Timing mark jumping around
10-03-2010, 09:19 AM
#1
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Timing mark jumping around
Sorry I need to post a new thread on this, but my other thread is too long on my misfire.
I notice when I try and set my timing, the mark jumps around about 5*. I have checked the distributor air gap and resistance per the FSM and they seem to be in spec.
I suspect its the timing chain, but I cannot be too sure. I don't get much of any rattle in the chain. I did however feel that the tensioner might be loosing some strength.
I think I've changed or inspected everything on this damn engine, and the timing chain is the last thing.
I notice when I try and set my timing, the mark jumps around about 5*. I have checked the distributor air gap and resistance per the FSM and they seem to be in spec.
I suspect its the timing chain, but I cannot be too sure. I don't get much of any rattle in the chain. I did however feel that the tensioner might be loosing some strength.
I think I've changed or inspected everything on this damn engine, and the timing chain is the last thing.
Last edited by BajaRunner; 10-03-2010 at 11:19 AM.
10-03-2010, 10:40 AM
#5
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10-03-2010, 10:53 AM
#6
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With the engine running...the torque on the chain wouldn't allow the cam itself to do that.
It could distributor related. How is the physical condition of the dist? A worn dist would cause this.
It could distributor related. How is the physical condition of the dist? A worn dist would cause this.
10-03-2010, 11:20 AM
#7
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Ok I took out the "g" in front of the damn since it apparently pisses off people.
Well the distributor seems to be fine. I have tested air gap and resistances. I don't know what else to check on it.
Well the distributor seems to be fine. I have tested air gap and resistances. I don't know what else to check on it.
Last edited by BajaRunner; 10-03-2010 at 06:46 PM.
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10-03-2010, 11:47 AM
#8
Registered User
Ok do me this test.
Check the timing for me...but do it from a cold start. Quicker you check it the better.
Then let it warm up to temp and check it.
Did it get worse as it warmed up?
Check the timing for me...but do it from a cold start. Quicker you check it the better.
Then let it warm up to temp and check it.
Did it get worse as it warmed up?
10-03-2010, 03:22 PM
#9
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I just went out and double checked some things on my dizzy. I found the rotor screws not very tight, not real loose either. I checked the pickup gap and reassembled, I put a little lock tight on the rotor screws. I grabbed the timing light and now my mark is steady as a rock. It was also about 4* too retarded, so I retuned it to about 11-12* and called it good.
10-03-2010, 06:39 PM
#10
Registered User
I'll bet camo was just horseing around, eh. One would hope......
The only thing I can think to check on the distributor is for play in the shaft. You have to pull it to check for it, though.
10-03-2010, 06:49 PM
#11
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Thread Starter
The rotor does go back and forth a little bit. The play in the shaft .. is that caused by the meshing of the gears (or wear between them?)
I didn't have time to start/drive or look at the motor today....
My timing kit is from enginebuilder w steel backed guides, I can't wait to get it in
I didn't have time to start/drive or look at the motor today....
My timing kit is from enginebuilder w steel backed guides, I can't wait to get it in
10-03-2010, 09:57 PM
#12
Registered User
I'm talking about lateral play of the shaft in the housing, not play in the gears meshing. A little of that is normal because of slack in the chain. You have to pull the distributor out of the head to check for this. When you do, grab the gear end of the shaft and wiggle it back and forth laterally......not up and down. There shouldn't be any play.
So, you haven't even put your new kit in? Oh. Why worry about the timing until then? Is it going to be a while before you can install it?
So, you haven't even put your new kit in? Oh. Why worry about the timing until then? Is it going to be a while before you can install it?
10-04-2010, 04:40 PM
#13
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Well no I can install it this weekend if I want to. I just was sort of trying to confirm that an old chain and tensioner would cause a jumpy timing.
It seems to me that the jumping moves more when its warm for sure.
Also I am a little concerned because the truck ran perfect the first day after I replaced my cam, head gasket, rockers, etc. Then 2 days afterwards it started being sluggish again. I thought it must be timing and valves...Well I doubel checked timing is at 5* (as best I could) and the valves are perfect. Also the head bolts and manifold bolts were re torqued.
Its not as sluggish as before but it still needs something. Will a timing chain really make a noticeable change? The guy who I bought the truck from gave me an enginebuilder timing kit and he bought it in 2008...making me believe its been a while since Its been (if ever) changed in its 145k life.
