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

Thought I'd try you guys on this. The engine starts and idles well. I get her on the road and will cruise around for 15-20 minutes and it drives like a dream, then if I run her up to 55, the power will just die off and 35 is all I can do in 3rd gear without backfiring repeatedly. The engine runs a little rough at idle then, but pull the throttle and BANG!. If I shift to 2nd and just release the clutch it will backfire like a banshee. I limp back home with a bunch of pissed off people behind me then the next morning I can do the whole process of good-bad-worse again. What I've done is:

New plugs .025 gap
New Packard 440 wires
New Distributor cap
Took wires out of the metal guide

Another question I have is shouldn't the sed bulb be full? Mine is never full and usually has only a dribble of fuel in it. Seems that for a sed buld to collect sed & water it should always be full.

Thanks

Was the car running OK before you changed the plugs etc.? If not then I suspect that it may be a coil going bad when warmed up. It could also be a short or open circuit in the primary ignition wire which could cause intermittent coil failure but why when only warm? A bad condensor will also cause a backfire so possible change that also.
Another cause of a backfire could be fuel starvation but since the problem occurs after the engine is warm I suspect the coil. The sediment bowl should be full or at least almost full at all times so a check of fuel pump pressure is in order or the filter element might be plugged or there is something in the gas tank or line restricting flow. I amsure others will chime in with other ideas.

U replaced some parts. Did the car act that way BEFORE u replaced the parts?????

If th car ran fine before u did the tune up then most likely it's plug problem. What kind of plugs are in there now and what was in there BEFORE????

I vote for the condensor (having lived through similar symptons in the past), followed by the coil. Condensors are cheaper than coils so I usually start there. Fuel starvation causes through-the-carb backfires. Ignition problems --usually--give through the exhaust backfires.

Thanks guys, it was worse before the "tune up". In the dark there was light dancing all over the wires and cap. The coil is probably 10-yrs old, condenser as well. I looked at some coils on line and most appear rebuilt. Are there any new coils being made by anybody? Also what is the armored cable coming out the back of the coil?

I'll get the condenser and try that first. Is there a compatible condenser that AutoZone/Advanced/NAPA would have in stock?

I never gave the sed bulb much thought till I went to an antique tractor show and every engine had a nice full bulb.

The wire out of the back of the coil is neg connection which goes to the ignition. The coil is a transformer that needs AC voltage to work. Finding a new coil with the connection on the back is expensive $100-300. Generic 6v coils can be found at old time auto parts web site(or something like that) for about $12. You have to run a wire from the front of the coil to the rear connection.

Is there a compatible condenser that AutoZone/Advanced/NAPA would have in stock?

Application-specific condensors for these old cars have been long gone, just ask for a "universal" 6 volt condensor, just get one with a long-enough lead to reach the connection point.

Typical value for ignition condenser is .22ufd or microfarads.

You should be able to pick one up at an electronics shop.The new ones are a lot more durable than the old wax paper and tinfoil jobs. Should last the life of the car.

Dear KA, I have the same problem with my sediment bowl. If I let my car sit for longer than, say 5-6 hours, I have to "bleed" it in order for the bowl to fill. I have an electric pump on mine so this is fairly easy. I turn on the pump and loosen the nut on the bottom of the bowl a bit until the bowl fills. Tighten it back up and off I go!

Great Info! Bought the correct coil off ebay $131 includes shipping, and a 6 v elec fuel pump ran about $60 with the shipping. I'll find the condenser Monday then start to dig in. thanks again gentlemen!!!!!!!!!!!