Fuel Mileage VS Timing

[justinray]

It's just 8 lines, and 8 injectors, takes an extra 20 mins, and gives you something to do while the oil is draining.

 

[PwrSmoke]

I can only report anecdotally but after Mel set mine to 9.5 (from about 7.5 or so) I noticed more noise, more snap in off-idle acceleration performance, and a slight uptick in mpg. I can't give you a number yet, but I'm tracking it. I drive this truck so seldom these days that it takes a while to generate averages. If I was forced to guesstimate a number, I'd say it's under 1 mpg... which makes it more or less within a margin for error and will take a looooong time to average out a good number, if I ever can.

 

[HammerDown]

I can only report anecdotally but after Mel set mine to 9.5 (from about 7.5 or so) I noticed more noise, more snap in off-idle acceleration performance, and a slight uptick in mpg. I can't give you a number yet, but I'm tracking it. I drive this truck so seldom these days that it takes a while to generate averages. If I was forced to guesstimate a number, I'd say it's under 1 mpg... which makes it more or less within a margin for error and will take a looooong time to average out a good number, if I ever can.

With my timing set to the same degree...I got all the above except slightly worse mpg

 

[Kalashnikov]

I put my 40s back on and it seems to be pulling better up hills but I still have quite a bit of throttle slug. It I give it too much throttle it acts like it's starving for fuel. Still getting a lot of black smoke too, hard to tell if it was happening with the fuel starvation since it happened tonight. Hopefully ordering a ferret soon.

Just blew a ujoint and tore the ears off both axlehshafts so I'll add that to the list.

 

[RLDSL]

at 8.5 when they changed the fuel to teh ULSD my mileage and power went in the toilet. Set it up to about 9.7 and picked up about 4+ mpg and the power went back to where it used to be at 8.5 on the old fuel. fuel mileage and power when related to timing are a double edged sword. you set the timing up to where it runs good, then it runs good and now all the sudden your right foot gets an itch in it, next thing you know, yer ******** about crappy fuel mileage ??? I spent about 1.5 million miles in a big truck where every drop counts, and I know how to keep that little itch under control, so magically my mileage goes UP along with the power when the timing goes up . It's called volumetric efficiency. , when its running good, you use less fuel to get there... you just have to learn not to enjoy it so much

 

[FORDF250HDXLT]

I put my 40s back on and it seems to be pulling better up hills but I still have quite a bit of throttle slug. It I give it too much throttle it acts like it's starving for fuel. Still getting a lot of black smoke too, hard to tell if it was happening with the fuel starvation since it happened tonight. Hopefully ordering a ferret soon.

Just blew a ujoint and tore the ears off both axlehshafts so I'll add that to the list.

i believe she's starving for more air,not fuel.

 

[tanman_2006]

This is true, if finances allow, I find it best to have injectors pop tested every other oil change, and reset timing. It really isn't that big of a deal, and I find that IP's and Injectors last longer, and I get much better mileage, so it pays for itself in many ways over time.

For some people that is new injectors every month. Sorry but on a 6.5L no one would ever do that, I takes 2-4hr to get to the injectors normally.

I guess if we changed them once a month then our turbo wouldnt be siezed to our manifold as bad and pulling our inner fender wouldnt be so awkward. Practice makes perfect.

 

[Black dawg]

For some people that is new injectors every month. Sorry but on a 6.5L no one would ever do that, I takes 2-4hr to get to the injectors normally.

I guess if we changed them once a month then our turbo wouldnt be siezed to our manifold as bad and pulling our inner fender wouldnt be so awkward. Practice makes perfect.

You can change those injectors without pulling the turbo.....it isnt as bad as you would think.

 

[tanman_2006]

Looks pretty bad too me. Ive pulled 3 sets and never was patient enough to make it work with out yanking the turbo.

 

[Black dawg]

Just gotta be careful that your socket doesnt get crooked on the injector and bend the return nipples. I have yet to pull the turbo to do injectors on one..... I guess I am lazy.

 

[justinray]

Ive never pulled turbo or anything for injectors, but I've never worked on a 6.5

 

[79jasper]

Ive never pulled turbo or anything for injectors, but I've never worked on a 6.5

The injectors and glowplugs on the gm 6.2/6.5's go in where sparkplugs would be on a gasser.

On the turbo models, they use a different passenger manifold which the turbo sits on. So it blocks some stuff. My 82 red block has longer injectors which would interfere with the manifold without modification.

Maybe one of them can post a picture. If not, I'll find one.

 

[Kalashnikov]

i believe she's starving for more air,not fuel.

Now that I think about it, if I get to a certain point in the pedal I get fuel starvation and no smoke at all. When I back off I get a big increase in power and a little bit of smoke. I think it's when I go past the dead spot it just dumps fuel like crazy and blows black smoke. There might be a little bit of excess fuel dumping right before the "nice" spot when I start to back off the pedal as well.

IMO pulling injectors every other oil change seems like a waste. They are cheap enough to just replace when the time comes. I certainly don't have the time to pull them that often when there are plenty of other things on my to do list.

 

[justinray]

Now that I think about it, if I get to a certain point in the pedal I get fuel starvation and no smoke at all. When I back off I get a big increase in power and a little bit of smoke. I think it's when I go past the dead spot it just dumps fuel like crazy and blows black smoke. There might be a little bit of excess fuel dumping right before the "nice" spot when I start to back off the pedal as well.

IMO pulling injectors every other oil change seems like a waste. They are cheap enough to just replace when the time comes. I certainly don't have the time to pull them that often when there are plenty of other things on my to do list.

It's not completely necessary, and I'm not saying everyone should do it, but I do believe I get better mileage because of it, and better performance, and it keeps me from getting a washed out cylinder from a drooling injector.

 

[Agnem]

There is no substitute for proper timing. Keeping your cruise RPM's at 1800, and having a good pump with good injectors, and a manual trans is the key to good fuel economy.