1990 f150 5.0 4x4

Where am I suppose to set the timing to? at "A" or "B"?
Also it's suppose to be 10* BTDC right?

I currently have 10*btdc set at "A", but when I start it, it starts hard like it's too advanced.

 

Are you trying to do the timing advance mod? If so start at 20 degrees and work towards 10. Not all engines are the same and sometimes you can not get to 10.

 

I'm just trying to set my base timing.

 

What year and motor?

 

Also did you pull the SPOUT plug?

 

Pull out the spout plug, and 10 degrees advanced which is the stock setting is at the center of the largest pie wedge cut out of the timing plate. Also, don't use the large notch on the pulley to mark timing, it is the smaller groove line on the pulley. Once you adjust it, tighten the distributor back up snug and recheck it, and if its good, then shut it down and plug the spout plug back in. That's it. And I would disconnect the battery and reset the computer after messing with the timing too. You might not need to, but I do it anyway.

 

Looking at your diagram, it looks like A is the base timing position I was talking about. B is wayyyy retarded timing. Note: this is not an insult. haha But since you have a red and blue mark on your pulley, make sure you're using the right mark.

 

Quick answer:"B"
You are way too advanced/ Surprised it starts/ If in fact, that's w/ Spout plug removed/ Geese, looks a little scary even for the Spout plug in!

This shows 13 BTDC Base timing. W/ Spout plug removed (A nice little base time bump):




Base timing is w/ the Spout plug removed. Any base timing change is done w/ Spout plug removed.

W/ Spout Plug in place, that is "Base timing" plus ECU advance (Probably 7-9 additional degrees at idle/ 20-23 additional degrees added w/ additional ECU advance "all in". "All in" being the top end of the timing advance curve.

 

I just noticed this is a 5.0 not a 4.9. But for mine base timing is the middle of the large triangle cutout on the timing plate. I think it would be the same on the 5.0 but now I can't verify that, as the plate may be different.

 

The I-6 is very different.