Packard Forum Index » Post-War (1946-54)

Hello Packard Friends and Greetings from the Last Frontier,
Here's the problem with my '47 Custom Super (356) that I am awakening after about a 10 year slumber.

She absolutely will not start when the temperature gauge is anywhere near or above warm (even with electric fuel pump on). When cold, she will start within 5 seconds or so of starter engaging, and pedal all the way down (as she was designed to do). An immediate restart after highway speeds is not a problem, but once she gets warm/hot as from extended idle or city driving, only a 20 minute cool down will get her going again. Note that 75 degrees is a warm day here, so extreme ambient temps should not be an issue, and she has never overheated on me. Cooling system seems perfect.

Things done so far by reputable restoration shop or me, include the following:

1. Carburetor rebuilt and sticking accelerator pump fixed.
2. Full tune-up (new plugs, points adjusted, new condenser(me), timing set, carb adjusted).
3. New coil, new rotor(me).
4. Rebuilt mechanical fuel pump installed (me). Auxiliary electric fuel pump has been installed, in-line fuel filter replaced with new. Inside of gas tank inspected and looked clean.
5. Heat shields on fuel pump and carb are in place.
6. New, strong battery.

As the starter switch is under the accelerator pedal, my resto shop added an extra starter button under the dash in case of flooding. Use of this switch with or without some pumping of accelerator doesn't help - engine just turns over but does not catch.

Rather than launch willy-nilly with ignition wires(look good), voltage regulator, distributor work or other stuff, I would appreciate suggestions on how to diagnose and proceed in a logical fashion to achieve reliable re-starts.
Thanks in advance,
Mark

Oh, by the way, she runs well after she starts. I get some very small amount of black soot and water right after she starts. Compression test results were OK.


She seems to stumble and run a bit rough when the OD is engaged and I think that is a separate, secondary issue.

I would check the timing. Make sure it is not too advanced.

First things I'd do is to check the adjustment of the carburetor anti-percolator valves and the float/fuel level. If everything checks out OK there I'd check the fuel pump pressure. I assume the carburetor insulator block is in place.

Mark, I agree with Harry and even though you have set the timing I would at least see if the following eliiminates the problem or has an affect on it. First scribe a mark on the distributor base and line it up with a consecutive mark on the engine block. Once you run the car up to the temperature where it gets hard to start, loosen the distributor just enough to allow it to rotate a little each way. Rotate it while someone is attempting to crank the car to see if it starts with the distributor in a different position. If that doesn't work, line up the marks and tighten the distributor back down. From there I would open the throttle by hand while looking down the carb throat to make sure that the accelerator pump is pumping fuel. If it is then cup your hand over the carb throat while someone attempts to crank the car and see if it starts using that procedure. It sounds like you've replaced or rebuilt all of the critical components and checked the most likely causes but how about vacuum? Have you hooked a gauge up and checked it?

If gas issues are ruled out, one other thing might be measure the voltage across battery sitting and then while cranking. Then measure at battery solenoid connection and at coil terminal (I know that one will be hard with the 47 configuration) to ground both sitting and while the starter is turning over. When hot in particular but maybe both engine cold and hot to see if any difference.

6 volt systems are unforgiving of poor grounds, too small a battery, a wire, or connections in general. If the hot engine is causing enough load or the starter or battery has dropped in efficiency, the starter will need to pull extra current. The least little resistance and there may not be enough left at coil to provide a strong spark. I would expect the solenoid terminal to drop to maybe 5 under load and if coil is much lower than that, it may not have a spark that can jump the plug gaps.

I think even with the new loom, the pertinent wiring and some of the grounds will still be old.

When the problem occurs is there any indication of gas leaking around the carb or area of the carb??????

I am not familiar with this particular carb. But What u describe is most likely the anit-perc valve or SOMEKIND of a carb bowl VENT that is restricted plugged or not working. Since u had accelerator pump problem after rebuild then most likely it is anti-perc valve out of adjustment. ON SOME (which means not all) carbs the anti-perc valve is linked to the accelerator pump. THerefore, if changes made to accelerator pump then anti-perc valve may need adjustemnt/readjustement.

Find out if the anti-perc valve IS or is NOT linked to the accelerator pump. Check adjustment of perc-valve either way.

All of you guys are great and all of your suggestions seem like rational possibilities. I really appreciate the way different areas of expertise come into play on this site to help those of us who are not so mechanically inclined, but still love driving Packards.

Packard V8/Owen - the insulator block is there, I think, but I will double check, and I do notice some gas at the base of the carb. Probably going to the carb eventually.

Howard - The replacement battery was slightly tailer than the old one but had higher cranking amps. I had to replace the ground cable from a braided wire style to an insulated cable - I will see if I can find a longer braided style to fit and also do the test procedures you suggest. Thanks for remembering that I had the new wiring installed.

Gator/Harrybar - timing/vacuum are easy checks to make -thanks.

Thanks guys - I will keep you posted on how things go. Happy Independence Day to All,
Mark

Enjoy your holiday tomorrow as well. And check those anti-percolator valves first - your symptoms are a classic.

PS - make sure your manifold heat control valve, if not functioning, is atleast stuck in the open position.

Hi Owen,
The P-Valves will probably be the start. Problem is, I am not familiar with them. I assume they are inside the carb, but can you describe what I am looking for and then, what is the adjustment procedure? Or, can you point me to some reference - I come up with nothing in the Service Manual.
Thanks!!