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1949-50 8 cy Packard

I have a 1949-50 8 Cy Packard from the Packard Motor Co Of Boston . It had been maintained at The Waldo Garage , 10 Waldo St , Brookline, Ma. There are 56,000 miles on it and it burns clean . It has an ultramatic transmission . Is there any way I can make some adjustments and not run high test gasoline in it .

Isn’t this the one with the flat head 8? Why do you run premium? If it knocks, then the timing needs to be retarded slightly. I can’t imagine the engine requires premium, unless there’s a lot of carbon buildup. That could be fixed fairly easily by pulling the head and scraping it out, an easy thing to do with a flathead (comparitively speaking, of course).

Also, why do you say ‘Boston’? Packards weren’t made in Boston.

It sounds like you have a really cool car, one that should be given only the best of care. With 56K miles you are not driving it very much, so why worry about a few extra dollars a year for premium?

If the motor has high compression, 10 to 1, and calls for premium it is best to stick with it. If the motor has low compression say 8 to 1 then you may be using premium without needing it. Premium back in the early 50’s may have been lower octane than today.

If the motor “knocks and pings” on regular you can retard the timing a bit, but why detune a motor that is running well?

If the Waldo people know the car well, stick with what they recommend.

Good point, why worry with so little use? But this has (as best I can tell) a 7:1 compression ratio, so if it’s knocking, something else might be wrong.

In the days that your Packard was manufactured, gasoline contained tetraethyl lead compound to raise the octane. This compound is no longer used. Octane rating today is an average of the resarch method and the motor method. The actual octane probably hasn’t changed much. I would guess that the compression ratio of your Packard is low enough to allow the use of regular.

I owned a 1954 Buick Special with a V-8 and manual shift. The owner’s manual allowed the use of regular fuel in this car. The compression ratio was 7.2:1. However, the other Buicks, including the Special with Dynaflow automatic were supposed to be fed premium. On the other hand, the Chrysler products with the hemispherical V-8 could run on regular. You might try a tank of regular and see if you get a spark knock. If you don’t, regular gasoline is o.k.

I agree with Texases that this car likely has a significant build-up of carbon in the cylinders, thus necessitating the use of premium gas where regular would normally suffice.

Carbon build-up was a problem with all of the old flat-head engines, so much so that most people would have the head taken off for decarbonizing after 30k-50k. On a 60 year old flat-head engine with 56k on the odometer, it would not be at all surprising that this car needs to have the head removed for decarbonizing.

I suspect that the “Packard Motor Company of Boston” was the dealership from which the car was originally bought, as Packards were manufactured in Detroit. Since your car has the Ultramatic transmission, it could only be a 1949 model if it is a Custom Eight model. If it is any model other than a Custom Eight, then it has to be a 1950 Packard, because the Ultramatic was not offered on models other than the Custom Eight until 1950.

On the Vin Plate , it states " delivered by Packard Motor Company of Boston 10/18/49. There may have only been one dealer and it closed in 1949 I believe . This is the straight 8 356 CI . Over the years I learned if I put in high test the knocking would stop . I will try retarding the timing . Thanks Bryce

Well, I’d recommend having the carbon cleaned out, like VDC said. You may not like how it drives with the timing retarded.

I used to use Casite Motor Tune-up in the cars I owned that were made before fuel injection. I would remove the air cleaner and pour it directly down the carburetor while the engine was running. I would pull on the accelerator to boost the engine speed. I would also add a can of Casite to the gas tank. After I drove the car around for a while, I would then take it out on a highway and run it up to a pretty good speed in second gear. The black smoke would pour out of the exhaust pipe for a minute and then clear up. This would always make the car run better. A family friend bought a 1949 Packard at an auction while on a trip in the mid 1950’s. He and his family were about 1000 miles from home and the intent was to sell the car for more than he paid for it. At any rate, on the way back, he was driving the Packard and his wife was following in the other car. He started to pass another car and floored the accelerator which kicked the Packard out of overdrive. The black smoke poured out of the exhaust so heavily that his wife thought he had ruined the car. What happened was that the carbon loosened up and then the Packard, which had seemed sluggish ran like a scalded dog. His wife liked this Packard so well that they sold their other car instead.

Whatever fuel you use, make certain it contains no ethenol. The fuel system in this vehicle was never designed to tolerate any amount of ethanol, and can result in damage to the elastimer components in the fuel system.

Here in Minnesota, The Minnesota Street Rod Association provides a list of gas stations that sell non-oxyenated gasoline for those who have older vehicles who’s fuel systems would be damaged from the ethanol.


If he did pull the heads and removed the carbon, with today’s no lead gas the motor should not build up carbon ever again. Is this correct?

No. Gasoline is a hydrocarbon. Carbon deposits form when gasoline comes in contact with a hot component such as the backside of an intake valve, and vaporizes leaving carbon deposits.


The low compression ratios of the old flat-heads made them very prone to carbon build-up. And, of course, those old ignition systems didn’t help either. No matter what fuel is used, this design will inevitably build up carbon in the area of the heads.

Yes, and when you think of the wide, flat combustion chamber, there are plenty of places for the carbon to collect where the gas doesn’t get well burnt.

This car is a custom Eight . It is called 1949-50 because in 1949 it did not sell and was re-Vin numbered as a 1950 . The original was found on the MFG information sheet located on to of the glove compartment and on top of the fuel tank . I don’t think the Waldo Garage is still there . Their Tel # is LO 6579 according to the oil sticker on the door jam . From the rest of the replies I will start with the carbon build up first . Thanks Bryce

You’ll want to get hooked into the thriving Packard restoration community. There may be a club near you, and there’s lots of info on the web. That engine was made for years, so you shouldn’t have too much trouble finding parts for it. Buy a Hemmings Motor News, you’ll find lots of info and listings.

In the days that your Packard was manufactured, gasoline contained tetraethyl lead compound to raise the octane.

How gasoline gets/got its octane rating isn’t the point. What was considered “premium” then might be considered “mid-range” now (or vice-versa). I agree that the engine is probably all carboned up (effectively raising the compression ratio) and that needs to be addressed.

Something else to keep in mind: the valve seats were made to depend on the lead, and will be damaged by running lead-free gas. You might want to look into whether you can get hardened valve seats installed when and if the head is pulled off for decarbonizing. Otherwise, you might want to use a lead substitute additive.

Finally, 60 year old rubber and other elastomers used in the fuel system are probably close to failure anyway, from age. Using pure gas might prolong their life a bit, as compared to running E10, but you’d never want to run anything above E10.

Tom and Ray have suggested a couple of times getting a spray bottle of water and spraying it into the carb to decarbonize an engine. “You will be amazed how much water you can spray in there!”

If you’ve ever removed the head from an engine with a blown head gasket you’ve seen how the resulting coolant leak into the cylinder(s) cleans the piston(s) and combustion chamber(s). You can accomplish pretty much the same thing by SLOWLY dribbling or squirting water into a carburetor or throttle body. You can’t pour it in quickly, obviously, without stalling the engine, but much worse: you can hydraulic the motor and destroy it if you fill a cylinder with uncompressable liquid while it’s running.

“you can hydraulic the motor and destroy it if you fill a cylinder with uncompressable liquid while it’s running”

I think that you meant to tell us that this can hydro-lock the engine, which is just a bit different from “hydraulic”.