Wont stayed timed

[Jwelch]

Is there some reason why my truck will not stay timed? I am tightening the bolt the holds the distributor in place but it still will not stayed timed. Also it seems to have little hesitations unless I am getting on it. Could this be a timing belt problem? Thanks.

[spartman]

Our engines do not have timing belts.

What speed are you trying to time your engine at?

You need to also plug off the vacuum advance when you are timing as well.

Could also be that your distributor bolt is not holding down your hold down tight enough.

[Jwelch]

Really, no timing belt, I did not know. I am timing it at idle and I do have the vacuum lines plugged. When I tighten down the hold down bolt I crank the Sh$t out of it. Is it supposed to have a lock washer or something because mine does not?

[Jwelch]

Sorry guess I should have started with the fact that it is a 1970 F-100 with a 360.

[spartman]

Yep

the v-8's have a timing chain set.

Could be the timing gears are worn as well.

Dont really need a lock washer but they never hurt

[BobbyFord]

Also if you've got some tire chalk or a scribe, at the base of the dist. where it goes into the intake make a line or scribe mark from the housing to the intake so that you can see if the dist. is slightly spinning out of time.

[spartman]

That is a good idea.

Wish I had thought of it.

[Jwelch]

Is there a way to check and see if it is the timing gears withOUT taking it apart? I will try putting a lockwasher on and also make a mark to see if it is slipping. Thanks.

[spartman]

bout the only way that I can think of is if you can hear the chain flopping when its running.

[BobbyFord]

Is there a way to check and see if it is the timing gears withOUT taking it apart? I will try putting a lockwasher on and also make a mark to see if it is slipping. Thanks.

To be safe you may want to disconnect the battery.
Pull the dist. cap off and slowly and carefully rotate the engine back and forth (by the fan or if you have a fan clutch, by a breaker bar on the crank) and see how long it takes the rotor to change direction in correspondance with the crank. It will have a small amount of lag, but a lot will be noticable and indicative of a worn timing set.
You may have to tighten the belts if you're using the fan method.

[FORDification]

A couple other possibilities:

1) The distributor's drive gear roll pin has sheared off, and just binding a bit....enough to keep it the gear from spinning on the shaft, but still loose enough to slip a tiny bit more every now and then.

2) The harmonic balancer. If the rubber connecting the inner and outer rings is failing, then the timing marks will keep moving on you, making it appears as if it's gone out of time. You can check this by using BobbyFord's suggestion...make a long straight line across the harmonic balancer and then run the engine for a while and see if things are still lined up afterwards.

Other than the hesitation, how does it run?

[sideoilerfe]

Is there a way to check and see if it is the timing gears withOUT taking it apart? I will try putting a lockwasher on and also make a mark to see if it is slipping. Thanks.

Remove the fuel pump and stick your finger in the hole. You can feel the gears and chain. You might have the original timing set on it and if so, the nylon teeth are probably worn off by now.

[BRUTUS_T_HOG]

im sure if the cam timing was slipping all the time it wouldn't even be running by now

[rubiranch]

How many degrees is the timing changing and do you check it at the same RPM every time??

The most accurate way to check timing chain backlash is to use a breaker bar and a 15/16 socket on the harmonic balancer bolt.

Remove the distributor cap and slowly rotate the crankshaft so that the rotor points towards #1 (on the dist cap) and align the timing mark at TDC at the timing pointer and the degrees marked on the harmonic balancer itself.

Then slowly rotate the engine the opposite direction closely watching the distributor rotor. When the rotor begins to move stop and note at what degree the timing pointer is at.

I would say that the chain is not "real" bad with up to 15 degrees backlash and maybe even a little more, 12 is probably normal.

A new stock replacement timing chain can have up to 8 degrees backlash after only a few thousand miles.

If there is zero backlash then the gears and chain are severely worn and the chain is most likely riding on top of the teeth of one of the two gears, most likely the cam gear.

Worn distributor breaker plates (the plates that the points are attached to) could be worn also. Rev the engine to about 2000 rpm and disconnect the vacuum advance and reconnect it and note the dwell change using a dwell/tachometer. I would say that 4-6 degree dwell change would be normal and the dwell should decrease (increasing point gap) with the vacuum hose connected vs the hose being disconnected.

An improperly lubed distributor cam and point rubbing block could be causing the dwell to change as the rubbing block wore down due to a lack of proper lubrication. For every 2 degrees the dwell changes the timing changes one degree. As the dwell degrees increase the timing retards.

Others have mentioned good probabilities like the role pin in the distributor drive gear breaking and the gear slowly rotating on the distributor shaft.

I have always like to clean the timing marks with a wire brush and them rub a yellow tire marker over them to fill the numbers and lines and then wipe the excess off with a dry clean rag. The yellow marker stays in the little groove and makes the timing marks easier to see. You need to remember that there are 10 degree marks on both sides of TDC, you want to set the timing on the side that is marked with 10, 20 and 30 degrees and have your RPM set to or below 600 RPM.

Let us know what you find.

[wildcard]

Man, you just can't get that kind of info anywhere. What a site.