6l71 gear timing

[Me Too!]

I am using n65 brown tag injectors on a 2 valve 6l71, does the timing stay standard or should it be changed to advanced, the engine had hv7 injectors previously. thanks, Don.

[bevans6]

My tune-up guide says Brown tag N65 in non-turbo engine wants 1.484 setting and advanced timing, or 1.460 setting and standard timing and switch to advanced timing and setting at first opportunity.

Brian

[dtcerrato]

Brian (or anyone)
We too are running the n65 brown tag injectors on a 4 valve 6I71
We are at 1.460 setting & standard timing (recommended by several bus nuts & after a recent in frame rebuild)
What does the last part of your sentence mean - "and switch to advanced timing and setting at first opportunity"?
Thanks
Dan

[bevans6]

It means that running 1.460 injector height advances the injection event of the injector somewhat but leaves the valve timing the same.  I don't know how much the change in height advances the injection event compared to a tooth on the gear, but intuition says it doesn't advance it as much.  So you end up with a late injection event and possibly late valve timing, and DD determined that it was off enough to strongly recommend that the settings be brought back to spec.  In other words, just going to 1.460 wasn't the performance equivalent of advanced timing and 1.484.  The issue as I understand it is that the specific design of the brown tag injector internals is what creates the retarded injection event.  Apparently white tag N65's are designed to run with standard timing and 1.460 setting.  Brown tag N65's run standard timing in a turbocharged engine that has increased cylinder pressure from the turbo.

In the "rule of thumb" category, advancing an injection event creates an earlier combustion event, more cylinder pressure, more combustion heat, and more power.  Retarding it does the opposite, and can create incomplete combustion and black smoke earlier.  Like all rules of thumb, this is taken with a grain of salt.  If you buy a power chip for your F250 diesel, you basically get the timing advanced and the fuel curve enriched, and you have fun until you blow the head gaskets...  In two strokes you melt the pistons with too much fuel and advance, or so I have been told.

Edit:  advancing the cam would move all cam events a few degrees earlier in the stroke.  So the exhaust valves would close earlier, which would start the compression process earlier, which would increase the dynamic compression, which would increase cylinder pressure after the injection event, which would match nicely with the increased fuel from the larger injector, which would increase power.  I think, anyway.

[luvrbus]

Don't worry about A timing or the N65 injectors just install 7E65 injectors set at 1.496 or 1.500 the 7E65 injectors have the timing built into the injector.
DD hasn't A timed a automotive engine since 1980,the 7E65 burns cleaner,more power,more torque with better fuel mileage than the old N65 injectors fwiw.
I never A time a 71 series when one comes in with A timing I change it back to std and install the 7E65 injectors.
You never see a 92 series with A timing it is done by the injectors 

[bevans6]

Injectors are $160 each rebuilt (no core) or $265 new.  $1600 for a 6 cylinder engine!  Adv timing is free!  I'm Scottish and cheap...      

[luvrbus]

Injectors are $160 each rebuilt (no core) or $265 new.  $1600 for a 6 cylinder engine!  Adv timing is free!  I'm Scottish and cheap...    

I pay $55.00 ea exchange $20.00 core charge, the $160.00 is a little steep for me too and I am not Scottish  .I wouldn't pull the back off one for 400 bucks 

[bevans6]

To be honest, and having done it, I probably wouldn't pull the back off one for $1600!  Definitely totally not if it started and has to end in the bus!   

[Me Too!]

looks like I will go with standard timing and n65 brown tag injectors at 1.460 setting, only because I already own the n65s, will try the 7e65s if I need to. thanks all, Don

[dtcerrato]

You hero gurus dish that knowledge faster that we can digest it.
The 7E65 injectors sound interesting.
Don't know if you'd feel any difference at the seat of you pants though, would ya?