Packard Forum Index » V-8 (1955-56)

I have a lot of experience with 1960's and newer cars, but not with Packards. I want to run my problem and thought process past you folks who have more Packard-specific experience than I do to see if I'm headed in the right direction for these specific cars.

My 1955 352 cuts out under load. Sometimes I can blow up hills at 70 mph with all the power in the world, and other times I cannot hold 40 mph on a level. It's getting worse, too. It actually stalled in traffic last week and refused to restart. All it would do was cough and spit on the starter, but it would not catch and run. I let it cool down for an hour with the hood open, primed the carburetor with a bottle of fuel, and got it started. It ran perfectly so long as I kept my speed down: I had to limp home at 40 mph like there was an egg under the throttle pedal or else it would cut out. I thought it was vapor lock, but it was only 60 degrees outside!!! I have never in my life seen a car vapor lock in weather that cool.

- I rebuilt the carburetor and distributor before I ever drove this car outside of my driveway for the first time.

- I've tried three different mechanical fuel pumps with no effect.

- The fuel line from the fuel pump to the fuel filter on the carburetor is routed away from heat sources and the fuel filter has been perfectly clean this entire time.

- The gas cap vents properly.

- I replaced the ignition coil and it made no difference. I even removed the RFI suppression capacitor attached to the coil in case it was causing a short, and there was no change.

- I blew back through the fuel line to the fuel tank from the fuel pump end with 90 psi shop air and got plenty of air flow through it, so I don't think the line was restricted. If it was, I blew the restriction back into the tank. Again, the fuel filter has remained perfectly clean this entire time, so I do not think my gas tank is filled with rust or sediment. HOWEVER: I have not driven the car since I blew back through the line to know if it fixed my problem.


I am starting to suspect the following:

- The new ignition condenser is breaking down when it gets hot and is causing a misfire. Defective made in China parts are a thing...

- Possible breaks or shorts in the primary ignition wires. The vacuum advance flexes them as it operates, and I've seen that cause freaky problems on other cars.

- Low voltage at the ignition coil, potentially caused by a faulty ignition switch, ballast resistor, or connection. Possibly a poor distributor ground. I have not done any voltage drop checks yet.

- Potential pinhole air leaks in the fuel pickup tube in the gas tank. It seems like all my problems have happened when the tank was less than half full, but I cannot be sure about that. I have not tested for it. This possibility is my 100% absolute worst fear because it is the hardest and most expensive thing to fix. I REALLY hope this is not my problem!!!

- Pinhole air leaks in the main fuel line between the tank and the pump, or the line might be routed too close to the exhaust.

Does this all sound about right to you?

Not sure how much help I can be, but what kind of fuel are you running, and how long does it generally sit in the tank? Ethanol fuel loves to fuck up carbs, it attracts water and it separates while sitting.

I'd vote for the pinhole leak somewhere in the fuel line between tank and fuel pump. The tiniest hole that won't even show up as a damp spot will cause starvation under load. That logic includes the flex hose between the steel line and the pump ,also the flared fitting where the steel line goes into the tank. After having fought similar battles too many times most every car that comes through here for waking up after a long sleep gets a new fuel line.

V8 Packards are not prone to vapor lock as a rule.

Personally I haven't heard of capacitors/condensers not working when hot but resuming working when cold. Generally the life will be shortened by hot working temperatures (above their rating, not something your should have to worry about for purpose-built automotive ones), but not "stop and restart". Personally I doubt this would be the problem.

Next time it makes sense to, I would run through the electrical tests you have suggested for your own piece of mind if anything.

Next time it doesn't want to start for no apparent reason, immediately switch to a bottle, starter fluid, or hook up a boat tank to the carb. If it runs nice off of that, it's almost certainly a fuel problem. If not, not.

Nice thing about V-8 engines is that if one cylinder is unhappy you have 7 more. So you can more-or-less completely ignore for now anything that is cylinder-specific, like the plug wires off the distributor.

For the poor power feed to the coil question make up a jumper wire and hook it directly from the battery to the coil the same way as a car thief.

Junk ignition parts are certainly a possibility as the cool down indicates but look for a possible short circuit as well. That can be checked with a test light. If it doesn't flash while cranking there is a short in the distributor or junk parts.

For fuel starvation pull a plug after cranking and no start.

When you say - rebuilt distributor - does that mean it was sent to a rebuilder who put it on a SUN distributor machine? They are out there.

If those systems check out, do a compression test. The rings may be sticking.

Intermittent issues because of the distributor flex wire is a known issue. Usually happens when the old fabric insulation rots and a chunk falls off the wire. When the advance plate moves the wire can short. If enough insulation falls off it often changes to a direct short and no spark at all. This has become a problem for several when they try to start the car after doing work in the distributor that moves the wire.

Gas tank pinholes are another known issue as is moving debris in the tank that sometimes blocks the inlet opening. For pinholes, there are two bends in the fuel line often exposed to air where this is known to happen. If you can pin it down to a specific fuel level all the more possible. The flex fuel hose between the steel line and fuel pump is another place to check. If the hose is old and hard the inner lining could be cracked letting a chunk pull out under suction and partially block the bore.

Here is a photo of the inner tank that Ross posted some years ago. Notes show where pinholes have been found.

Attach file:

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  51-6 inside pinhole locations copy.jpg (131.21 KB)

Seems to me like an easy diagnostic test for the fuel pickup tube is to see how the car runs with a low tank of fuel and see how it runs with a full tank of fuel. Air bubbles in the glass fuel filter might also signify a problem.

I think I fixed it.

Either the rubbing block had worn down or the adjustment slipped, but by one way or another the ignition point gap had closed up significantly in just 400 miles. I reset it and now it runs fine.

That's weird. I lubricated the point cam. It should not have worn down the rubbing block that fast. I don't really like the whole locking screw method of setting these points. I might put a Pertronix unit in there if this will be an ongoing problem.

I have Pertronix in my 1954 Patrician and in several of my ‘60s cars and have never had any problem. Even when I used to take my cars in for underside and engine steam cleaning, the shop doing it was always surprised that they started right up when newer cars often had problems due to the moisture getting inside the distributor from the pressure!

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Based on questions and comments in various forums, 12v Pertronix units are quite reliable and seem to work well with very few complaints. I believe you could attribute that to the fact that since the solid state logic used in the module needs a very stable voltage supply, when 12v is dropped down to the required level there is a lot of forgiveness for underlying voltage issues because you are starting with a much higher voltage supply than needed.

6v units are hit or miss. It seems that if the overall car is maintained and reported to run well and is quick to start then logically it must be that the car and particularly the 6v electrical system is kept in good condition. There is probably very little voltage drop to contend with and complaints on those Pertronix conversions seem to be few. If that is the case, it would also stand to reason that cars with varied reports of starting, running or driving issues might also have less well maintained electrical systems. When a Pertronix is put on those cars in trying to solve other issues they seem to have a fair number of complaint and failures to the point many of them are soon reverted back to points. Suspect voltage drop thru poor connections is a big part of those issues when you do not have much extra to start with.