It seems to me that the jumping moves more when its warm for sure.
Also I am a little concerned because the truck ran perfect the first day after I replaced my cam, head gasket, rockers, etc. Then 2 days afterwards it started being sluggish again. I thought it must be timing and valves...Well I doubel checked timing is at 5* (as best I could) and the valves are perfect. Also the head bolts and manifold bolts were re torqued.
Its not as sluggish as before but it still needs something. Will a timing chain really make a noticeable change? The guy who I bought the truck from gave me an enginebuilder timing kit and he bought it in 2008...making me believe its been a while since Its been (if ever) changed in its 145k life.
10-04-2010, 05:00 PM
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Did you try another timing light? I actually had one go bad and the timing was moving around as I would shine the light. Tried a different one and rock solid.
Is your timing erratic when this happens or does it sort of slowly move around? When my timing light went bad the mark just jumped all over like each flash was in a different spot.
Did your idle drop when you jumpered the test connnector?
I have a hard time thinking the timing chain could cause this, or the tensioner for that matter.The tensioner is on the "slack" side of the chain, and if your just idling the cam can't rotate faster than the crank, which it would need to do to cause this problem. If your chain is way stretched out it certainly could cause a problem in drivability.
Is your timing erratic when this happens or does it sort of slowly move around? When my timing light went bad the mark just jumped all over like each flash was in a different spot.
Did your idle drop when you jumpered the test connnector?
I have a hard time thinking the timing chain could cause this, or the tensioner for that matter.The tensioner is on the "slack" side of the chain, and if your just idling the cam can't rotate faster than the crank, which it would need to do to cause this problem. If your chain is way stretched out it certainly could cause a problem in drivability.
10-04-2010, 06:07 PM
#16
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Andy: Yes, I have tried 2 timing lights actually 
Both do the same. Yes the RPM drops down when I jump the terminal. I have it set at about 850, with the jumper it goes to around 650 or 750.
HighLux: Ok well, I hope he's right.
Basically when its at idle, it has a little "bump" that it hits every few seconds. The timing jumps and the motor also jumps. I can hear it in the exhaust. I have been explaining this as being my misfire. After changing out every sensor and replacing my worn rockers and cam it seemed to fix it only for a few days.
Now when I hold RPM's at 3000 or so, the "bump" comes back, and the entire engine shakes. I don't hear much of any chain rattle, only when I am driving and let off on the gas.
Both do the same. Yes the RPM drops down when I jump the terminal. I have it set at about 850, with the jumper it goes to around 650 or 750. HighLux: Ok well, I hope he's right.
Basically when its at idle, it has a little "bump" that it hits every few seconds. The timing jumps and the motor also jumps. I can hear it in the exhaust. I have been explaining this as being my misfire. After changing out every sensor and replacing my worn rockers and cam it seemed to fix it only for a few days.
Now when I hold RPM's at 3000 or so, the "bump" comes back, and the entire engine shakes. I don't hear much of any chain rattle, only when I am driving and let off on the gas.
10-04-2010, 06:36 PM
#18
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Yes, this weekend I hope. I know I should have done it with the head off but I seriously wanted to just do one thing at a time. Sounds silly but I didn't wanna screw something up. :/
Plus, it doesn't seem that bad to pull off the timing cover. Do you have to drain the block from coolant? I can't seem to figure out how to get that plug off. No room with headers but I'll try. Or does draining the radiator work enough?
Plus, it doesn't seem that bad to pull off the timing cover. Do you have to drain the block from coolant? I can't seem to figure out how to get that plug off. No room with headers but I'll try. Or does draining the radiator work enough?
10-04-2010, 06:46 PM
#19
Registered User
Draining the rad should be fine...once you pull the lower hose....it will empty out enough.
My engnbldr stuff should be here tomorrow...I cant wait to get the 88 going.
My engnbldr stuff should be here tomorrow...I cant wait to get the 88 going.
10-04-2010, 06:57 PM
#20
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Yeah dude I couldn't believe how stoked I was to see that it was an enginbulder kit. He seemed like he had no idea about the truck at all. It also appears that he bought the new head from enginebuilder as well.
Should be great to get the new kit in!
What are you getting?!
Should be great to get the new kit in!
What are you getting?!
