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Unread 01-31-2008, 03:11 AM   #46
Alfons
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Good Morning!!! Here's a question and some suggestions to get your day started:
  • I know you had some troubles with the front end (timing cover etc.), what did you end up changing and what procedures did you use to set up the timing gears etc?
  • Do a fuel pressure check with and without the vacuum line attached to the regulator. With vacuum attached, you should get 31psi and without, you should get 40+. Plug the vacuum line when you take it off the regulator for the test.
  • Check the manifold vacuum, you should read around 17 in. Hg (inches of mercury) on an engine with no leaks and no problems.
  • Do a cylinder head pressure check to see how close all the cylinders are to the same pressure.

Here's a good write-up on vacuum testing.

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Unread 01-31-2008, 07:03 AM   #47
laybackman
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Another thought for you. Are you sure your fuel is fresh? Old gas will give you awful performance also, especially at idle.
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Unread 01-31-2008, 09:37 AM   #48
veritas4156
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Holy Crap I slept late today... Don't have class till 1:15 so I didnt set my alarm and ended up sleeping till 11:30.

I'll test everything you said to alfons after I reclean my throttle body and I change my plugs.

And I do believe its fresh gas(well 3 weeks old now) but I've put Seafoam and Isoheet in it so it should be as good as fresh gas now anyway(Seafoam is my liquid mechanic).
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Unread 01-31-2008, 02:37 PM   #49
veritas4156
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Alright so I didn't test all the other stuff that alfons listed yet, but I did try this. I had my friend start the car while i was holding the distributor in place, and i rotated it and had him use the timing light. By turning the distributor slightly away from the block we got it to fire at 2 degrees BTDC which sounds about right at idle.

Anyone know what its supposed to fire at?

My problem here is this. I can't set the distributor to the position it was in when it was firing good. The position is in between two splines on the distributor. If I'm thinking correctly this narrows it down to the base timing being off slightly. Am I correct in this thinking? Let me know, otherwise Superbowl Sunday I will be wrenching from the crack of dawn until the game starts and then starting again afterwards.

Would it be horrible if I fabbed up a temporary bracket to mount the distributor in that position until I actually have time to redo the base timing?
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Unread 01-31-2008, 04:34 PM   #50
Alfons
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Quote:
Originally Posted by veritas4156
My problem here is this. I can't set the distributor to the position it was in when it was firing good. The position is in between two splines on the distributor. If I'm thinking correctly this narrows it down to the base timing being off slightly. Am I correct in this thinking? Let me know, otherwise Superbowl Sunday I will be wrenching from the crack of dawn until the game starts and then starting again afterwards.
That's why I was asking how you assembled the front end - that's another place to adjust the timing, just not very easy to get to. If you can explain exactly how you aligned the gears and chain, it might be helpful in finding the problem.

Quote:
Originally Posted by veritas4156
Would it be horrible if I fabbed up a temporary bracket to mount the distributor in that position until I actually have time to redo the base timing?
This is what you use to clamp down your distributor, but if one of the "locking ears" covers the bolt hole, you might have a problem - I don't know anywhere else you can bolt it.



This is how it fits on the distributor:



I could send you one with the ears broken off if you're interested in paying the shipping - distributor would be free (no sensor included, you could put your's into it).

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Unread 01-31-2008, 07:20 PM   #51
veritas4156
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Hmm... I can probably get a distributor cheaper from the junkyard than from paying shipping to you(cross border bull would take way too long too) but thanks for the offer.

