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Help me set timing

950 views 8 replies 3 participants last post by  Goku 
#1 ·
OK, I am working on 89 YJ, 2.4 ...history unknown. I did tune up and then did Nutter. I checked timing. It was way advanced based on light and notch. I then set timing with vacuum gage ...and locked down distributor with engine running well and vacuum near maximum.

However the light then showed notch advanced by about 60 degrees. How is this possible?? Thanks
 
#3 ·
I marked the pulley and continued to check timing until I had a mark at 8 degrees. I then measured with flexible tape the distance from 8 degrees to the notch. I measured the diameter of the pulley and figured the circumference and divided up the degrees coming up with 58.8 degrees separation. There is considerable room for error in this but this is close enough to state the problem.

What has been done mechanically to cause this? If I knew the exact cause of either the engine or me ....then I could set timing on the money. ????
 
#4 ·
The 89 has the carb, not the TBI, correct? Does it run?

You say you put a mark on the pulley, and then found where the mark hit 8 degrees. Why are you doing this? (ie, why are you trying to time an arbitrary mark?) When the mark is at 8 degrees, what is the status of the other parts of the engine?

It kind of sounds like the distributor is "stabbed" incorrectly, and you should take it out, then line the pulley with 0 BTDC, then restab the distributor to be pointing at #1 plug.
 
#5 ·
robertdjung said:
The 89 has the carb, not the TBI, correct? Does it run?

You say you put a mark on the pulley, and then found where the mark hit 8 degrees. Why are you doing this? (ie, why are you trying to time an arbitrary mark?) When the mark is at 8 degrees, what is the status of the other parts of the engine?

It kind of sounds like the distributor is "stabbed" incorrectly, and you should take it out, then line the pulley with 0 BTDC, then restab the distributor to be pointing at #1 plug.
good answer.

While we're on the subject of timing... what is the timing to be set at for the 4.0L? I checked on the sticker under the hood and it says something about "no adjustment needed"
what's with that?.

I want to time it...(it backfires sometimes when I shift at high rpms), but I'm unsure of the setting. I haven't gotten a Chilton's for it yet... so I figure I'd ask you guys...

Is this backfire even caused by incorrect timing? -it only happens when shifting , and only if the rpms are kinda high (above 2k)
 
#6 ·
Yes, the 89 has carb...that is one of the reasons that I did the Nutter by-pass

Why the mark at 8 degrees? My timing light showed no notch. I then made some reference marks on the balancer to see where I was. From that I found one of my reference marks that lined up at 8 degrees with my timing light.

I then made my measurements from my reference point to the notch ...that is where I came up with about 60 degrees advanced.

OK, the Jeep runs good ... I locked down dist. with the vacuum on the low side of normal ...since I wanted the timing retarded rather than advanced ...(no knocking) Tonight, I shall find TDC on #1, and see where the distributor is set.

Thanks ... but keep any ideas coming.
 
#8 ·
robertdjung said:
sounds good, OEM. I'm about out of other ideas, I have the TBI and that's giving me plenty of headaches.

Goku - your fuel injection/computer controls the timing via sensors and what not, so there's nothing you can do to change it.
OK.... Thanks....
I wonder why it sometimes backfires while shifting at high RPM....
 
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