Packard Forum Index » Modification Discussion

Whew, that's gonna be some honker. Since you live in the land of Autobahn, you might look for a differential out of a non-overdrive Packard to give you longer legs in overdrive.

Old rule of thumb was that, in general, an ohv engine can go a full number higher compression than a flathead without pinging. I agree with the gents above, 9.2 sounds high as a kite, and the above adviso to doublecheck valve clearance is good.
You have to think Packard knew what they were doing when they called it a day at 8.7 to 1. Perhaps you'll make it.
Please keep us posted. 327's are good, husky engines.

We stuck a 327 head on my '47's 356.
Since the 327 came out halfway through the '47 model year so Packard could finally offer a postwar convertible, that model of the '48 bathtub coming out earlier, a 1947 Packard Service Counsellor mentioned using the 327 head on the 356 would give a little more power.

Tho' Packard never wrote anything about using the 288 head on a 356, a friend did so on his '42 160 convertible.
But we figure i'm still a relatively conservative 7.5:1 and he around 8:1.

I wonder if carbon is an issue with modern oils, cleaner gasoline, than when your engine was new or late model.

carbon deposits shouldn't be a problem using modern fluids and the lack of led in the gas. and quite possibly running the highed compression with the increased heat that goes along with it may even help keep carbon deposits out of the chamber.

I've decided to use the original 327 head, so I should be at 8.1:1 CR. That should be nice and safe.
The car was originally a three speed non OD, so it already has the 3.90 rear axle ratio. Not like I want to make land speed records, but cruising at 60mph or so will be comfortable. That is pretty much the minimum speed on the autobahn, and even the back road traffic moves at 100kmh(62mph). -I have other vehicles when I want to go fast
My engine builder keeps getting 'urgent projects' to do and delaying my build....it's getting frustrating.

I think you will be far happier with the lower compression. In overdrive you will be able to effortlessly maintain 125/130 all day long--but with a rate of consumption that will make you cry. These cars are amazingly un-aerodynamic.

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I just drove a '54 Clipper with 327 "Thunderbolt" 3-speed OD. Don't know the axle ratio, but the car practically refused to go below 60 mph on the speedo. 70 was "comfortable" and it had a lot more beyond that. You should be able to bite a few BMWs in the ass!

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I'd like to learn more about installing the 288/327 head on a 356. Are the head gaskets the same for all three, too? Which would you use, if not? Any chance of finding that Service Counselor date? Does anything else need to be done before attaching the different head?

The same head gasket was used for all 356 Engines and 1948-52 288 and 327. The part number for 1953-54 is different but I don't know why as the bolt pattern was still the same.

The later 288 and 327 heads will drop right on to any 356 but there may be differences in mounting of throttle linkages and the temperature gauge connections are different for 1948 and later.

Service counselor Vol. 24 No. 7 has the article on changing compression ratio.

Water outlet size is the same but the long stud used for the 356 would have to be used in order to retain the cast outlet neck.

Thank you very much for that.

The question begs to be asked: Since the 327 head fits the 356, and the 288 head fits the 327, why did Packard not recommend putting the 288 head on the 356????

One pure guess on that was with a stock 6 volt ignition and very low octane gas it might get into detonation. Again that's a pure guess but 6V ignitions are not known for there great ability to ignite.

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Really? This is news to me. One of the reasons to go to 12-volts was for cranking the ever increasing compression on the new OHV V-8s, but never heard it was for hotter spark.

(o[]o)