The way I set the timing was by taking the cover off(and the radiator and fan and all that stuff) and setting the crank to TDC by putting a pencil in through the spark plug hole to find the high point(or what I thought was TDC, when I put the pulley back on it was at 2 degrees BTDC according to the cover). The cam timing mark was about a centimeter lower than it should have been, so i rotated the cam to get it in position. I then replaced the gears and chain(the old chain was shot, lots of slack) so that the marks and centerpoints of the cam and crank were aligned(used a string to be sure). Then I put everything back together.
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Unread 02-02-2008, 10:41 PM   #52
veritas4156
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hey i just thought of something. Any chance the distributor mounting gasket would change the timing a little bit if i had one? because i dont....
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Unread 02-03-2008, 04:56 AM   #53
Alfons
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You should have a gasket to stop the oil, but it won't change the timing.
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Unread 02-03-2008, 10:23 AM   #54
veritas4156
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alright, i wasnt sure if that would throw it off because it changes tthe height. thanks im gonna go work on it till 545 and then time for FOOTBALL
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Unread 02-03-2008, 06:10 PM   #55
veritas4156
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where do you hook the fuel pressure tester up to? would that be where the fuel return line is? i tried disconnecting my vacuum line from the regulator and it didnt change the way it ran at all. i thought it should and i have good vacuum so i figure i may need a new regulator. lemme know what you think
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Unread 02-16-2008, 12:09 AM   #56
cjjcall57
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4.2 seating distributor same as 4.0

I knoww you are all talking about the 4.0 but Iam having a the same problem wit my friends 4.2. my haynes manual states seat the distributer so that the rotar is pointing at the 4 oclock position (31 spark plug post). is this correct for the 4.2? Another thing I noticed when I accuire TDC according to the manual if I alline tge damper wheel mark at 0 on the scale the piston is rotating down about 1/4 in. if I set the piston right TDC the damper wheel mark is about 15 deg before 0. The engine is a rebiult crated motor I checkd the timing it apeered to be correct. any advise on how to seat the disrtibuter. one more thing since I couldn't get the engine to start I hooked up the timing light to see if #1 sprak plug was firing at the correct time I notice #1 would not always fire at TDC, but fire between about 40 deg before or after. any idea as to why. I bought a new coil
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Unread 02-16-2008, 09:33 AM   #57
veritas4156
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Sounds like your one(or 2) tooth (teeth) off on the distributor. Does the 4.2 have vacuum lines hooked up to the distributor? if it does check to make sure you're getting good vacuum on these lines, if not the adjustment for the timing will be off. I really don't know much about the 4.2 just that its similar to mine but carbd so I would try these two things and if they don't help then I would wait till alfons responds to this post, he is quite knowledgable about the topic.
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Unread 02-01-2009, 10:46 AM   #58
1998JGC
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Good Afternoon to All!

I have read this Thread numberous times. I just rebuilt my engine on my 1998 Jeep Grand Cherokee. I have everything hooked up, but the engine will not stay running (hard turn over with some hesitation). I beleive the timing is an issue. I placed the dist in as discribed in the previous postings and there is no improvements.

Can anyone help me? I will post pictures if anyone needs to look at the engine.

Thanks in advance!
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Unread 02-08-2010, 06:07 PM   #59
yellowoctupus
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Timing chain / distributor timing off...

Hi, I just replaced my timing chain (91 4.0), and the truck seems to run fine now, but is a bear to start. Sometimes it will just fire immediately, but more often than not it acts like the timing is super advanced (I think), it will spin for a while then pop, which just stops the engine spinning over, it's been taking three or four tries, whereas before I replaced the chain it never took an entire engine revolution, it always fired IMMEDIATELY. Could replacing a timing chain have anything to do with tossing off my base timing? Thanks!
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Unread 02-08-2010, 07:04 PM   #60
laybackman
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Quote:
Originally Posted by yellowoctupus View Post
Hi, I just replaced my timing chain (91 4.0), and the truck seems to run fine now, but is a bear to start. Sometimes it will just fire immediately, but more often than not it acts like the timing is super advanced (I think), it will spin for a while then pop, which just stops the engine spinning over, it's been taking three or four tries, whereas before I replaced the chain it never took an entire engine revolution, it always fired IMMEDIATELY. Could replacing a timing chain have anything to do with tossing off my base timing? Thanks!
Try asking this in a thread you started.Tgis thread is quite old.

Throw a timing light on this engine. See what the timing light says. You may have the timing off by 180*
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