(I actually overheard a young mechanic ask his boss that!)

Here's the background:

1970 F-250 360CID C6, had the engine and trans rebuilt about two years ago.

Recently, was driving on the freeway when I felt some hesitation, similar to when one of the gas tanks runs dry (I don't think it was fuel starvation, since I'd filled both tanks the day before). I proceeded to move over to the slow lane, in anticipation of parking it on the shoulder for a while, but then the problem cleared and I was able to continue driving it, throttle response and everything. Drove it a couple more miles until I got to the exit I wanted and it didn't give me any trouble. Went about a half mile, had to stop for a left turn light at an intersection and it died.

Tried to restart it, but the engine turned over very slowly. Switched tanks in the hopes that it was fuel starvation, but that didn't change anything. Then it blew flame up through the carburator. That's when I decided to have it towed home, where I have the tools to work on it.

Points are a chronic problem for this vintage of rig, and it had been a while, so I decided to throw a tune-up into it. Plugs, points, condenser, rotor and distributor cap.

Comparing the distributor cap wires to the illustration in my manual, it looks like the distributor was installed 180 out during the rebuild. That shouldn't be a problem, so long as both the distributor and wires are installed 180 out. It still gives the same firing order. Besides, it's been running for the past couple of years.

With the new parts in, it sounds better, but it still doesn't fire. It's almost there. I've put the distributor in different places, but I can't get it to work. Using the timing light while it tries to start shows no timing mark anywhere. I've tried to turn up the throttle at the carb so that it would stay running long enough to set the timing, but it doesn't want to run for more than two or three seconds. All of this was with a cold start (valve closed in the carb).

I'm beginning to think that maybe it slipped a tooth on the timing gear.

So I'm faced with a couple of problems. One of them is "Where is #1 on the distributor cap?" (because I want to know if the dizzy is 180 out) and how do I find TDC?

Hypothetically, I could remove the valve cover and watch for the #1 cylinder's valve action; it should coincide with the piston traveling to the top of the cylinder when the exhaust valve closes.

The problem is that this engine has the air conditioning radiator in the way, and I don't have the same kind of access to the main crankshaft bolt like on the other truck. I may have to go buy another deep socket and have a machinist cut it down to the correct length. I'm not sure how to apply enough controlled torque to rotate the crankshaft otherwise. I'll pull all the plugs again and remover the fan belts to see if I can move it by hand.

Assuming that I can ID TCD on #1, the other question is "Which way should the rotor point?" Does it point towards the screw notch on the base of the dictributor cap, or does it point away from that? I know it really shouldn't matter, as long as the firing order is maintained.

Anyone have any observations about this?

Anyone have a diagnostic process to determine if the timing has jumped a tooth?

 

When you put gas in your rig was there a tanker there filling their tanks? If so it might have swirled all the crap in the bottom of their tank and the pump sent it right in to your tank. Check to see if your fuel filter is plugged. If so you prolly got crap in your carb also. Put the belts back on. With the plugs out (no compression) you can spin the engine by hand via one of the belts. Stick something like a wooden dowel in #1 plug hole to reach the top of the piston. The dowel should be farthest up when timing mark on TDC. Plus and Minus a few degrees because of the throw of the crank's wrist pin.

 

No tank truck to be seen, but changing the fuel filter's a good call anyhow (wish I'd thought of it when I was buying the tune-up parts). Maybe I can steal one off the other truck temporarily, as a diagnostic step.

Roger on the plugs. Number 1 in the top of the cylinder gives a 50% chance that it's TDC, so need to confirm by watching the closing of the exhaust valve.

Got any diagnostic for a slipped timing chain? I guess I have to go through with finding TDC on #1, then making sure the wires use the right firing sequence and if it can't set the timing, I'll have to dig into the front of the engine.

 

If I had a young "mechanic" ask that I'd sure as hell tell him where to stick his scanner.

 

Just pull #1 plug (pass side front) bump engine over with your finger in plug hole until you feel compression. Then continue to bump engine over or using ratchet on crank bolt until you see approx 12 deg BTDC.

I use a starter button but a screw driver can be used to jump starter relay.
I normally pull small wire off relay (closest to + terminal from battery)

Correct spot for number 1 is approx 1 o-clock looking from front.

Then make sure rotor is pointing to #1 on cap.

Loosen dist so it turns pretty easy.

Turn key to on and with coil wire pulled from dist and hold to ground while turning dist back and forth. When it arcs your timing will be set where you have it on balancer. I like 12deg for starting out.

 

I 'm not trying to be mean here!
But, I can add only 1 thing! You need to buy a motor manual for your truck.

See you'd be lost with out a computer to logging on here to post questions .

All this timing stuff is ez and in these motor manuals.
It's not like you just bought the truck. Right.

