IS MY DISTRIBUTOR DEFECTIVE?

[FJ5 1970 440]

So this all started with run-on and wide open throttle issues. Didn't have a timing light to start with so I was retarding the timing in small increments and then running and driving the car. Results were going in a good direction. Got a timing light and found out it was at about 8* AFTER TDC. Doesn't make sense. So I tried 12* BEFORE TDC like most people seem to run and my cars problems multiplied. not only that but total advance was so high I couldn't even see the mark. So, is my distributor junk or has something slipped out of adjustment or what? The motor doesn't run hot, has 140 PSI compression, gas is good and plugs look good. Can I just keep on retarding the timing until I find the sweet spot?

 

[rarefish]

You should check to see if the timing mark on you balance is off. That will require a TDC check using a piston stop on #1 cylinder.

 

[Chryco Psycho]

If the outer ring of your damper has slipped the marks can be off .
This is why I never use a timing light but instead to engine to where they run the best .
I would look at the damper & maybe replace it before you have a bigger problem , also check the play in the timing chain by rotation the crank left & right , you can feel when the extra load of the cam comes into play , if there is a lot of degrees of movement the chain is loose & should be replaced , it may have jumped a tooth causing the engine to run poorly it will also run poorly if the chain is very loose .

 

[CudaGapCuda]

Sounds like a tooth off on your distributor or like Chryco says a time chain loose or skipped. I would bring up the timing mark on the balancer and check the rotor in distributor to see if its pointing at number one. I have also been able to starts an engine when the timing is 180 out so that is also possible.

 

[FJ5 1970 440]

Sounds like a tooth off on your distributor or like Chryco says a time chain loose or skipped. I would bring up the timing mark on the balancer and check the rotor in distributor to see if its pointing at number one. I have also been able to starts an engine when the timing is 180 out so that is also possible.

Got it to TDC and it looks like the rotor is in contact but slightly past center of #1. Does that make it a slip? Does a slip always go the same way? I understand that the valve train & ignition would be slightly ahead of the crank & pistons. Is there a performance benefit to this? Or, what kind of symptoms would this cause? If I am truly seeing this correctly my gut feeling would be it's an assembly error... Thanks..........

 

[CudaGapCuda]

I came into this thread a little later then most so I'm not sure what engine you are working on. So when you say the rotor is slightly past center of #1 plug terminal and don't want to insult you but just wanted to make sure you know the rotor spins Counter clockwise viewing from the front of the engine if it is a 440 and it spins clockwise if it is a 340. I'm not sure if a timing chain jumps if it always advances. The two situations that are running through my mind is the distributor could be one tooth off or the timing jumped one tooth or was installed one tooth off.

 

[FJ5 1970 440]

I came into this thread a little later then most so I'm not sure what engine you are working on. So when you say the rotor is slightly past center of #1 plug terminal and don't want to insult you but just wanted to make sure you know the rotor spins Counter clockwise viewing from the front of the engine if it is a 440 and it spins clockwise if it is a 340. I'm not sure if a timing chain jumps if it always advances. The two situations that are running through my mind is the distributor could be one tooth off or the timing jumped one tooth or was installed one tooth off.

Hey CGC; It's a 440, and I know rotation and firing order. Thanks, we're good. Just trying to sort out some strange timing issues, run-on and poor full throttle performance. I didn't build this motor so its pretty much a mystery.

 

[heminut]

Got it to TDC and it looks like the rotor is in contact but slightly past center of #1. Does that make it a slip? Does a slip always go the same way? I understand that the valve train & ignition would be slightly ahead of the crank & pistons. Is there a performance benefit to this? Or, what kind of symptoms would this cause? If I am truly seeing this correctly my gut feeling would be it's an assembly error... Thanks..........

The position of the rotor in relation to the #1 plug terminal has nothing to do with whether your timing chain may have jumped a tooth, the position can be changed by rotating the distributor, so there is no way to know if the timing chain has slipped by looking at the rotor position. Same thing with the distributor being put in one tooth off, that can be rectified by turning the distributor.

 

[FJ5 1970 440]

I think some more carb tuning is in order and if that doesn't yield the desired results the timing cover is coming off to check for a skip or what I suspect is an assembly error.