Hey there! Been crusing in my 72 f-100.....had a lot of work done on it the last 6 months cause its been sitting for over 5 years. The entire fuel system and ignition system is new...(except the timing chain..still the original one). It was running great except that it was having trouble starting. I had used it for work, and almost didnt get it started when I needed to go back to the plant. It finally started, and when I got back to the plant I shut it off and restarted it a few times. It worked for 2 times and then just cranked. It was cranking real slow, so I thought the starter was drawing too much off the battery. I replaced the starter....it cranked a lot quicker but never turned over. Over the last few weeks, ive replaced the points, condenser, and plugs. Still nothing. Ive moved the dist a little to try to adjust the timing, but nothing helps. Would I be right to think the chain has jumped or broke? I know I can bring the #1 piston to the top and see if the rotor is pointing to the right plug wire.....is there a way to reset the timing, or am I better off having the chain replaced? The truck has 146K on it, and I dont think its ever been replaced? Thanks!

 

If the truck is producing spark, and it is getting fuel, I would strongly recommend you check your camshaft timing.
Based on your description, I wouldn't try to start it again until you have checked it. The gears and the chain wear and stretch over use. The gears installed by the factory, if aluminum with plastic teeth, were soft, designed to eliminate noises. The teeth often fell off, and the aluminum wore down, retarding the camshaft timing.

The chain accumulates all this wear. The following is an easy check to determine the amount of slack, slop or wear, in your timing chain.

It is not necessary to remove any components as long as you can see the timing marks clearly. It can be done with one person, but a second person can be helpful if the distributor cannot be easily seen while turning the crankshaft from the front of the engine. This test cannot tell if a chain has jumped; it can, however, tell you if there is enough slop in the chain to have let it jumped.

Tools: Breaker Bar with socket to fit the front crankshaft bolt

1. Mark the TDC or 0 mark on the damper clearly. Ensure the rest of the timing marks can be clearly seen; clean them if necessary. You may find it useful to scrape a little chalk over them to highlight them.
2. Remove the distributor cap and place it out of the way. You must be able to see the rotor while turning the engine with the breaker bar. It usually is not necessary to remove the spark plugs, but some high compression engines may require it to get an accurate reading.
3. Turn the engine in its normal rotational direction until the TDC or 0 mark is lined up with the pointer.
4. IMPORTANT: Do NOT turn the crank backwards just to line it up. Doing so will give erroneous results. You MUST rotate the crank in ONE direction only. If you overshoot, just go around again. This is where it may be helpful to remove the plugs.
5. Once the TDC and 0 marks are lined up and while watching the rotor, rotate the crank in the opposite direction. When the rotor begins to turn, STOP. It may help to have a helper push against the rotor's direction of rotation. (Remember, it will be going backwards at this point.) They can feel it begin to move more accurately than you can see it begin to move.
6. Note the value of the timing mark the pointer is indicating. It will be BTC, because you went in reverse of normal rotation.
7. This value is the amount of slop your timing chain has in degrees of rotation. Anything less than 10 is safe, but performance begins to fall off after 5.

 

Banjopicker is spot on, if you have an engine with a timing chain, he's your man.

But I'd ask: Because some engines do not use timing chains, just what engine are we discussing here?

Those that do not use timing chains have a Crankshaft timing gear to Cam gear set up instead.
Thus the jumped timing chain hypothesis would be flawed.

I've not seen gear to gear set up break yet, might get worn, noisy & loose & out of time some tho'.

FBp

 

Thanks for the great info! Im gonna have the chain/gear replaced. I should have done it a few months ago when I replaced the water pump, but didnt think of it. She has a 360 in it....cant wait to get it back on the road. She was sitting for over 6 years when I was living up north, and I really miss driving her. My next projects will be the rear end seal and the oil pump/rear main. One of my employees used to have a 72, and about has me convinced to do the oil pump myself. Hopefully after that there will be no more leaks! She was running pretty good considering how long she sat....was even managing 12mpg...LOL..wonder if she will run better after the new chain/gear? Less slack on the chain=more constant timing?

 

i didnt bother doing any tests, i just removed all my pulleys, yanked the harmonic balancer, took off the timing cover and looked at it. took an afternoon of my time and about 4 beers. its easy.