Hi, I just bought a company truck. An 86 F150 xlt lariat with a 4.9L and 165,000 miles on it.
It runs good but I think the timing is off. When starting, the engine spins over very fast but smooth before it starts. This leading me to believe that the timing is way slow (retarded). I checked the timing and it is set at 10º BTDC. However I'm wondering if the timing was set using the correct mark. The mark is a very faint scribed line in the dampener but about 3 inches over is a notch in the dampener but I think that is for electronic timing???
The truck runs kinda OK with no oil consumption but I only get 13 MPG.
If that is the correct mark is it possible that the dampener has rotated on the hub???

 

Oops, yours is an 1986.

http://autorepair.about.com/library/faqs/bl906.htm

 

I doubt the thing rotated. Clean off the litte tab w/ the timing marks on them. you should be able to see the numbers. But before you do that, start simple. Did you tune it up? You should be doing much better than 13 MPG.. Start with new cap, rotor, pcv valve and plugs if you don't know when they were last replaced. If you still have the problem, try a new set of wires. If that fails, then put a timing light on it.
Do the fuel filter while you're at it, and replace the motor oil, tranny, xfer case, rear end and front end fluids and grease the chasis. This is a company truck and probably driven hard (not necessarily abused!). Hope this helps. good luck.

 

I agree with Jimsa, mechanical timing rarely changes once it is set.

 

OK gents. Thanks. I do however know it has recently been tuned up... I have a print out of the maintenance records. That's what lead me to believe that the timing might have been set and probably set to the wrong mark. I will read through the recent records and see just what has been changed.
Again thanks for the information.

 

Just a quick question but did you remove the single wire inline spout before checking for 10 deg BTDC?

 

Yes I did disconnect the single wire at the dist. before ck'en the timing.
But now I know there is something wrong because I bumped up the timing to 12º BTD... (two degrease) and my fuel mileage went from 13 to right at 14.5 with no pinging that I noticed. I think I could go a few more degrease but am afraid to until I figure out what's wrong.