Tachometer Interchangability

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Tachometer Interchangability

Sideflop
Is it possible to make a 6k RPM tach work on a diesel? And will it read correctly?
1984 F250 XL with International 6.9L IDI, Borg Warner T19 transmission and Borg Warner 1345 transfer case. Still has twin traction beams.
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Re: Tachometer Interchangability

85lebaront2
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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.
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"Getting old is inevitable, growing up is optional" Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 1994 Taurus LX Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Tachometer Interchangability

Ford F834
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In reply to this post by Sideflop
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.
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 SRW under construction-- 7.3 IDIT R&D 64mm intercooled turbo 150cc IP stage 1 cam main girdle 13" Southbend clutch ZF-5 + GearVendors overdrive 4.10 axle gears hydroboost brakes

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4 conversion-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering
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Re: Tachometer Interchangability

Ford F834
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In reply to this post by Sideflop
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.
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 SRW under construction-- 7.3 IDIT R&D 64mm intercooled turbo 150cc IP stage 1 cam main girdle 13" Southbend clutch ZF-5 + GearVendors overdrive 4.10 axle gears hydroboost brakes

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4 conversion-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering