Rotors are known to fail and the spark will ground through it to the dist. shaft. The other thing I have seen through the years is certain brands of caps have a spring loaded carbon contact in the center of the cap for the coil feed to the rotor, I have seen these fall out and or wear down ( the solid contacts like SBF usually uses do this at times) to the point of no more contact with the rotor. The cap is easy to check. On the rotor look for carbon tracking (dark spots or lines that indicate the voltage is going through the rotor)through the plastic towards the dist. shaft.

 

OK...spark goes into the distributor, but doesn't come out.

Since the rotor is there, check the metal tang on top of the rotor and the carbon button in the distributor cap...they need to be making contact.

If that makes contact, look at the tip of the rotor and the brass lugs in the distributor cap...the current arcs from the tip of the rotor to the lug on the dist cap, so sometimes those get beat up and corroded.

If it's not that, fall back to the timing. Rotate the engine to the top dead center position on the compression stroke. On your pertronics, there is a pickup device mounted adjacent to the 8 pointed magnet that is on the center shaft of the dist....that is the pertronics magnet and magnetic pickup. The pertronics replaces the points...it fires off a spark when one of the 8 points passes by the magnetic pickup. Position the dist so that one of the 8 points lines up exactly with the pickup...make sure that the rotor is pointing toward the place where the #1 spark plug wire attaches to the dist cap. This should have your timing at top dead center...it should start, and you can adjust it to specs with a timing light later.

Dan

 

I just tried attaching a light device to the spark plug and turned the engine over. The light is supposed to flash but doesn't so I guess this confirms the lack of spark out of the dist cap. The rotor resistance checks out and the cap looks fine and since it worked before I took the distributor out and just sat there waiting for it to come back I suspect it is fine too. If I hand crank the engine with my finger in the spark plug hole will there be any compression on the exhaust stroke? I suspect the primary issue is timing, could this be the whole issue?
Chris

 

Dan, We seem to be on the same page (your post are almost the same but for once I am beating someone to the punch)

Seawulff (this is where names are nice) and Dan, if there is spark the Petronix is working (I have had one for over 20 years) The magnet inside the Petronix collapses the field in the coil allowing the coil charge to exit the coil and flow through the coil wire to the cap, the cap is supposed to pass the voltage to the rotor to distribute it to the plug terminals in the cap where it exits via plug wires to the plugs. The timing is just that it only effects where the spark enters the the cylinder after doing the above. The timing will not have any bearing on spark leaving the cap, timing may be off but that will not change spark exiting the cap. So you are losing it somewhere inside the cap, that is where you need to look.

 

Chris,

I think you just found your problem. It is not a timing issue. If you have spark to the distributor from the coil (I think you said you did), and no spark coming out of the distributor, the distributor is where your problem is. It has nothing to do with timing if there's no spark.

EDIT: Dave, we were typing at the same time... And, maybe I shouldn't be commenting here, because I know nothing about Pertronix...

 

Chris, timing is not your primary problem. You have no spark exiting the cap. So either the current is arcing to ground or it is not making it to the rotor. Check for corrosion in the cap hole for the wires, maybe while sitting around it fell and got a small crack allowing the voltage to go to ground, something along those lines. Cap and rotor are cheap, you had the dist. rebuilt, start with a new cap and rotor.

 

Thank you Joe.

 

Yes...it looks like we were all typing at the same time.

I tend to agree with Dave and Joe...go to Napa and pick up a new cap and rotor before they close tonight!

Dan

 

My distributor had the exact same symptoms as yours. Did you put a ground wire (from vacuum advance screw to a known ground)? Just curious.

 

A ground issue seems reasonable. The ground wire runs from one of the screws that holds the pertronix to the plate it attaches too, to the side wall of the distributor. Is that the correct path?
Chris

 

I have never had to run an additional ground wire on a dist and yes that sounds like a correct path because it will then ground through the dist. shaft.

I still say it is the rotor or cap as long as you have spark out of the coil wire.

 

Chris,

I am referring to 2 grounds. The first ground is inside the distributor as you mentioned. The second ground should be from the vacuum advance screw to a known good ground. I realize this doesn't sound correct, but just try it and see what happens.

Here is a good read:

Ground wire on distributor makes engine last longer? - THE H.A.M.B.

 

Lance,

That's all good advice, but in this case, Chris has spark....the pertronics is doing its job and the coil is working.

The distributor isn't distributing. Spark is being supplied to the center lead of the distributor cap and it isn't coming out anywhere.

If everything checks out, there is another possibility. If you're off a tooth or so, the rotor could be pointing between two of the contacts inside the distributor cap when the spark goes off. If there is too much air gap, the spark might not be able to jump the gap.

Do your timing exercise again, and use a sharpie to mark on the side of the distributor where the rotor is pointing when everything is lined up for firing position (tdc on the compression stroke and the dist rotated to the pertronics pointy node aligned with the pickup module). Now put the dist cap on and see where the mark is compared to the #1 spark plug wire attachment....it should be centered up.

Dan

 

Well as NASA says, we have air, we have gas, we have spark and now we have ignition!. I'm not sure what I did but I'll tell you. I moved the ground wire from outside the metal plate that is on the screw holding it to the side of the distributor to between this plate and the distributor body, I also saw that part of the Pertronix metal housing was touching the distributor body so I moved that off of that position. After that I did have spark using the spark testing light. Then it was a matter of moving the distributor and rotor until it was lined up with TDC and jumping it since I had drained the battery trying to start it so many times. Damn it feels good. I think I got more satisfaction out of hearing that engine then I do a day/week at work! Thank you for all your help. Any suggestions on the appropriate timing for a 312 with an automatic transmission. I have read that 4 degrees ahead of TDC is good. Once again thank you for your help.
Chris

 

Congratulations on getting it started.