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Timing mark moves

6K views 33 replies 6 participants last post by  flatwater 
#1 ·
I am still struggling with this trooper. I have swapped out the I-Tec for a Weber carb. I started out with a junk yard distributor when I performed the swap but could not get it to run great. it would seem to idle fine but run terrible under load. While setting the timing, the mark would be steady at about 10 btdc and then would disappear. today I installed a brand new dizzy and got it running. It seemed to idle fine until I got it warmed up. then it would have an occasional very small stumble every 10 seconds or so. It was not anything major but as I was trying to set the ignition timing, the mark would do the same thing. I put the timing light on it and it would seem to hold steady and then disappear for a couple of seconds. I found it clear over at about 2 o'clock (pointed towards the exhaust manifold.} then it would return to 8-10 btdc.

what could be causing it to do this? I have never had so many weird things go on trying to get one vehicle running.

thanks in advance for the help.
 
#27 ·
First: I re-read the whole article (man, I really need a life :roll:). A few suggestions: #1 and #3 are together at the bottom of the distributor cap. A crack (even very small) can cause tracking, I know you have tried 2 caps, either one new? It is possible to have a defective cap - even 2, but I am not suggesting to throw more money at it yet. Agree on the vacuum test. A number of things can cause a vacuum leak - which causes a lean condition - which can cause a lean misfire situation.
Moore questions: (have to ask). What about valve adjustment? compression test? Can't rule ANYTHING out. Most Webers have the electric idle solenoid. Does yours? Is it hooked up to power? (sorry, but again have to ask). Have you opened up the carb to have a look inside (dirt can easily clog an idle circuit. My thoughts. Dennis
EDIT: really have to laugh. While I was typing my reply, Ed was on the same wave length :D . D.
 
#28 ·
Dennis,
That is funny! We must have had the same thing to eat for breakfast.

/tim

EDIT: I guess Ed and I do write in a similar manner.
 
#29 ·
Just for clarity. When I closed the choke and the idle increased, the timing mark stayed steady vs. moving back and forth.

So closing the choke did not kill the already warmed up engine so I did some spraying of carb cleaner around the base of the carb and the mating surface between the intake and the head and I definitely am sucking air in a few places. Gonna see if I can get it sealed up better with some new gaskets. And then resume trying to get this tuned.
 
#30 ·
Sounds like a plan! Keep us posted.
 
#31 ·
Vacuum leaks - especially fluctuating vacuum can cause the timing to bounce around. It shouldn't, because the vacuum should be hooked up to ported vacuum, but that's a perfect scenario.

Corned beef hash, fried eggs, grits, coffee. :D Dennis
 
#32 ·
But his vacuum advance should be disconnected while setting timing, correct?
 
#33 ·
kg4miq said:
But his vacuum advance should be disconnected while setting timing, correct?
you're right. He did have it disconnected. Hmmmmmm. Dennis
 
#34 ·
Dennis,.

I have been saying hmmmmm all week.

I missed some of the comments on here since I have been trying to work while distracting my self with musings of erratic timing...

They are NGK standard plugs. The first set was platinum but I swapped those out a couple of months ago.

At any rate I need to get the air leaks sorted out before I can move on.

Thank you very much for everyone's help with this. I know it takes time from your day to respond and I am very grateful. Eventually this will be sorted out.
 
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