Distributor timing on 258, have I jumped time?pic> - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 10-18-2002, 03:25 PM
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Distributor timing on 258, have I jumped time?pic>



So, my Jeep bucked and quit running on me at a stop sign a few weeks ago. Been messing with it since, but it has not run. Please do a search of my previous posts for more info. I have rebuilt the carb, but she refuses to run.

I have tried blocking fuel line to carb, pulled all plugs, cranked engine with throttle held wide open to dry motor out, cleaned plugs well. Reinstalled cleaned plugs, left fuel line to carb blocked off. Sprayed ether down carb, will not run.

Pulled coil and mounting brackets, cleaned all contacting surfaces including mounting bolts, brackets, etc with degreaser and wire brush and/or sandpaper. Cleaned contacts on coil with sandpaper. Checked coil primary and secondary resistance. Cleaned batter terminals, both insides of cables and posts. Removed ground cable from block, cleaned bolt, connector, washer and block mating surface.

I get good spark at the plugs.

I can spray ether down the carbs and it will not run. Not even cough.

I am suspicious that I may have jumped time.

I turned the engine over using the crank bolt to TDC on the compression stroke for #1 cylinder. Marked all high tension leads from distributor, pulled distributor. Less than 10K miles old plugs, wires, cap, rotor.

I have a Haynes manual, and from the looks of it's diagram, I have jumped time. Notice that #1 cylinder in the Haynes should be closest to the distributor mounting screw. Then look at the picture of my rotor and cap. You can clearly see that my #1 is 2 terminals from the distributor screw.





BUT, this is the way it has always been? I mean, the wires did not jump from one terminal to the other. And it ran for 8 years like this.

Any ideas?

Anyone?

I *REALLY* need some ideas on why this thing just quit, gets spark, gets fuel, seems to have compression, but just will not run.

Thanks,

Mike
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post #2 of (permalink) Old 10-18-2002, 03:38 PM
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Re: Distributor timing on 258, have I jumped time?pic>

It really doesn't matter which tower you call #1,
as long as the rotor points to it when it's time
to fire #1.

As long as you haven't taken the distributor out,
or remember what the position it was before you
messed with it, you can make an approximation.

Rotate it until the mark says TDC. Check to make
sure it's really TDC with a probe througfh the
plug hole. Adjust till the piston is at TDC.
The mark should agree. If not, your damper has
slipped.

Now note the rotor position - it should be just
slightly ahead of the number # terminal. If you
had it set to 8 degrees advance, it should be 8
degrees off.

If not, it could have slipped.



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post #3 of (permalink) Old 10-18-2002, 03:47 PM
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Re: Distributor timing on 258, have I jumped time?pic>

Thanks for the response.

I have not moved the distributor at all, and it is still locked down tight, at least thre is no movement at all when I try to twisw the body of it with all my strength in my hand.

I did use a dowel in the plug hole to get it to TDC(maybe off by a few degrees, max, I used a breaker bar and rocked it back and forth until I was happy that it was as close to TDC as I could get it without a dial gauge.

I will go check the damper timing marks. Back in a min.

Mike
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post #4 of (permalink) Old 10-18-2002, 04:01 PM
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Re: Distributor timing on 258, have I jumped time?pic>

Timing on the damper *appears* to be btwn 16 and 18 degrees.

Again, this is done with a dowel in the plug hole, but I did just go rotate the crank and resettle the piston to TDC. It was closer to 16 when I wnet back out, and after moving the crank several degrees and comming back to TDC on #1 it looks closer to 18 degrees.

What could cause the disparity?

I do have 120,000+ miles on the motor. Would the timing chain jumping one tooth put the timing off about as much as mine seems to be?

What's my next step?

Will rotating the distributor until I have 8 degree timing on the damper fix things? I would assume it would not if I have jumped time?

Mike
post #5 of (permalink) Old 10-18-2002, 04:04 PM
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Re: Distributor timing on 258, have I jumped time?pic>

I had something like this one time. My spark looked fine out of the cylinder, but under compression it would not fire. Try a new coil. That fixed mine. Good luck!
post #6 of (permalink) Old 10-18-2002, 05:06 PM
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Re: Distributor timing on 258, have I jumped time?pic>

Looks like it jumped time.
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post #7 of (permalink) Old 10-18-2002, 05:25 PM
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Re: Distributor timing on 258, have I jumped time?pic>

Do you know if I can check the timing by just cranking the engine over?

I have the plugs out of it now and the throttle blocked WOT, so there is very little resistance to the engine rotating and it spins pretty quick.

If I ground all the plugs using jumpers, and use my inductive timing light on the #1 wire(with the plug ground of course) and have the GF crank the motor I should be able to read the timing, right?

How else to I assertain weather or not it has jumped time?

Pull the timing cover off? I already have the fan, fan clutch and radiator shroud removed.....

Mike
post #8 of (permalink) Old 10-19-2002, 12:43 PM
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Re: Distributor timing on 258, have I jumped time?pic>

Yes, most timing lights will work at cranking
speed as long as you have a good spark.

The TDC - remember, the TDC mark on the damper
can't change unless the damper slipped or the
crank broke - doubtful that's the problem.

When the piston is at the top the mark should say
0. It's hard to tell exactly, but if it's close,
assume the damper mark is accurate.

Set the mark right on 0, TDC.
Then look at your rotor to see that it's pointed
roughly to #1, offset by the initial base timing
amount.

Your distributor is driven through the timing chain,
so a jumped chain can change the timing.

Another way, but sometimes you can get fooled:
Take the cap off, move the crank by hand in one
direction until the dist rotor moves. Mark the
damper at that spot.
Then move the crank by hand again in the opposite
direction till the dist rotor moves again. Mark it.

The difference between the 2 marks should not be
more than about 4 degrees for a new chain, 8-10
degrees for an old one in need of repair.
More than 10 degrees means it may have jumped.
In that case, you'll have to dig down to see.

Sometimes they can jump but still remain under 10,
but rare.




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post #9 of (permalink) Old 10-19-2002, 03:49 PM
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Re: Distributor timing on 258, have I jumped time?pic>

OK, I just checked the timing like I said before with plugs out.....

Looks to be right at 0 degrees on the engine timing marks using my timing light.

I also marked the damper, turned motor and marked it again...

It is 10+ degrees of slack rotation before the rotor moves.

What does this tell me? That it should still be running, if barely?

thanks,

Mike
post #10 of (permalink) Old 10-19-2002, 06:20 PM
 
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Re: Distributor timing on 258, have I jumped time?pic>

I know this is going to sound like dumb advice, but I'm going to give it anyway. Check all of the fuses in your fuse panel. I had similar condtions once with my CJ and after replacing the coil, ignition module, tracing wires looking for a fusable link that was bad, etc...it turned out that there was a bad fuse in the fuse panel that kept it from starting. I don't know remember what fuse it was, it was something that I would have never suspected, but sure enough, replaced the bad fuse and she started right up.
Sounds like you are exhausting your resources, so it wouldn't hurt to check it.
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