official GMM hand model
Turn down the timing to max 10.5 dbtdc. Your really hurting the engine running 12 to 15 degrees advanced. I like 9.5 advanced for what I do and its been found that 10.5 is about the limit before damaged to the glow plugs happens. But your running what feels good to you. What I just posted has been tested many times in this forum. Others will chime in on what they have found to work.
justinray
Contributor
^yes.
jaluhn83
Full Access Member
Too early of timing means the piston is still on the upward portion of the stroke when the pressure wave hits it. Ideally this should happen just as the piston starts moving downward, that way you get smooth transfer of force. If it's too early essentially the piston/rod/crank is solid (doe to being at TDC - like jumping with your knees locked vs knees bent) and you get a huge shock load - very not good for the engine.
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