DETROIT 671 INJECTOR TIMING

Phil H

Member
I hope this is the right forum, because it seems you folks talk Detroit Diesel. I was wondering how critical is the setting on the injector, using the timing tool. My injectors are to be set at 1.484, and I was using a dial caliper at first, to set the height of the injector follower. It never seemed to be consistently accurate, so I got a real Detroit injector timing tool and will use it to see if things work better. It seems even using this tool that there is some room for each injector to be slightly different after setting. So, just how critical is this setting???? It seems to me that the more critical setting is the rack adjustment on each individual injector. To make sure each injector opens fully to get the most fuel in at each throttle setting, and equal amounts. I know they both work together on a tune up, but what is the most important? I have never set an injector in my life so that is why I am asking. Thanks....Phil
 

Injector night is about the timing of the injection event, not volume.
Timing and thus height depends on 2 or 4 valve, piston dish size ,sleeve port height , altitude, blower speed, turbo boost and intended rpm operation range.
Emissions engines tended to retard the injection event to reduce NOX.
 
Thanks, from your comments I can see that this works, and I think the closer to the perfect setting the better. What do you think about the setting of the rack it self. Seems like this is the fuel you are getting in to the cylinder, and trying to keep it equal for each cylinder to generate the same amount of power.
Thanks.....Phil
 
I looked and my tool just says 1.480 I have set without it and went for 1.500. Ran the same. Setting the rack takes time and nerves of steel. Run it and be sure it is the same. Also unhook every injector and be sure it will go wide open. Also cannot bind. Go back to shut on tbere own. Speed secret bump the cam timing up a tooth.
 
Thanks, don't know how to bump the cam up a tooth. Just want my truck to pull hard like it use to, before I replaced no.1 injector. I think I may have moved the rack adjusting screws, and that is probably why it doesn't pull as hard as it should. How hard is it to bump up the cam? How do I do it, and does it get more HP if I do????? Thanks for the Help.......Phil
 
Your rack needs to start moving all in at once. And get them all open at once. Also needs to be in gov range. One tooth on cam gives it more low end. When you are holding rack wide open. Take a screw driver and push down on the square part. It should rotate and then come back. About 1/16 turn. When get all there will run sweet. If all are moving all the way open
 
Thanks,
This is my first time doing this, but I do have the books on the 671, so trying to learn all I can. If I can just get the old girl (72 IH. 10 wheeler) to run like it should, I will be happy. Sounds like changing the cam a notch would be a REAL BIG DEAL. Thanks for your help.....Phil
 
Sounds like you have been there and done that. I just hope I can say, I got things to run right. Thanks....Phil
 

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