I've been casually restoring my 1983 4.9 F150 for a while now. Some time back I tried to set the timing with an inductive timing light, but the timing mark on the crank pulley was nowhere to be found. I put the timing light on all six plug wires and it still didn't show up.
I know the timing can't be too far off, as the engines runs fine and doesn't really hesitate anywhere.
I am trying to do the timing now because I haven't set the timing before, and in addition to that I get stumbles or misfires at idle that don't stop it from running but that shake the truck a little bit.
Anyone got an idea whether I'm being dumb or if there is actually a reason for my timing mark to be missing? Pretty sure the engine is original.

 

After some time, the timing marks on the balancer can get dirty, filled up with crud and the like.

A sure fire way to find "0" on the balancer is to pull #1 plug....have a piston stop on hand (or a wood dowel or such)....or not....crank the engine 'till #1 cylinder is at or just before TDC on the COMRESSION stroke....screw in the piston stop, or plug in the dowel and turn the engine by hand CW 'till it's at TDC.
Make a mark on the balancer. Rotate the engine CCW (almost 360*) until the piston hits the stop or the dowel shows you're at TDC. Make another mark.

The distance between the two marks is TDC....that's your "0". You might be able to see some marks on the balancer now...if it hasn't slipped.

OR, you could pull #1 plug....rotate the engine CW until you have TDC close on the compression stroke - a finger over the plug hole...or a shop rag tucked into the hole...will blow out when you reach TDC on the compression stroke.

There's timing tape available to buy either on line or a parts store should have it. Once TDC is established, you could just put some marks down or apply the timing tape.

Stumbles or misfire is a carb condition for the most part (if not fuel infected) - mixture settings....a plug could be fouled, plug wire or wires not snug to the plug......Does she stumble or misfire at a higher - say 2k RPM - in PARK or NEUTRAL?

 

There should be a groove in the balancer. I put white paint in mine for ease of visibility.

 

I don't think the misfire happens at all when it's off idle. It feels like it drives totally fine, but when you listen to the engine noise by the tailpipe when it's idling, you can hear the exhaust popping intermittently. I am going to vacuum tune the carburetor this weekend and check out timing together, hopefully that will clear it up. As for the mark, I think for now I'll try to further inspect and clean the crank pulley so that I might be able to see it easier. Then I can start checking it out further if need be.

Good idea, I'll try that. Will see the truck again tomorrow. Hopefully the mark will show up.

 

I have a nylon brush for my drill that I hit the balancer with. Then I hit the starter just enough to turn the engine a little bit and went all the way around. I line of white chalk on the correct timing mark and it was relatively simple to get it timed properly.

https://www.harborfreight.com/2-inch...ush-91367.html

 

Intermittent exhaust "popping" sounds (hehe) like a partially fouled plug or plugs. Pull 'em, clean 'em and adjust the carb.

Take it from there.

 

Well, another thought is mebbe a broke valve spring....but if it's only at idle and gone with increased RPM, hmmmm, mebbe just some fouled plugs.

However, a test for bad/broke valve springs:

Take a dollar bill, stretch it over the tailpipe and watch what it does.....if it wants to suck back in, you have a valve/ spring.valve problem. Not sucking back in? Check the plugs.

 

So a bad/broken valve spring only showing up at idle and not at higher RPM?
If the spring was that bad to show up at idle it would also show up at higher RPM.

On motors using carbs I have always heard popping when at idle.
Remember at idle the air flow is low and fuel can / will fall out of the air and cause idle issues and that could be popping.

I would go over everything to make sure it is all good and not worry about the popping sound.
Dave ----

 

Agreed. And that was the rest of the sentence.....That's why I said check for fouled plugs......the dollar bill (or 5 dollar bill) test was just for piece of mind....

 

Messed with the truck a little bit today. I checked out the timing mark again with a timing light connected and once again there is simply nothing showing up on the balancer. However I spotted a notch cut into the disc when I looked at it from the bottom with the engine off. For now, I'm running it as it is because the timing can't be too far off (it runs well at all speeds).
I don't think the popping is a big deal. I listened a little better today and only heard it at idle. Sounds pretty normal overall. In addition I "fixed" my broken pedal bracket with a c-clamp for now, hopefully it will be less likely to break more until I can get a "new" one from a JY.

 

Check the rubber between the metal on the balancer. Does it look cracked or split?

Can you get pictures of the offending area on the balancer?

 

 

What they mean is the crankshaft balancer has an outer heavy steel inertia weight pressed or sandwich bonded with an elastomeric rubber compound between it and the inner cast basket. This allows the heavy weight to lead and lag a bit. Anyway when they get a few miles or years on them the rubber rots, the bond breaks and the inertia weight slips off index or clock making the timing marks useless. It won't absorb any vibrations too well either but that's a different issue.

The OEM timing marks on the balancer are often VERY faint, sometimes a light emery paper through the paint will bring them out.

 

Something screwy going on here with the pictures.....None came up when I went to this thread but when I went to "Quote" in reply, one picture came up....can't make it out too well, either.

EDIT: ONE picture came up when I went to "edit" .....hit 'SAVE' and no picture shows in the original thread.....WTF???

 

This is not the only post I have seen this on.
I even close my browser and reopen and still same thing.
The 1 picture I tried to look at looked to be hosted on here so wonder if that is where the issue is?
Dave ----