[WINGNUT]

I'm trying to adjust the timing on my GTO now that I have a properly tuned Q-Jet sitting on it. Should the vacuum advance line be pulled off during the setting of the timing? Every time I pull it off, it stalls. Does that mean that the timing is too low to begin with?

Plus, there are two EGR lines that go into the engine, but I have no idea where they plug into. The vacuum advance line plugs on the top front of the Q-Jet, and there is one more tube on the bottom of the Q-Jet to plug a line into. But I'm not sure what goes there. It appears I need one more tube on the carb to attach the last line, but there isn't one. Any thoughts?

Thanks!

[engineer]

the factory service manual has answers to both of these questions. How to adjust the timing and what ports the vacuum lines should be connected to. Try those first and let us know what the results are.

[wheelspin]

Engineer,

Since you obviously have all of the books, why not answer the man's question ?


Wingnut,

Timing is adjusted with the vacuum line off the distributor and plugged. Raise the idle slightly, if needed, to prevent the motor from stalling when setting the initial timing. If you need another vacuum port, a "T" fitting in an existing line will suffice.

Les

[amcmike]

Originally Posted by wheelspin

Engineer,

Since you obviously have all of the books, why not answer the man's question ?


Wingnut,

Timing is adjusted with the vacuum line off the distributor and plugged. Raise the idle slightly, if needed, to prevent the motor from stalling when setting the initial timing. If you need another vacuum port, a "T" fitting in an existing line will suffice.

Les

And yes, if the vacuum port is plugged (so it's not an air leak) and the engine doesn't like to run on just the initial, you probably need more timing.

[Cardo]

Typical engineer right?

[WINGNUT]

Thanks guys! Unfortunately, I ran into another problem while trying to adjust the timing. I finally discovered a short in the wiring harness that I have suspected I had a while ago but was never able to locate until today when it caught on fire. So the timing will have to wait until I order a new engine harness from PY. I have a question about that also, but I'll create another thread.

But speaking of timing, for some reason I wasn't able to see the marking on the harmonic balancer when I shot the light on it with the engine running, so I couldn't line it up with the scale. I didn't have this problem the last time I messed with the timing, is this some sort of phenomenon? The markings are all clear, clean and legible. Plus, before I had to shut the engine down because of the fire in the harness, the idle was extremely low, even with the distributor turned all the way clockwise (advanced) any thoughts guys?

[WDCreech]

"Plus, before I had to shut the engine down because of the fire in the harness, the idle was extremely low, even with the distributor turned all the way clockwise (advanced) any thoughts guys?"

You've probably got the distributor in one tooth off.

[WINGNUT]

I just thought of something and I feel stupid for not thinking of this earlier. Could the curb idle be set way too low?

[WDCreech]

Question; When you advanced the timing to get it to idle, what did the timing marks tell you that it was advanced to?

[WINGNUT]

The last time I set the timing was about three two years ago, and I had to retard it a bit. I can't actually remember what I had set it at unfortunately. I was able to see the mark and adjust according to the timing scale. I can't figure out why I wasn't able to see it with the light this time.

[WDCreech]

Like I said in my first post, "You've probably got the distributor in one tooth off."

[Formula jg]

General inquiry about the 'one tooth off' possibility.

I know to bring the #1 piston to TDC and check that the rotor points to the #1 firing plug @ the cap, but how do you know its out just one tooth?

How far off is the rotor from pointing to the #1 plug when its out one tooth?

One more question or clarification, it was mention in an earlier post that if the engin does not run on initial timing then the initial is too low (actually I should probably start a new post for this one).

Thanks all

[Juliano]

I think your dentist can adjust the one tooth out on the cam gear.

[Paul E]

If the idle for the timing is correct, and you remove the line (should plug line to prevent vacuum leak) and the engine kills the mixture is very lean. A good check for idle mixture is set mixture, then remove small vacuum line and create a leak.

