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Took our 29 out for a local region AACA tour Sunday in cool to late day warm temps. Route was a mix of rural and urban roads. Did fine until I got behind one of those ten minute traffic lights and had to wait thru two changes. Started out and vapor locked going up next hill. Fortunately next stop was just over the hill and made it choke etc. Let her cool off under a shade tree with the hood up while we were there for about a hour and half and ran fine all the way home, about 38 miles. Have since aquired exhaust wrap and done the exhaust pipe and insulation tape for the gas line to carb. Spoke to an old friend who has a 27 twin six and he adds a gal of diesel to 19 gals of gas to stop his from VL. Going to do that also. Anyone else used diesel?

Jim

Great news- I'm planning to wake up my car this weekend. Three weeks ago we had 18 inches of snow on the ground. Today it was 60 degrees.

I guess you';e fighting ethanol or some horror in you fuel. Remember your car was set up for fuels that were much less volatile.

I've heard of the diesel remedy so it's not off the wall. Some people also use Marvel Mystery OIl, which might be a less extreme solution. There are ways to set up a return line to the tank to relieve the vapor pressure, you might be able to find a diagram online. Whether or not this would work with the low fuel pressure of a vacuum tank system is an question for someone else to tackle

Regards


John Harley

I tried it once in preparation for a long, hot July 4th parade in my 34 Packard. That car has never had vapor lock before and didn't have it that day with about 2 gals of diesel in 20+ gallons of gas. But it sure smoked like a dirty diesel bus and fouled the plugs a bit. So my experience doesn't help you address how well it might help with vapor lock, just that other than a lot of smoke there were no real negative affects.

Has your vacuum tank been serviced recently?

Nice to hear of another 6th series on the road.

We've had our 29 many times during the SoCal summer days when it's well over 100? plus out here and never had vapor lock. I would first try checking the exhaust wrap and as stated earlier, the vacuum tank. I truly see no need to run MMM or any additive in these engine unless you are putting a few hundred miles a week on them. The other thing is your coil may be over heating causing loss of spark until it cools. I had that issue on an old Dodge Charger I had years ago. It would run for a while and just plain die until it cooled off. Played hell trying to figure out what it was. I have a spare vacuum tank here but I am not sure what it is worth or if it is any good. Next time it dies on you and this may sound odd, hopefully it will, check for spark. At least it gives you a chance to actually diagnose and eliminate trouble spots.

Jim, I have had a 1929 Packard on the road for about 6 years now and a 1922 for over 20 years. Both cars vaporise badly in hot weather especially on a long climb or in heavy stop start traffic. I have tried adding diesel but found adding kerosene works much better. I have added up to 20% on a very hot day and found no change in performance in fact I suspect it would run fine on 100% once the engine is hot. The other modification that I believe is essential is a heat shield under and around the vac tank. I have also insulated the exhaust. However despite all of this the car will still vaporise under the conditions you describe if the day is very hot say 100 deg +.
The final solution that I am yet to try is to fit an electric fuel pump that feeds directly into the carburetor. Feeding it into the vac tank is futile because that is where most of the heating of the fuel takes place. I have spoken to other Packard owners who report that this completely eliminates the problem.
As a matter of interest I have discussed this with a representative of a major fuel company. The reason why the problem is worse now that when the cars were new is that modern fuel has a much lower boiling point today. It is fine in a modern car with a high pressure fuel injection system as increasing the supply pressure dramatically reduces the boiling point. When it first happened on my 1922 on its first run many years ago I thought it was fuel blockage so after checking the main jet in the carby I then removed the top of the vac tank and even though the car had been stopped for some time the fuel was still bubbling away in the tank due to the heat from the exhaust manifold. I had some heavy gasket material with me which I crudely wired under the vac tank to shield it from exhaust heat and was able to drive on without further problems, (it was only a mild day).
David - Australia

Thanks to all for their comments. Have had the same problem with my 32 Ford with stock 34 85HP v8. I fixed it with a elec pump under the frame and only have to hit it when the dreaded VP surfaces. As stated earler, have wraped exhaust header, sediment bowl and gas line to carb. Am going to fab a metal baffle between the Univac and exhaust manifold and do the keros. thing on our next long run coming up in May. I can remember even with real gas having VP problems on a 49 Olds back in the late fifties. With what we have now, more drastic measures must be taken.