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

Hi I have a hot start problem too I have a 52 200 ,I didnt know tha carb had an antipercolation valve ,is it something that can be checked externally or is it a take down?The phenolic board sounds smart anyone know where to get one thats made already? I noted some insulation around the fuel line on one of the shots on the thread ,that seems like a great idea ,its original looking .my heat shield is in place but I was thinking of epoxying some reflective material unobtrusivly under it .What is the jury on the gallon of diesel in the tank to make up for the alcohol ?

On my '54 there is a ~1/2" thick phenolic insulator between the manifold and the carb. This help to insulate the carb from the manifold heat. I often see these missing on cars. The insulator looks like a black "plastic" spacer and is the exact shape of the carb gasket.

As other said the electric should be back by the tank as it's more efficient as a pusher, than a puller. Not sure what type of electric pump you have, but if you want to start using the mechanical pump again, and then only use the electric as a primer or as a booster in vapor lock situation, they I recommend that you make sure the pump is can "drawn thru" when off.

Also make sure to have a fuel filter between the tank and the pump as nothing destroys an electric pump quicker then debris.

Great discussion. Keep the information coming. I too have had the same problems with my 51. Dying at low speeds after leaving a stop light and not being able to start after it's hot. Does seem to be flooded. Very interested in the the diesel fuel and the anti-percolation valve checks and adjustments.

I think if I ever get this engine back together and the car back on the road that the hard starting problem will still be there. Interesting thing is I didn't have any problems for the first 4 or so years I drove the car. It was my daily driver then.

I'm re posting my question regarding the addition of diesel fuel to the gas, some how it got passed over:

"What does the adding of diesel fuel to the gas do?? Is it good on an on going basis? Would a 51, and 53 Packard benefit from this as some kind of prophylactic use even though there aren't any starting issue? Inquiring minds would like to know...."

To answer your question: As I understand it, the diesel (5% mixture) keeps the ethanol laced gasoline from easily vaporizing. It does not seem to affect engine performance except to greatly reduce the tendency to vapor lock. There is no tell tale diesel smoke or smell.

I ran into a bad vapor locking situation driving my '47 Clipper Custom home from a car show earlier this year in stop and go city traffic. It was a warm day with temps in the 90s. It never completely stopped running, but it was a miserable experience keeping the engine running especially after idling at red lights. I had no more vapor locking problems after adding a gallon of diesel to a tank of gasoline in the same kind of driving conditions.

I also must point out that the car has a fuel pump heat shield, an insulating gasket between the block and pump, insulating sleeves in the pump bolt holes, and insulating washers between the bolt heads and the pump body. The car also has a heat shield and insulator between the carburetor and manifold. The car is tuned correctly, and the manifold heat control valve works freely. It does not have an electric fuel pump.

I hope this helps.

(o[]o)

What are the drawbacks of adding the diesel fuel. Are there any harmful side effects?

Interesting
I have the thunderbolt 8 in my 52 200 that likes to not start when hot mabey its a hot fuel system !

I didn't know what the bolt insulators were for when I installed the rebuilt mechanical fuel pump ,but now I do .
There was a booster electric pump installed back at the tank but I took it out because it was wired incorectly .(I saved it in the trunk sounds like if its a free flowing one I could re install it by the tank on an ignition powered switch under the dash to use in vapor lock emergencies
I dont recall exactly if there was an gasket between the fuel pump and the block,but I think it was just a gasket and not anything that seemed like an insulator gasket ,is this something you made upspecial ? seems like a good idea .
I have the heat shield installed between the pump and the intake and exhaust manifold .
Is the heat shield between the carb and the manifold you mentioned a stock item or something you made up?Shall I get out the coffee can?
The carb insulator phenolic block ,was this a stock thing I could order somewhere ,are the studs long enough to allow for it on the stock intake I wonder ?
5% deisel sounds like a harmless fix ,would be easy to keep a gallon of deisel at home to add , but how much gas is a full tank?Im bad at math so have to figure out how much to squirt in there

I don't believe your particular model used the heat shield between the carburetor and the exhaust manifold, that was mainly a feature of the "senior" 356 engines.

As to the insulating block between the carburetor and the manifold, just check the parts book to see if your model was supposed to have one.

If your model didn't have a thick spacer between the fuel pump and the engine (check the parts book to determine), adding one will change the relationship of the pump arm to the camshaft with possibly nasty results. Ditto for eliminating it when one should be present.

Again, check the parts book - most of the answers are there.

OK, the FAQ post, FUEL & EXHAUST: Stalling or Hard Starting When Hot (Vapor Lock), is now online.

Let the stone-throwing begin.

Very nice presentation BH. But again and to repeat, folks shouldnt' ignore ignition or electrical problems when evaluating hard hot-start situations.