Hey guys.

I just got a 76 F150 3 spd inline 6 from my father in law. It's in pretty good shape, but isn't driving well.

It backfired on me twice with flames shooting out the tailpipe. doesn't get up and go if I get on the accelerator, and doesn't want to climb past 50. It was suggested that the timing might be off, and my father in law confirmed that he thought it was as well.

Here is my dilemma. I have never adjusted the timing on any car. I have the timing light, but am not sure what I actually do to adjust the timing. What do I actually "do"? I am not a "real" mechanic :-) so dumb talk to me if preferred! I have done lots of work on vehicles, but mostly just simple things like changing alternators, starters, etc.

Any help would be very much appreciated, and video and pictures would be tremendous!

 

You connect the lead to the #1 spark plug wire, and I guess there's probably a ground lead? Google or youtube will have better info. But once you get the light flashing with the #1's ignition cycles, you aim it at the harmonic balancer and observe the timing marks. You would loosen the dizzy hold down, and then rotate the dizzy to try to dial in on the appropriate timing mark.
Before doing that, get a fine-tipped paint marker or something like that, and paint the 0º mark, and the mark you're shooting for. They can be hard to see. The one time I tried using a timing light, I think that is what convinced me to put it away and go back to my own method of advancing until it pings, (or causes the starter to labor on hot-starts) and then backing off a bit. That was in the crowded engine bay of a Fox 5.0 Mustang, with untouched timing marks.

Also you can paint the whole balancer, or just around the timing marks, and then sand the raised area, leaving the paint in the scribed markings.

The carb could be suspect too. If you still have the original, do not throw it away or return it for core. Rebuild it or at least save it for someone who will. The carbs you get from the McParts stores are poorly rebuilt in sweatshops with inferior quality parts, and worse yet, with mismatched parts.

And welcome to FTE! Any pics of your rig?

 

Before you do timing remove the #1 plug closest to the radiator. Turn the engine until the piston is on the compression stroke at #1, which you determine by putting a small bit of wadded up kleenex in the plug hole - if on an exhaust stroke it should not blow out, on a compression stroke all the pressure should blow the kleenex out ot the plug hole. Get the piston to its highest point in the cylinder (use a thin rod or dowel into the cylinder to touch the top of the piston - when it is has risen to its highest point, now check the timing mark on the other side of the engine - should say it is at 0, aka Top Dead Center (TDC). Do that BEFORE timing it, as on these old engines it is common for that point to have slipped and you can time till the cows come home and never get it right. Make sure where your engine says is TDC actually IS. (This takes longer to describe than to do.)

 

I will go out in about an hour when there is more sunlight and check. What do I do if it isn't TDC? Also, it says on the engine block that it should be 10 degrees TDC. Do I go 10 degrees past 0?

 

Thanks for the input. I will try this morning! There will be pics to come. Lots of work that can be done over my next lifetime :-)

 

working on it now....

 

 

Joseph, if it has slipped you probably have a repair in front of you - there's no way to know if when the ring has slipped that it would stay consistently in one spot. It might, or it might not. I would also suggest you do some searches in the forums for "timing with a vacuum gauge" and see whether you feel confident enough to try that. You do not need to use the timing marks for that.

Tedster has a good point. Remove and plug the vacuum hose to the distributor. Put on the timing light, and as you rev the engine keep looking at the timing mark and make sure it advances as you rev the motor (slow rev is better than a sharp gun.) You should see the timing mark moving off the scale. If not, you may have problems with your mechanical advance in the distributor. That worked OK? Now take the vacuum line to the distributor off the vacuum tree, plug the port on the tree, then with the timing light aimed at the marks suck on the vacuum line. Again, your timing mark should appear to move. If this works correctly for both vacuum and mechanical advances, move on to timing.

 

there are two markings on this, and it's confusing me. i am attaching photos. these are on either side of the crankshaft. The first photo the marking are hard to see in the photo, but it is left of the pulley about a 1/2 of the way down in the photo

left side looking in from front

right side looking in from front

 

1 of the notches will line up with the timing scale in the 2nd picture.
I would pull #1 plug and turn the motor over by hand and using something feel for the piston to come up as high as it can and look to see what notch lines up with 0 / TDC on the scale.
Mark that notch and that is what you will use to time the motor with the light.
Dave - - - -

 

I have been told to ignore the marks on the driver side and use the ones on the passenger side only.

 

jackie - same here, to be honest I did not even know the driver's side marks were even there. Should be easy enough to verify (you would think if one side is correct the other would be as well) and it would definitely be easier to check your timing mark from the same side as the distributor. Especially if you are not blessed with very long arms!

 

Update. I was hoping, as you mentioned HoustonDave, that if you got one correct they both would be. That wasn't the case for me...at least not yet. I will have to get back to you on that one. after getting the passenger side timed, the truck still ran poorly. so poorly, in fact, that we had another combustion build up and blew open my muffler. That is now my current project :-)

 

In the first picture, it looks like the harmonic balancer pulley might be messed up. Check to make sure it hasn't spun.

 

Sorry I was on my phone in my earlier post and did not see in the first picture the scale also.

Now as I did post find TDC for the #1 piston and see what notches line up with what scale and you will then know what one to go by.
It will also prove if the balancer has turned or not because with the piston at TDC the notch / scale has to line up to one or the other unless it has turned.

When you were checking the timing you pulled the vacuum line and plugged it right?
What was the idle speed set to? If it was too high that would throw off the timing.

In 76 that motor should have electronic IGN and if so try and pick up another IGN box as I have see it posted in the 80-86 area they can do some strange things besides just stop working till cooled then work again only to keep happening till it craps out all the way.
If that does not fix it keep it as a spare behind the seat.

As for fixing the muffler because of the back firing. I would fix the back fire before the muffler or you could blow apart the new muffler.

When was the last full tune up done? Cap / rotor, plug wires & plugs? What is the compression on the motor like?
I had a car with newish plugs, looked new and not much run time on them other than moving the car around the house. It idled fine but as soon as the RPM was raised it would back fire out the exh.
Because the car did not run much I thought a stuck valve but a compression test said other wise. Changed the newish plugs and all was good again.

So you have a few things to check / do to fix the back fire / lack of power and timing I cant see to be the cause of back fire.
Dave ----