Doesn’t want to start after tune up

I'll ask the obvious. Did you verify firing order? verify the cap is on correctly?

Great question! And yes, the obvious one. I made this cheat sheet of the distributor connections when I did the first tune up, and yes, I’ve checked the wires TWICE! (Against the sheet 😬) Take a look and see if I did something wrong. The cap only fits one way with the cutout on the side (I think).

Last time I saw that happened… The person putting on the spark plug wires on the cap incorrectly! When you look down from the top, the rotor turns counterclockwise, not clockwise!!

…make sure that the rotor finger is pointing at the pick up for number one on the cap with cylinder 1 on firing TDC

Did you remove the distributor?  If so, you may have reinstalled it 180° out of sync.  

Also, check to make sure that the outer ring of the vibration dampener has not spun.  

John

Of course, you have heard of the stock distributor pin shearing…. I had a case where it didn’t shear completely, but enough to significantly retard the timing…

So anyway - that’s another thing to look at, but if you do the timing checks, as suggested above, you will find if that’s the problem…

Anyway, my real point in is that a sheared distributor pin doesn’t ALWAYS result in your distributor not turning…. It can still get bound up, and your timing will continue to retard, until it eventually fails completely…. But until it fails, you are chasing a timing problem..  you reset it,  and then a week later you’re having the same paganism!

Good luck!

Rocky

With dist cap off and rotor removed have someone crank the engine while you watch for sparking at one set of points. If no spark make sure that all the connections to the point are not grounded. Some people think that both sets of points should spark but that is incorrect. Only the last set to open will arc. Let us know what you find.

...A 'Good' Condenser is there to keep the points from Arcing. A 'Clean-Break' of the Current to the Coil is necessary for a Healthy Spark, through the D. Cap to the Plugs. With 'Arcing' of the points, there is Not a Total Collapse of The Magnetic Field within the Coil, That Creates the Spark. The Spark is Not Healthy. Should be a 'Blue Flame'.

Everyone is putting in Their Guess, of Which of a Dozen Failers can Cause a 'PoP', without Starting.

This guy has a lot of Searching, Testing, work ahead of him.

That's as far as I'm going. Don't Test the Coil Improperly and Burn it out!!

MJ

...After a Tune Up?? Re-Gap the Points. The Rubbing Block on New Points Has to wear-in...Especially if the Block and Cam have Not been Lubricated. This Closes the Gap Up.

The advantage of Dual points. (Dwell Duration=Coil Saturation)

MJ

I have found that the Ford dual point distributors that use the same design points cam (Boss 302, 351CJ, 429 CJ) for some reason unknown to me seem to wear on the internal portion of the points cam. (the pivot).

Now I only work on things that pertain to me. I am not a professional restoration shop so it seems obvious that my situations may not be common across the board.

In order to maintain accurate point settings throughout the distributors rotation, the clearance on the distributors drive shaft and the points cam need to be accurate.

IF the play between the shaft is greater then maybe .0005". the settings on the points will be inaccurate.

If the cam is wobbling .0005", the then setting on the points will be wobbling at least .001".

Now here is the point, take the cap off the distributor and push the points cam. If you feel it wobble, then it needs to be dealt with.

I have found the cam worn internally as much as .0050". That means that your point setting is off .0100". With that you will not get anything like an accurate coil firing because the points are going to be grounding all of the time.

Now I know that you posted that you set the dwell, but I don't know the method that you have used so there is still a possibility that you have excessive wear in the cam.

Now if after checking this for wobble, you find that it is there you have to deal with this. If you feel it, it is more then .0010".

Those cams have not been available as service parts for decades from Ford and virtually anyone else in the aftermarket.

The three engines mentioned all use vacuum advance along with the dual points and as such those cams are unique and not the same as in the earlier 289hp, 427's, etc.

There are three variations of them depending on the notches in them for the mechanical advance the specific engine uses. As far as I know, three different advances for three different engine families.

So the choices are two. Replace the cam with one that is not worn, if you can find one,  or repair the one that you have by knurling  and reaming it.

As it turns out the dimension is 5/16" and that is an easy knurler to come up with and the reamers are common as well, in both the standard size of .3125" or +.0001 or +.0002, etc.

It is something that you can easily do yourself with these hand tools. Nothing that NASA needs to do for you?

So if you have noticeable wobble in the cam, and you still won't fire with the dual point Ford distributor, investigate for excessive wear internally in the distributor.

Is this a completely bizarre thing to look for? Absolutely, but to some, the situation is right in front of them and completely invisible.

If you have already checked for this and you have no wobble, ignore this and go back and finish the video game you were playing. Just think of this post as an eccentric old guy substituting posting here for therapy.

I am sometimes concerned with this as well. Prefrontal labotomy keeps coming up in a reoccurring dream and I keep escaping the nurse that wants to stick me with that big hypo that she says will calm me down!

Thank you all so much for the help and advice. Looks like this guy definitely has a lot to do. I just hope I don't need to send her to the hospital..

panteradoug - that was great! Technically, I could have made a mistake during the tune-up since I did indeed have brain surgery last year. Something about removing a mass. They might have taken too much as I don't have much to spare.. :-)

I'll provide updates. (For your comic relief if nothing else.)

William

So, I pulled spark plug 8 and it has some deposits, probably carbon. The dry one is the one I replaced.

Ok, looks like there’s no spark. That’s good news because electrical I can troubleshoot, timing, not so much. Stay tuned ..

I don't know if it's relevant. But, the shop I worked years ago did a tune up on a car, which would not start after the parts were replaced. Turned out the condenser was bad, despite the shop using only brand name parts.

Richard O.

I’ll add that to my list. Thanks opiecars.

...It looks as if the Plug was NOT Grounded during the Testing! That is Exactly HOW You Destroy a Coil!! I Did Warn You!!

With NO Ground, the High Voltage 'Seeks' a Ground with-in the Coil, and Finds it To the Primary Wiring! This 'Burns' a Permanent 'Path' through the Windings that will Forever be a Short in the Coil! The Coil becomes Junk! The HIGH VOLTAGE Has to 'DUMP' somewhere...and it's To the Primary Ground, INSIDE the Coil!!  FWIW

Yup, the  coil is first on my list 👍. Thanks Markin.

Depends who you ask….😁

Thanks Marlin. (I was typing without glasses and missed the l and hit the k accidentally. Like I said, close but not quite all there.. 🤪)

I get good spark off the high tension lead from the coil, so I would say the primary circuit is good? If so, then the problem is in the secondary circuit.

Ok, Marlin was right, not only was the spark plug not grounded, neither was I. I’m (me) definitely not firing on all 8.😩

We do have spark.. 🫤