Sideflop Posted December 1, 2019 Share Posted December 1, 2019 Is it possible to make a 6k RPM tach work on a diesel? And will it read correctly? Link to comment Share on other sites More sharing options...
85lebaront2 Posted December 1, 2019 Share Posted December 1, 2019 Probably not, the Diesel tack is triggered from the teeth on the injection pump drive gear, 105 teeth so it is an odd number of pulses, gas engine uses the coil - terminal for it's source. Link to comment Share on other sites More sharing options...
Ford F834 Posted December 3, 2019 Share Posted December 3, 2019 I read a post from a guy who swapped an IDI into a gas F150 and he hooked up the gas tach to the diesel sensor. He said it did read, but he didn’t think it was correct. He didn’t mention by how much, or if it was higher or lower than expected. Since the IDI is governed at about half of the 6K’s sweep, it’s not a very desirable tach for that engine anyway. You really need the 4,500 rpm with the yellow and red zones for the 6.9 IDI. The diesel tachs from the medium duty F600/F700 read flywheel teeth and shouldn’t read right either. Link to comment Share on other sites More sharing options...
Ford F834 Posted December 3, 2019 Share Posted December 3, 2019 I don’t know if you are aware, but the 83 & 84 diesels did not have the tach option. The injection pump gear housing does not have the threaded port for the tachometer sensor. There is no wiring for it in the harness. I looked at the pics in your build thread and yours does not have it. You can still add a factory tach, but it isn’t plug and play like the 85/86 trucks. You need to supply the wiring and you need a late 6.9 or 7.3 injection pump gear housing with the port. You also have to know how to remove the housing without getting the engine out of time. It’s not that bad, you just need to be aware of it and it is an involved project. Link to comment Share on other sites More sharing options...
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