Injection pump timing

[John Scott]

So I bought the Rotunda from John Scott (thank you very much John!!!). I hooked everything up and got a reading of 2.5, with setting it at -20 before startup. Am I just that good at setting my timing by ear or should I be concerned that there's no way I'm that good? The directions mention being negative over positive. I'm confused....

Thats awesome... well I felt the same way when I set mine up with the rotunda and when I hooked up the pulse meter it was dead nuts on 8.5 btdc. U start with a neg 20 but end up with a positive 2.5... great job... we both did good... lol

 

[William workman]

Hi Guys ! I'm new to this way of trying to get things done . I've got the old 1985 6.9 non turbo engine . When I bought this truck ( F-350 dully standard cab ) It had set for 5 years not running because of the good old biodiesel fuel . I have replaced almost everything in the way of fuel . I got a rebuilt pump and installed it with the timing marks on engine . It stars and runs good . Now I have the Rotunda 78-0100 Tach/Timing Meter . I'm trying to figure out how to use this Meter ? I don't know what I'm looking at or what I should see using it . I do as the instructions say to do to set it up . After everything is hooked up as it should , I set the offset angle to -20 .Start engine bring RPM up to 1400 . when looking at the offset it now shows -13 ? Can anybody tell me what I'm Seeing and what it should read .
Regards
Bill

 

[William workman]

How complete the meter is will depend on the instructions given. I have the same problem but. Here is what I found. The meter has the simple positive and negative cables that you connect to the battery. The white wire is the piezo plus and it connects to the # one injector and a near by ground. The next is the magnetic pickup with what looks like an old Briggs & Stratton pull start handle. That connects to the box that has "use with 7.3 motor" on it. Also on that box is where the plus white wire connects. Now connect the box to the meter and install the magnetic pickup in the tall tube at the dampner. Make sure its very close to the dampner or it wont work. I was advised to keep it 1/16th inch from the dampner. Try to get it closer but not touching it. Now set the offset on the meter to -20 degrees. Start the motor and have the rpm at 2000. Check the reading where the offset was and it will tell you what the advance or retarded degrees is. Be sure to trun off the motor when you advance or retard the timing. Otherwise the injection pump will turn by itself and break something. These pumps have plenty of force going on in them trying to turn them if things are not tight. PS... Those 3 nuts are hard to reach and must be tight when your done but not so tight that they break off. The small 5/16 bolts that hold the gear to thepump torque is 25 lbs. Be sure to use the correct socket. Somelike the 8 mm socket. Id your truck an auo or standard trans?

This is from icanfixall.

Thanks ! My truck has the C6 automatic . Ok so if I got this right ? I have my 6.9 running at the specified 1400 RPM the offset set at -20 degrees ,and that it running now the offset shows -13 dose that mean I need to back my pump back ( 9 degrees ) to where it will show - 4 degrees ? That's what my specks show for Cetane Value 50-47 . I don't know why the instructions for the Rotunda 78-0100 couldn't tell a little more about what to see in the degrees display box . I hate to be so dumb here but I guess if it was simple everyone would be doing it . If this is wrong please let me know .
Thanks Again

 

[John Scott]

So start off at -20 with engine off ... start engine and adjust the IP to passenger side until meter is 2 to 3 degrees positive.... thats equates to 8.5 to 9 degrees btdc.... also for every 1/8 inch from static timing equals about 4 degrees... in my opinion... hope this helps