Die= lean
Speed up= rich
Stumbles= pretty close

Lean is the worst condition

Paul

[Will]

If the distributor is in a tooth or two off all that will happen is that you may not be able to rotate the distributor body far enough to get the timing set where it needs to be before the vac advance hits something.

Since you were able to see the timing marks before and had the timing adjusted, it's unlikely the distributor somehow magically jumped a tooth.

Get the wiring harness back in and leave the vac. advance unhooked and the vac port on the carb plugged until you have the engine running the way you want. Then you can start playing around with the vac advance.

The purpose of vac. advance is to help the engine run more efficiently during part-throttle cruising when AF ratios are very lean. It helps improve gas mileage and that's about it. A well tuned engine with an appropriate timing curve should run just as well in normal driving with the vac can hooked up or not.

[amcmike]

Actually he hasn't told us if he ever removed the distributor or not. Didn't mention changing any other components (cam, intake) either. Would probably be good information.

[68WarDog]

But speaking of timing, for some reason I wasn't able to see the marking on the harmonic balancer when I shot the light on it with the engine running, so I couldn't line it up with the scale. I didn't have this problem the last time I messed with the timing, is this some sort of phenomenon? The markings are all clear, clean and legible. Plus, before I had to shut the engine down because of the fire in the harness, the idle was extremely low, even with the distributor turned all the way clockwise (advanced) any thoughts guys?[/QUOTE]
How old is your timing chain?

[Formula jg]

So if the distributor was removed with the rotor at #1 TDC, then when re-installing the dist. you pop it in one tooth off (either advanced or retarded). Approx how far off the would the rotor be from pointing at #1 cap terminal?

[jku72]

It does not matter a bit if the distributor is one tooth off. All you have to do is rotate the distributor and then it will be in line. There is no set tooth location. I think either they are pulling your leg or they don't know, or are confusing the cam timing with distributor timing.
My car also did not have the timing marks even close, and it did stall also when I disconnected the vacuum advance. I then manually advanced the timing by a little, so that the engine would run. I used a dial back to zero timing light and found I had 31 degrees intial. Yes, it can run like that at idle. In fact it runs faster with massive initial advance at idle. With the engine now running, I slowly retarded the timing, and when the engine slowed too much, I increased idle speed, and so on, until I got to 15 degrees initial.
It is interesting to note that the first time I did it, the engine was so far advanced that I saw no timing light at all, until I ran my advance dial way up.
As one other person noted, it is possible that the distributor will hit the manifold or firewall if it is way out like this. In this case you can either lift out the distributor a little to disengage the teeth and rotate the dist. shaft, or, you can just shift the spark plug wires over one hole. Just be sure to go the right way, and keep the order correct.
On the other hand, the CAM can be off one tooth and cause havoc like this too. But the distributor does not care what tooth it lines up with.
Not all vacuum ports are used. On some cars I use manifold vacuum, and other I use ported. It really depends on what your idle speed turns out to be. Experiment, which ever one seems to work best, use. You can just plug the one your not using. Timing is set with the vacuum disconnected always. Usually when I set my initial correctly, and do all my other tuning, the last thing I do is vacuum advance, then it's like I said, whatever works best as to the port. NEVER reset initial timing based on what the vacuum advance does. When I did my pontiac, I connected the vacuum advance to manifold vacuum and my idle speed went up to 1000 rpm. So I connected it to ported vacuum, and hardly altered the idle speed at all, but for cruising I get the advance I need. Entire books have been written on this. It takes that much to fully understand the dynamics involved, I think.

[WINGNUT]

Thanks for the replies. No, I never lifted the distributor out of the block, I only replaced the cap, rotor, condenser, and points. The timing chain is about 7 years old.

Is the 'Dial back to Zero' timing light the one with the dial on the end? If so I do have one, I bought it over the winter but never used it. I was using the non adjustable type this time, same as last time.

I was going to post a question about how to use the adjustable light since I'm not really sure how it works. But since it was brought up, how do these work, and when do you use them?