Got weird one for you guys...

A couple weeks ago I noticed a slight miss in my F150. All of the ignition components are new, so I pulled out my timing light and decided to verify timing was 10 degrees BTDC, like the sticker under the hood calls for. I started by disconnecting the spout, hooking my timing light to number one, and looking for the timing mark on the balancer. Well, it was nowhere to be seen, even with it being cleaned and marked with white paint. Thinking the timing light was out of whack, I tried another with the same result. Next I turned the motor over by hand so the balancer indicated TDC on the timing marks and popped the distributer cap. Now this is where it gets really weird, the rotor was pointing to number four. So I rearranged the plugs so that the rotor was on one and double checked the firing order. When I went to start the truck it would half way turn over, stop, then repeat. I knew what was happening, it was firing way too early. Still puzzled, I put it all back together the way it was before, got it running, and hooked the timing light up to number four. Sure enough, I could see the timing mark on the balancer now using the timing light. Timing wasn't steady either, very erratic.

So now I can only guess that the timing set is not only lose, but it jumped a tooth. With a little reading I found out the 4.9 doesn't use a chain, but gears, and they're most likely nylon.

Do the timing gears sound plausible for causing this? And if so, how much of a world of trouble am I in to change them?

Thanks guys...

 

Do you have the right mark? It's not the deep groove as you would think, it's smaller.

 

its also NOT the timing marks on the timing cover....it the tab on the left on the actual balancer...long saw toothed looking thing usually covered in road grime and grease

 

It's been a while since I've had time to go back out to the garage. I took some pictures this time though. The first attached picture is of what I'm using to set timing. That notch on the balancer is the only marking on it. After I cleaned off the cover, the tic marks read 0, 6, 10, and 14 degrees.

dr_bowtie: The only thing I see on the left side of the balancer (passenger side if you're looking at it from the front) is what is pictured in the second image. It's a peephole of some sort that the notch on the balancer passes right under. It's buried under A/C houses and other things so I had no direct line of site to it. Is this what I'm supposed to be using?

Thanks guys...

 

That's the one. I believe the deep notch is 10 degrees. Here's a better pic:

 

the one Sean listed is what I have as do many others....I am not sure what years used the cast in tabs on the timing cover?

 

Sean, Dr Bowtie, it was exactly as you guys called it. I eventually found the mark on the balancer that Sean said to look for, and used it with the timing peephole on the left side that Dr Bowtie said to use. I got the timing set tonight and it seems to of cured the miss for the most part. Thanks for all the help guys...