Don't knock the 3Rs

[Dana67Dart]

So I was going to a car show today an hour from my house...

I got 1 block from the show entrance and my engine died.

Crank and would sometimes fire but would not idle unless full throttle. Then it would start and idle but the moment you gave it some gas it would die.

Got out and pulled the air cleaner off, gave it a pedal crank and it shot a good stream of fuel, so the carb had fuel.

Checked the dist, it was bolted down tight.

I Happened to have a timing light with me, hooked it up and I could see timing flashes at about 0 to 5 right about where it was set.

Now it would not fire at all.

So I pulled the dist cap (it's a 67 Prestolite dual point small block dist, aka Commando/charger)

Center contact looked almost new, posts looked great, rotor looked great and points looked great.

Everything was tight.

As I was putting the rotor back on I did notice something.....

Some of you know what the issue is and are laughing right now!

The dual point breaker plate rotates on a bearing around the centerline of the dist shaft (unlike the off center pivot on the single point and electronic dist.)

Bearings are a poor conductor so there is a ground wire that connects the breaker plate to the body of the dist and to ground.

Well this dist was missing that ground wire when I got it so I made my own out of copper brade like the engine ground strap only smaller.

The wire was in its place but broken. SO... Under some vacume conditions the wire would touch and sometimes it would not.

This makes total sense now... Full throttle low RPM little vac advance the wire makes contact, closed throttle high vac advance the wire makes contact, anywhere between and the wire breaks contact.

So i pulled the rotor and set it on the inner fender behind the windshield washer bottle and got looking for some wire.

Oooooh! I have headphones in the glovebox, and no wired devices to plug it into anymore, perfect!

As I pulled the baggie with the electronics out a 3x5 paper tag, the type with 6 inches of wire to twist around a car part for identification fell out of the glove box ....

Lightbulb moment.

I cut the twisted wire off the card, twisted it around itself and made a u at one end. Not having a dwell meter with me I did not want to loosen the screw on one end of the original ground wire as that would also loosen one of the points, so I loosened the screw that holds the condenser on and put the u bend under that screw.

No how to attach it to the housing... No really good way that I could see so I just wrapped it around the screw on lug terminal and wrapped the remaining ground strap around the suspended bare wire

Not wanting the breaker plate to move i disconnected the vac advance hose.

I figured that ought to do it.

I put the cap back on (yep some of you know where this is going)

And cranked it over, nothing, nada, that's it I'm done! I'm going to call a tow truck.

Luckily my buddy Steve was there and as I was about to finish buttoning things up and make the call he holds up the rotor, you know the one on the inner fender behind the windshield washer bottle.

Oh crap!

I put it on and gave the car a crank and it fired right up as if nothing had happened.



So what are the 3 Rs....

Roadside Redneck Repair!

Don't forget them. They work!


Got to the show and had a great time!


Time spent on the side of the road 10 minutes!

Got to the show and had a great time!

Hot as hell but with 23% humidity was not bad

 

[Mattax]

That little braid tried to put a crimp in your day.

 

[jos51700]

Man, you points guys are hard core. I wouldn't knock a '69 Nats Concourse Resto if it had an orange box on the firewall. Electronic is so much simpler! Good job on figuring it out and also for catching that missing rotor....it would've rattled out on the tow truck and REALLY made it difficult to diagnose later.

 

[67Dart273]

Good job on both the diagnosis and the fix

 

[Dana67Dart]

Man, you points guys are hard core

They work! (Most of the time)

Electronic is so much simpler!

Technically but if it fails... You can't fix it on the side of the road with a scrap piece of wire!

 

[Dana67Dart]

I wired up a temporary fix till I get a replacement wire. I used 18 awg lead wire and soldered it to the remains of the lugs.

It fired right up. I backed it on to the sloped drive way. The decided to increase the initial since I was leaving the vac advance disconnected.

Got the advance set but the file speed was too high so I took some rpm out of it. Then it died.

After some cranking it restarted but was WAY down hill from there. To the point it would not fire.

I diagnosed it to a grounded point, it was open but grounded?

So having two I removed the offending point and safed the lead to it.

Adjusted the timing and I got it to start but it would not run. I had the old dist but had disassembled it for rebuild "someday" so I reassembled it and son I nailed the plastic keeper on the shaft putting the roll pin back in.

Crap. It's getting late and the storm clouds are looming. So I pulled the plug and called a tow truck to put the convert back in the garage.
Believe me if I could have punched it I would have.

The next day I had a lightbulb go off I had another dist.....

Set it in with the rotor pointing the same direction as the dual point, moved the wires over and put the remote starter switch on the relay.

Turned on the key and with timing light in hand hit the button, about 12 initial and fired right up.

This is temporary and I did not want to drill any new holes so out with the washer bottle and in with the Mopar orange box.


I don't notice any difference between it and points.

I was concerned about the additional load so I did a test. The orange box adds 200 ma (0.2A) to the system so I'm no longer worried.

Drove it to get gas and everything is was a ok.

Tomorrow I'm going an hour away to a car show

Fingers crossed!

 

[Mattax]

Vacuum advance or no vacuum advance, the initial stays the same or damn close. Some smog era carbs allow a tiny bit of exposure to the timed vacuum port. That's why the factory instructions always say to plug the vacuum line when setting initial. Sometimes they also instruct to put a small load on the engine. For example 600 rpm with the lights on.

To get pre-smog era initial timing with a smog distributor that has a long advance is to use manifold vacuum source instead of timed vacuum port. It may not be the best method, but often is an easy answer. IIRC your 'vert was a CAP car. But don't take a distributor intended for 0 or B* BTDC at 700 and set it at 12* at 700. That will be too much timing under high load (heavy throttle) above 1500rpm.

 

[Mattax]

Here's the specs for timing 49 state and CAP if set at the initial of 10 degrees at 600 rpm.

Changing the initial shifts the timing curve for all rpms.
Plus minus 2* initial was allowed for depending on local conditions and fuel.
My guess is that adding 5* would be about the limit depending on local conditions, and how the engine is built. If its closer to true 10.5:1 then its not going to want or tolerate the additional lead time under high load.

Fiddling with the throttle position changes the relationship of the transfer slots, which in turn changes the idle and off idle fuel mixtures.
The idle mix can be trimmed to some extent with the idle mix screws. The off idle can not be, so we can't go too far in changing the initial throttle position.

Holley idle mixture screws

Holley spreadbore 650 on a stock 318 and has the stock #56 jets in carb and 9.5 PV, it idles best when the mixture screws are all the way in. Could it have too small of jets in the carb? Should I bump them up a few jet sizes?

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