98 f150 4.6

I am changing the cams, valve springs, and timing chain in my truck. I have pulled the valve cover on one side and the cam out and have come across a delima. I think I know what to do but I would like to know if I am overlooking something.

The valve spring compressor tool I have functions with the cams off. It is designed so that you do not have to hold the spring compressed with one hand and work with the other. I have two TDC tools. Neither of them thread into the head. I do have a dial indicator and am thinking I can use that to find TDC in each cylinder or I can tap out one of the old spark plugs and make my own TDC tool. The spark plugs thread in and out no problem.

My bigger Delima is that I also have two air valve holder tools. Neither of these will thread into the head either. One of them, the head of the bolt wont fit into the spark plug hole and the other simply wont thread in.

What I am thinking is that I lock the timing chain on the cam sprocket (zip ties) and I also marked it with paint. do this for both sides. also mark the bottom sprocket and if possible zip tie the chains in place there. Then take the chains and sprockets off.

I can then turn the motor to TDC on each individual cylinder and change the valve seals and springs.

1st question I have is does the cylinder come up high enough that all I need it for it to be TDC? or do I need to stufff some nylon rope in the cylinder?
2nd question, is it ok turn the crank without the timing chains connected and will it be right back where I started when I put cylinder one at TDC?
3rd question. Is the TDC mark on the block TDC on the intake stroke or the exhaust stroke, or it the mark TDC for both strokes, and does it even matter given the fact that no cams are in the truck at that point?

any help greatly appreciated.

if anyone is going to ask why I am doing this, the build thread in my signature goes into detail as why I am doing irrational work and spending irrational money on an old truck.

 

Locating Tdc doesnt need special tools, a 1/4" wooden dowel will work.... Even a plastic straw from McDonald's

Using air to hold the valves will make the engine want to spin over from tdc.... If too much is used. You got to limit it to low pressure.... I suspect it would spin more freely without the timing chain on.... For sure only one spark plug at a time should be removed. I've had to fight with a breaker bar to hold an engine at TDC doing leak down tests before with only 25 psi.. multiplied by the area of the piston that's hundreds of pounds of force pushing down on the piston.....

Ive used air to hold valves before but I don't remember how much... It was a push rod engine so it was a lot easier too than overhead cam.. But you will need a regulator that does fairly low pressure.

I think the rope trick is prudent.

 

Thanks. I was overthinking the TDC aspect for sure. Its also good to know that about the air. The videos I saw online they were using 90 lbs, so hearing you have had issues with even 25lbs gives me something to think about for sure. If I do the air route, I will have to make a tool out of a spark plug as the ones I have don't work.

After sleeping on it, I think my biggest concern is, if I take all of the sprockets and timing chains off the truck locked in the same orientation, then turn the motor, then put it back at tdc and put the timing components back on, will I be back at square one? or will my timing risk being 180 off or any other amount off?

 

update. I realized while driving to the HF to pick up another tool I didn't know I was using. I am way over thinking this piston position. the pistons only have up and down, the different strokes are all accounted for in the head and not in the block.

It did end up skipping time on the lower sprocket but I have a brand new timing kit with a chain with marks. I have to time the new cams anyway so Ill just start at zero and then degree them from there.

 

I only did this job once years ago on a chevy 350 and I fed a rope in the cylinder through the spark plug hole and brought the piston up against the rope and it held those valves up as solid as a rock.

 

I did the first one hooked up to the compressor. It worked at holding the valve up. I was running 50 lbs and it looked like the engine was staying put. Right about the time I got the last keeper on the sound of the leak changed. The engine had rotated (cylinder 5 had the plug pulled also). The compressor was still keeping up but I don't know for how long and that was the easiest of all of them to get to.

After that I decided I would just use rope and that has been working fine. I put in about 4 hours today and got six of them done. I am not the fastest at it for sure and the 6th one probably took an hour alone. The next one should be pretty easy. I am going to have to do number 8 with a scope set up and use the screen. Its completely hidden.

 

I just use shop air
120 lbs or even 160 works fine
I have also dropped a valve doing a 460 years ago
They will come right the hell back up, when you turn the crank and force the piston and valve up at the same time
The old rope trick is for a 52 Packard but works on them all

 

I know on the passenger side that the first valve closest to the front is the intake valve. On the driver side are the intake valves also the front one on the cylinder? I am having trouble finding this information online.

 

You just look at the port connected to the valve
The valve arrangement used to be in books, but it is easy to tell if you follow the internal port in the head

 

Thanks, I was watching a video last night and noticed that you could see the porting on the head. I had not noticed that before. I did not remove my intake manifold and am trying to avoid doing so. The number 4 cylinder exhaust valve is on tonights to do list and will most likely decide if the intake manifold comes off or not. I am going to try and do it using my bore scope to see but TBD how that will play out.