Spark and Timing.

[Offcenter12]

Hoping this is the best forum to use as a lot of great builds show up under this heading. Basically stock rebuild on 460 Ford with same distributor prior to rebuild. Installed with No. 1 on TDC but spark is occurring between contacts on cap. Different ignition modules, coils, pickup coil, and reluctor all have same result. Turn cap (carefully) half inch with truck running and runs fine. Cap installed in notch of distributor, apply vacuum and and misfires or dies. Rotor and pickup coil are between cap contacts when spark occurs. I just can't think of what's going on. Any help greatly appreciated!

Thanks,
John

 

[BajaScout]

Just guessing, but maybe the timing chain/gears were not lined up correctly during the rebuild?

 

[Bondo]

Installed with No. 1 on TDC but spark is occurring between contacts on cap.

Ayuh,..... What does this mean,^^^

If the rotor ain't pointin' at the #1 tower, yer probably off a tooth,.....

Unfortunately,..... I'm a Chevy guy, not a Ford guy,.....

 

[greg13]

Sounds like a tooth off, remember that when you set the distributor down in the block the shaft turns with the helical gear.

 

[Capt Crash]

You don't want it to fire on TDC. You want it to fire at 16-36degrees (depending on the ignition setup, and advance) BEFORE TDC. Set the distributor to where the truck runs and idles, then put a timing light on it and set the initial timing to what the book says.
Brian

 

[Boilerhouse]

Sounds like a tooth off, remember that when you set the distributor down in the block the shaft turns with the helical gear.

This crossed me up with a Dodge I once had apart, The marks were aligned before the distributor went into the block, but it did not take into account the helical shape of the gear. To get the thing to fire properly, I had to misalign the marks by a tooth, then drop the distributor into the block.

 

[junkyardwarrior]

Does the box grommet color match the distributor harness grommet color? If not, they should. It can make a difference (mostly because of the ground or lack of it issue). Also make sure the reluctor's pin isn't missing. Could the pickup be "bad"? That would be rare. Also look at the box's white wire. I think it's white. That wire retards timing while cranking when +12v is applied. Make sure it's not got +12v on it all the time, if it does, that can cause issues.

 

[Offcenter12]

Thanks to everyone for your replies. Just to clarify, initial timing is 10 BTDC with a light. Without getting into the specifics everything I've read states the distributor doesn't care where it's installed as long as the rotor points to No. 1 with No. 1 cylinder on the compression stroke, but have it with the vacuum canister facing forward.

Junkyardwarrior - It's a Duraspark 2 with the blue grommet and new reluctor and pickup coil.

Starting to descend into the depths of rotor phasing and vacuum canister arm lengths.

 

[joe49]

Did you change the distributor parts before you started the engine? Or as attempts to repair the trouble?

 

[Offcenter12]

No, this all started when the original distributor started doing all the crazy stuff. Question though, this is the original 1979 engine that came from the factory with 6 degree retarded timing for emissions. The shop rebuilt it to pre-emissions specs without the 6 degree retarded timing. Am I missing something there?

 

[APEowner]

To clarify; you're saying that if you change timing manually then the engine responds as expected but when you apply vacuum to the advance canister the engine dies?

If that's that case then the most common cause is a bad pickup or pickup wire that opens electrically when the plate moves.

It's possible that you have a distributor cap or rotor that's miss phased although I've never seen that happen with a Ford engine.

Another thought is that the tip of the rotor isn't wide enough. I have seen some cheap aftermarket ones that didn't have the broad tip of the originals.

One other item worth investigating is if the vacuum canister is actually an advance. Some smog era motors had a vacuum retard that used a convoluted vacuum control system. I don't remember if Ford ever did that on any of the 460 applications but if they did and you hooked that distributor directly up to ported vacuum it would behave weirdly.

 

[LXCam]

Before you go deeper you need to set the initial timing with the vacuum advance hooked up. Otherwise you're far too retarded for it to work hooking it up afterwards, nothing personal

Just remember you're highest vacuum is at idle so the system goes to full advance at idle then backs off under throttle.

Past that as mentioned it sure sounds like you're a tooth off.

 

[Offcenter12]

Before you go deeper you need to set the initial timing with the vacuum advance hooked up. Otherwise you're far too retarded for it to work hooking it up afterwards, nothing personal

Trust me, I'm beginning to feel pretty "mentally disabled" as the current term seems to be. Will check the white wire for 12 volts, ported vacuum, and everything else. Some for the 3rd or 4th time.

 

[ckcorder]

any update?? curious.

 

[RWorth]

offcenter, do you have a picture of your rotor?

Eric

PS. I just read threw the posts, it doesn't matter what tooth the distributor is on, you can set it up anyplace as long as you move the wires in the cap so #1 is facing the rotor around tdc on the compression stroke. You only have to skip a tooth or rotate the wires if you can't line it up where you are. That being said it's a good idea to line it up according to the book just so the next guy in line doesn't have issues. That and some of the caps are marked for #1 so it makes it easier for everyone if it's in the right place. The other thing I noticed is I have NEVER seen and old Ford that said to set the initial timing with the vacuum line connected, they always want you to plug the vacuum line to set the timing.

 

[Offcenter12]

any update?? curious.

Good timing, bad joke. And RWorth, you're correct. APEowner above nailed it, just couldn't believe two new parts were bad. The problem was two new aftermarket Standard Motor Products pickup coils wired in reverse! After finding a thread on another forum having the same issues the individual jumped the wires and it ran fine. The truck is in a friend's shop and when he did the same it worked. I found an OEM Ford pickup coil and problem solved as of today. Never would have guessed that in a million years. He's taking the two pickup coils back to the parts store and explaining the issue. Not sure if they have any recourse with the supplier, but sure wouldn't want someone else to end up with them. Usually pretty confident in Standard parts, but QA sure missed the boat on these. Thanks to all for checking in!

John

 

[ericlar80]

Before you go deeper you need to set the initial timing with the vacuum advance hooked up. Otherwise you're far too retarded for it to work hooking it up afterwards, nothing personal

Just remember you're highest vacuum is at idle so the system goes to full advance at idle then backs off under throttle.

Past that as mentioned it sure sounds like you're a tooth off.

This is completely incorrect. You need to set base timing without vacuum hooked up. As the engine RPM climbs, the timing will increase (advance) so that full ignition occurs at the right moment.

The tooth location doesn't matter if you an old system. If you have a computer controlled system with a reluctor wheel, it begins to matter. What year engine are we talking about? Does it have a TFI module?

 

[TommyK]

No, this all started when the original distributor started doing all the crazy stuff. Question though, this is the original 1979 engine that came from the factory with 6 degree retarded timing for emissions. The shop rebuilt it to pre-emissions specs without the 6 degree retarded timing. Am I missing something there?

It was the valve timing that was retarded from the factory. Don't confuse that with ignition timing.

Have you verified TDC on the balancer? Put the number 1 piston at TDC on the compression stroke (both valves closed) and see if the timing pointer is at zero on the balancer.

 

[TommyK]

Before you go deeper you need to set the initial timing with the vacuum advance hooked up. Otherwise you're far too retarded for it to work hooking it up afterwards, nothing personal

Just remember you're highest vacuum is at idle so the system goes to full advance at idle then backs off under throttle.

This is only true if the advance is hooked up to full manifold vacuum which on a Ford it probably isn't.