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1964 Valiant Missing

Got a 64 valiant and have been having an issue with it lately at highway speeds. Occasionally at highway speeds it will start to run erratically and lose power, sometimes sounding as if it is backfiring. I adjusted the carburetor and tried it again, no luck. Then I checked the timing, it was off after only adjusting it about 2 months prior. We readjusted the timing and it ran better but still had the issue. The timing was jumping around with the strobe light so I’m guessing the chain is stretched and I’m planning on replacing it but I was curious to see if you guys think that is why the car isn’t running erratically on the highway. Any thoughts?

Distributor may also be wore.

I agree with hd72mm. Assuming the basics are good (wires, plugs, points, condensor), check the distributor shaft for play.

A worn distributor was the first thing that popped into my mind also. Include in that the possibility of a malfunctioning vacuum advance.

Another thing you might add is to check for proper and stable vacuum with a vacuum gage. This’ll give you a good idea if the valvetrain is timed and operating properly. It’s pretty simple to do, the instructions will come with the gage.

I already checked the vacuum and it looked pretty good, 19-20 mmHg so I don’t think that’s the problem, the head was rebuilt not to long ago with hardened valves and valve seats. The vacuum advance is brand new and seems to be working quite well after checking it with the timing light. I guess I’m a little unsure of what exactly you mean by a worn distributor, are you talking about the shaft bushings or the springs and other components?

As point gap/dwell changes the timing moves with it. Check the points and the point cam, etc. An oscilloscope would be grreat if available, If the dwell ia too small the spark will deteriorate as RPMs increase.

Shaft bushings. I’ve seen a loose shaft cause the kind of erratic behavior you’re describing. The ignition timing and the dwell wander everywhere.

On my 1965 Dodge Dart, a similar car, the distributor shaft bearing went at 30,000 miles and had the be replaced. It threw off the timing. I would definitely check the distributor shaft for play and check the bearing.

You were dead on with the timing mark jumping all over the place being the timing chain is stretched. I’d fix that first and then move on to the distributor. What engine are we talking about here anyways? And what year if it was changed? Any upgrades like electronic ignition?

It’s got the original 225" slant six, ignition is stock. I went through replaced the condenser, points, coil, cap, rotor etc. a few months ago.

Ignition wires OK? Sounds like You covered everything else . . . start simple and then go harder . . . re-check the point gap, rotor, cap, plugs, wires, condenser, timing and then check the distributor. Rocketman

Yeah, wires and plugs were replaced as well. I figured I’d reset the dwell and replace the timing chain and see what happens.

I’m of the opinion that if the timing chain were stretched, the camshaft would be off a few degrees but the ignition timing would not be jumping all over. There is enough drag on the chain from the camshaft that the chain would always be “under a load”. It would just lag and not jump around.

If you grab the distributor shaft and move it left-and-right, can you feel any play? If so, I’d fix that first (new bushings or get a rebuilt dist).

I welcome other input on the ability of a worn timing chain to allow the camshaft to get ahead of itself (as measured by the ignition timing moving around). I’ve been wrong before.

The bushings ended up being fine. It turned out that the points were shot even though I replaced them just a couple months ago. I made the mistake of getting the cheap points and they were toast. After replacing them with a decent set, resetting the dwell and the timing, the car runs great and the timing doesn’t jump around and haven’t had any issues driving at highway speeds. I’ll keep an eye on things, I’m wondering if the ballast resister isn’t doing its job and if that’s why the points died so quickly.

A faulty condenser can kill a set of points. Did you replace the condenser and if so, was it one with the proper rating?

As to the resistor, you should have 12 volts at the coil when starting the engine and about 6 volts when it’s running.

If the points were toasted in a couple of months then there’s a problem that is contributing to that toasting. Odds are it’s not caused by cheap points.

Full battery voltage to the coil when running will fry the points. I have seen people put a jumper wire to bypass a bad ballast resistor to get a car running and think the fixed the problem. The ballast resistor is the small rectangular ceramic block on the firewall.

A very good post that shows the danger of skipping over the basics and jumping into the exotic. It would have been real bad to put a timing chain on and still have the same problem. You need to totaly eliminate the ignition system as a source of driveability issues with these cars as thats where the problems most commonly are.

Points would have been my first step too, but I got here late.

A couple of weeks ago I ran into a kid at the local Autozone who was driving a nice '64 Ford Galaxie. He’d been told to replace his coil, which didn’t fix it. Then he’d done cap and rotor and was headed back to buy new wires. He’d never even HEARD of points, and apparently his official family auto guru was too young too. I popped the cap and could easily see that the points were almost closed all the time. A pocket multi-tool and 30 seconds worth of “eyeball” setting later had it running perfectly. Now I have a new car-guy friend and potential future customer. He thinks I’m right up there next to God.

Ignition points were always a suspect when an engine ran poorly back in those days. Ford also put the distributor at the front of the V-8 engine which made examining the points easier. The 1954 Buick and 1955 Pontiac V-8 cars that I owned put the distributor back against the firewall which made examining, adjusting and replacing the points more difficult. I’ve scraped down ignition points with a pocket knife and set the gap with a thin dime and had my old cars running. On the cars I own today, I’m not even sure where the spark plugs make their home.

Always best to start simple first . . . having grown up adjusting points I agree with the others . . . basic to exotic, simple to complex. Glad you got it figured out. Rocketman