As some of you already know, I have an 87 that is my daily driver, and an 86 that I will be selling soon. The 86 has rebuilt injectors, and a rebuilt ip all in 04. I was considering switching them out with the ones on the 87. (the ones on the 87 appear to work fine, but are 19 years old instead of 2) How accurate is static timing? Will static timing only work if you are taking the ip out of and putting it back into the same truck? Otherwise, I have an inductive timing light from a gas car. This will not work with a diesel though right (It has a +, -, and a clamp that goes on the spark plug wire to tell when the spark passes through)?
If I switch out only the injectors, and not the ip will I still have to adjust the timing?

Thanks,
Kyle

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87 F250 6.9 daily driver, xcab, 4x4
gathering parts for wvo conversion.

86 f250 6.9, xcab, 4x4, plow

 

Static timing is only accurate enough to get one running so that you can do the dynamic timing. Even if you marked where the existing pump's timing mar is, and put the new pump in aligned with that mark, the odds are probably 100 to 1 against it being right. The timing marks are done after the pump is timed at the factory and no two are exactly the same.

The timing light you have will only work if you have a pulse adapter that clamps on the #1 injection line to sense the fuel pulse and then translate that into an electrical signal for your timing light. These pulse adapters sell for a couple of hundred dollars.

If you change your injectors, it will probably change your timing since the old injectors have weaker springs (from cycling millions of times) and therefore "pop" (spray fuel) at a lower pressure than the newer ones would. That means that they "pop" a little sooner than the new ones would - so the timing would probably need to be advanced a little to compensate if you installed the new injectors.

New injectors on an old pump is not a good idea anyway. Because the new injectors will take more pressure to make them "pop", it will put additional load on the pump and, given its age, probably cause it to fail in pretty short order. Pumps and injectors should all be changed at the same time as a set.

So, if you are going to change anything, swap both the pumps AND the injectors between the two motors, then either get a pulse adapter, or take it to someone who has one, and get the timing reset on both motors. Of course a diesel specialty shop will be the only ones who have the pulse adapter and know how to use it. Most decent shops can re-time a motor in just a few minutes. Heck, Spectramac and I did mine in a parking lot in about 15 minutes. If you take both trucks in at once and talk real nice to them, you might be able to get them to do both motors for whatever their one-hour minimum charge is.....