I have an '89 4.9 L F-150 that was not running great, so I replaced dist cap, plugs and wires. I then attempted to check the timing and was unable to get it to time at 10 BTDC (looking at the marks on the left side - spout connector disconnected) I have since played around with the distributor to "tweak" the timing and it has become difficult to start and the plugs are now fouled. I replaced the Throttle position Sensor and plan on installing new plugs, but am still faced with the issue of the timing being off. Cap and wires have been checked several times 1-5-3-6-2-4 and #1 wire is connected where the 1 is on the cap. Can anyone suggest any sensors that I may need to check or any next steps after I made adjustments to the distributor?

 

I know this is a dumb question, but are you sure your timing light was connected to the #1 plug wire? I once adjusted the timing on my 5.8 with the light accidentally hooked to the #3 plug wire and you can imagine that made my truck run like crap.

Otherwise, is 10 BTDC factory setting? If not try resetting the timing to factory and see what you get.

 

Yeah, the Timing light was on the #1 wire and 10 BTDC is on the label under the hood. I do remember connecting to the #5 wire once and the timing was near dead on. Looks like I'm paying for "fixing something that won't broke."

 

I guess I'm not really understanding why you weren't able to get the motor to time to 10 BTDC. Was it killing the motor? If so it sounds like there's been some mods to the motor that will prevent it from being able to be set at factory.

 

my straight 6 wouldn't line up either.
I eventually just hooked the timing llight to the coil wire
to see if ANY spark was hitting tdc or 10 btdc

Now I do remember some vehicles where the timing pulley will actually separate from the inner core.

There's some vulcanized rubber that holds it together.

anyway, I eventually adjusted it by ear.

Turn the dist, start it up, stand on the brakes and rev it up to hear it ping, back off the timing, try again and agian and now it only pings under
irresponsible acceleration.

But where do you start? say if you pull the dist without marking it first?
with bad crank timing marks?

Pull #1 plug, put in a plastic drinking straw and rotate the engine with a wrench until the straw tells you it's at the top and hope it's the ignition stroke.

Easier if you can see the cam timing marks or cam lobes.

 

If you have a compression gauge, you can also hook that up and use that to tell you when it's at the top of the proper stroke. Just turn the motor over until you see the gauge jump. It can be kind of tricky- I ended up turning over my motor a few times and timing it just right to quit turning the key, but it worked. That allowed me to get the distributor installed "close enough" and I was able to time it from there.

 

That is a really good point. It is not that uncommon to have the harmonic balancer slip on any of these old vehicles. It would be a good idea to use the procedure described above to verify if this is the case.