Hand tools are not much good if you don't know how to use them.
orich

 

Yeah.... I just smiled... hope he was embarrased, some folks learn really well that way

 

Don't have the clearance to put a ratchet&socket on it because the air conditioning radiator is in the way. I have the two "Army sized" sockets (too big and too small).

Ok, that's where the rebuilder put it, so I can live with that.

I'm pretty sure it's there, but I'll double check.

That all makes sense, but I've never tried it that way before -- thanks for the tip.

 

Yeah, yeah... need I point out that this is the twin to the truck I''ve been maintaining since 1976? That was before I had my first computer. Think I've worn out three timing lights and a couple of dwell meters on that other one. Also replaced the manual about 1985, since parts of it were too greasy to read and the spine was broken in several places. It got to the point where I could just about set the distributor points by eye.

At various times, on the other truck, I've had the heads off, the intake manifold off, replaced the starter motor, the alternator, the P/S pump, removed and replaced the radiator, the water pump and a host of other things. I've also jury-rigged an emergency throtle linkage repair with a piece of baling wire that I found beside the highway (My wife said "I thought that was just a cliche!").

You're right, the timing is relatively easy, and it's been a part of many of the other things I've had to do to that truck.

But I haven't done a tune up in a couple of years, and when you don't use it, ya lose it. So I'm not as familiar with setting the timing as I once was.

I couldn't find the firing order in the manual, but I remembered that it was shown on the intake manifold. Wasn't easy to read, but I finally got it. The wires checked correct against that firing order, assuming that the rotor was pointing in the right direction to begin with. I got out the small bottle of Testors modeling paint and painted a small white "1" on the #1 spark plug wire. I should use the same paint to highlight the timing marks on the balancer. I know it was a big help on the other truck.

I still think I'm facing something different. I'm pretty sure I put it in the ballpark, but it wouldn't keep running. The timing mark doesn't seem to be anywhere near the timing index (as in "not visible at all"). I get the feeling I'm about to dig into the front end of the engine to R&R the timing chain. Guess that means I should replace the water pump at the same time.

What bothers me is that the engine started to fail, then corrected again, then failed. If the timing chain slipped, I don't see how it could get back into correct timing. I would think that that sort of a failure would be a "Once it fails, it fails HARD" -type scenario.

 

put a breaker bar on the crank, and move it back and forth while watching the rotor, if it jumped timing there will be quite a bit of slack before the rotor moves.

 

That's an excellent suggestion.

I can visualize that happening if the chain tensioner foot came apart and disappeared. Wait, maybe that was the GM V6 engine I rebuilt. Still, too much slop there would indicate a fundamental problem for the timing.

I may have to remove the air conditioning radiator first, IOT get the clearance I need to get the socket onto the crank's end bolt.

Checking that is still preferable to opening up the front of the engine for a visual inspection if I don't need to.

Thank you.

 

I'd just pull #1 plug place your thumb over plug threaded hole & crank until it blows it off. This can be done while you have your timing light hook up while using a remote starter push button switch clipped onto the solenoid.

This way you not need to remove anything just to check. And you'll find#1 then check where dizzy rotor is pointing to.
This was listed by Boss9F100 earlier:

At one time the dizzy caps had a #1 molded into the top side next to #1 for location ID plug socket.

I'm guessing to checked that point are getting juicy to them. As while the plugs & coil & all the stuff first before digging into the engine..
orich

 

Also just check for rust in the gas. It can choke the sending unit and the tiny passages in the carb. Check the sediment can on the pump, don't just change the filter.
Jumped time on a rebuilt seems a bit much unless used parts went back in.

 

Heh... I just got a strange mental image of Will E. Coyote under the hood of my truck with the akward expression on his face that means "Ok, now how do I get my thumb back out of this engine?".

Ok, that would at least save me from having to dismount the air conditioning radiator. Thanks for that. I suspect I'll have to do it anyway, but if not, then so much the better.

You're right, I should check for spark at the spark plugs, but since it's almost running (runs for a couple of seconds), I'm pretty confident that the juice is getting there.

Anyhow, I'm gonna go play in my playground for a while and see if I can't skin a knuckle or something.

 

I'd be pretty surprised if there was rust. Part of the 'restoration' on this rig was to have both gas tanks dropped & boiled out. One survived (and was relined), the other didn't (and was replaced). That was done about the same time as the engine & tranny were rebuilt, call it two years ago.

Checking the bottom of the fuel filter can is habitual for me, any time I have the can off of the fuel pump.

The engine shop wouldn't need to gouge me that way. If they wanted more money from me on this project, they'd bill me for more man-hours ('cuse that's something I couldn't check). I'm sure I was billed for new parts, and confident that new parts were installed.

I have to agree that it seems premature for the timing sprockets or chain to fail. That's one of the reasons I'm reluctant to open up the front of the engine.

Those are valid cosiderations, though... thanks for chipping in.