Truck Running Differant @ 9.9 DBTDC
- Thread starter icanfixall
- Start date
Ol' Smoky
Registered User
I sure would appreciate if someone knew the exact number where it was best, its been mostly a guessing game for me
When adding fuel and boost in the quest for better performance, a key component, timing, is often overlooked. Timing mechanically injected diesels is simple in practice, but understanding the why and where to time is what this article is all about.
"As always, there is a happy medium between fuel rate and ingnition timing. A general rule to follow, and a good starting point for tuning, is that the more fuel you're running, the more conservative the ingnition timing. It all goes back to cylinder pressure. Adding fuel increases the combustion pressure since there is now more gas trying to expand rapidly during the power stroke."
from the looks of it it seems each engine lokes something different! when they were new it makes sense for it to be one timing for all, but as things wear perhapd they need different timing?
IMO EGT are the best way to tell which timing is the best.
Logic tells me that, at least with an n/a. lower egt is better.
if you have 300f at 6*, and 200f at 10* you are using the heat better to push the piston down with more force.
That OR the cylinder walls are exposed to the heat longer and it goes into your coolant.
IMO EGT are the best way to tell which timing is the best.
Logic tells me that, at least with an n/a. lower egt is better.
if you have 300f at 6*, and 200f at 10* you are using the heat better to push the piston down with more force.
That OR the cylinder walls are exposed to the heat longer and it goes into your coolant.
xcite
Registered User
One thing that makes it hard to say all engines should be at a specific timing is you would have to assume all the parts between engines where the same. The marks on the balancer could be off either in manufacturing or have moved in there rubber mounting causing it to require a different reading to be equal to another engine. The list is longer when you factor in differences in gears, wear patterns, keyway locations, ect. The only way to know for sure where an engine like to run is to test it out at different timings and check performance and mpgs ect. to determine where it is best to be ran at. All that can be guarenteed with a spec timing is it should run decently and not cause damage but if you trully want to get peak performance and milage from your engine it will take testing several different settings to finally get it where you want it. Thats is why you will see some engines are set at 8.5 for an example and others end up being 9.5 or some other number. For example if I set my truck to 7 it sucks fuel moved it to 8.5 and got alot better and will be moving it up some more for the trip home to check if it improves any more or not till I have it dialed into where I want it. All this is done to balance performace, economy, and durability of the engine, egts are part of the equation that you look at to see if you are headed in the right direction or not.
ideally you would want to be on a dyno, with an egt gauge and an accurate graduated cylinder with say 1 litre capacity, hooked up to the injection pump to see where your engine is happiest. Ideally you want to shoot for max power, as that is when your engine is working most efficiently. Assuming EGTs are kept in check. Mileage from a diesel comes from a light right foot.
icanfixall
Official GMM hand model
Most of whats posted is correct. Where I don't see much agreement is the dampner machined area and the gear wear changing the timing. I'm sure those are possibilitys but not probabilitys. I did some extensive mearureing on my new and old injection pump and cam gear. The wear was not a significant amount to measure. The only reason I changed my cam, gear and thrust was I had a new set and wanted the new cam gear thats balanced much better than the old gear with the drilled and threaded holes in it. Any time we change the injection pump or the injecters these engines require being timed. This is an agreed job by most in the know. This I have learned and verified many times. Mel at Conestoga Diesel was a big help in this information. Many have benifited from his timing clinics at the last 13 years of rallys doing the timing of what ever got driven or dragged to a rally.
Well if anyone does give you a definitive answer it best be the FACTORY spec and that alone, otherwise, they be blowing smoke up !@#$!@#@#
These engines do and can use a range of timing and that is dependant on many things and two not mentioned and need to be considerate of are, climate...HOT HUMID climates are different from cool ones, and altitude as well.
However Altitude is likely a much larger part of the timing picture than average tempurature.
Many here have said what they run and that being from 7-11 is a 4 degree range. Break that down into tenths of a degree, which can be done with Gary's meters and others whom have one and that 4 degree range takes on a large accurate part.
IMHO and that is just what it is, not trying to blow smoke up....well you know what I mean, My suggestion is start first by determining what you are currently running at, and if low the go around 8.5, and likely you can go up to 9,5/6ish safely.
Any more than that and there are some thoughts on glow plug tips burning off from the length and heat, however if your egt's are lower then I am not personally understanding that belief.
Clearly there a variety of thoughts on where timing should be. I've given you mine, and from what my timing was 7.4, to where it is 9.6 I picked up some power from my AZZDYNO accordingly. It runs better I've got great mileage too 19 MPG + not bad for 4:10 ZF5 1ton 4x at 130-140 KMH mixed with city driving.
You will likely find a "sweet" spot that you can run and get power/mileage that works for you.
Take what you want from the thread and leave the rest...
good luck
Ol' Smoky
Registered User
The other thing to think about is how these pumps work. The beginning of injection depends on how much fuel is metered into the pumping chamber. If there is any fuel restriction, then not only will less fuel be injected, but the timing will also be retarded. I checked charging pressuse of the vane pump on the back of the pump and it was 50 PSI at idle and 110 at WOT. To the best of my knowledge that is about where it should be.
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