Engine Rebuild revisited...

[SanDiegoXJ]

OK, so I have a thread in OEM:
http://www.naxja.org/forum/showpost.php?p=245940965&postcount=28

Does that look like the correct position for a timing chain at TDC on the compression stroke? I'm only asking in SoCal because I figured some of you might actually be able to swing by and take a look if need be.

But before I popped off the balancer, I checked, and rechecked I was at TDC on the compression stroke by removing the #1 plug, shoving my finger in it, and turning the engine until I could feel air press, at which point, I then continued to turn until the mark on the HB reached 0 degrees.

It just doesn't seem like it would run if the timing was that far off.

 

[WraithKWK]

http://www.youtube.com/watch?v=0HhcJ4UfYDg

 

[SanDiegoXJ]

Yeah, that's how the FSM shows it. And it seems to me that the TDC they are looking for is at the completion of the compression stroke, but it seems that mine is set to precede the compression stroke

I guess my real question is, am I getting the correct TDC? Should it be at TDC after it blows air out the spark plug hole (as it is now)? or should I spin it the crank another 360 degrees to be at the beginning of the compression stroke? If I spin it another 360 degrees, it lines up.

Oh, another thing, does my timing chain look loose? appears to have more sag than in that video.

 

[WraithKWK]

Mike shoot me a message with your number I don't have it anymore.

 

[GSequoia]

TDC is compression stroke.

 

[WraithKWK]

If the Cam is mis-aligned with the crank the Valves will be in the wrong position. Making TDC feel a bit off

So yes your TDC, is incorrect.

 

[markw]

The dots should align with one another. So right now #1 should be on the exhaust stroke.
If both valves are closed on #1, then there's an issue. It could be as simple as the mark is in the wrong position on the gear. We can cycle the engine through by hand and watch the valve train. I think I still have my degree wheel around here somewhere. Did you swap the cam, or are you just replacing the timing set?

I can shoot by and take a look if you need. I'll pm you my #.

Mark

 

[SanDiegoXJ]

Sent you a PM mark.

But yeah, that's the top of the compression stroke, and it looks like the valves are closed to me. But I've got the valve cover off and the oil pan off right now...so if you've got some time, I'd love to have another opinion. I'll even feed ya beer and steak. =)

 

[SanDiegoXJ]

If the Cam is mis-aligned with the crank the Valves will be in the wrong position. Making TDC feel a bit off

So yes your TDC, is incorrect.

That was my thought at first, but then I thought more...probably dangerous, but too late now.

The FSM said the valves should be relaxed at the top of the stroke, they are.

The TDC on the compression stroke should be after the compression...which is where it is when the #1 cylinder is at TDC and the distributor is pointing at position #1.

If I move the dot 180*, hypothetically, the pin count between marks will still be 15 as stated by the FSM.

Now, the issue that followed after I posted this, and it's updated in the OEM thread, is that 2 spark plug wires had funky resisitance. On first test and second test, I could get no reading from the Ohm meter at all. by the third test, I found I could rotate one of the electrodes around the spark plug connector and watch the resistance bounce around between 0 and no reading meaning it had hot spots on it. That, in itself may have been the problem...all the effort may have been for naught, but at least I got to verify that whoever built it (I think it was Cal) did a swell job building the engine. =)

Here's the whole thread...http://www.naxja.org/forum/showthread.php?t=1097908

 

[WraithKWK]

That's crazy, If I remember right you went with a stroker. So the Crank would be different. The Alignment dot could be in a different place than the stock crank. So setting cam timing could be difficult.

So you think you have 2 bad wires.

 

[SanDiegoXJ]

Dunno, but new wires should be here tomorrow, and I can rule that out when I get it all back together. Only other thing I can think is the wiring harness. After the engine fire a while back, a new harness went in and several connectors had to be crimped on. The Jeep ran fine then, but if one of those connectors got pulled, that may be it too.

 

[SanDiegoXJ]

And no, no stroker.

But yes, Mark, they did put a new cam in it.

 

[SanDiegoXJ]

One more question...I'm assuming the cam gear can only go on one way.

Is it possible the cam gear got installed backwards? And if so, are these gears set offset any balance?

 

[SanDiegoXJ]

Just found http://forums.off-road.com/jeep-short-wheelbase/168148-258-6cyl-timing-marks-alignment-2.html

Guess this isn't as uncommon as I feared.

 

[markw]

The other question is since it's a new cam, did it get broken in properly? On new cams you should run it around 3k or so for the first 15 minutes after starting it.

 

[SanDiegoXJ]

Mike had me hold it above 2k for a while, I would guess about 10 to 15 min