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

Avoid aluminum head. Even with modern corrosion inhibitors, Red Line Water Water or No-Rosion, they are trouble. What's ridiculous are the guys who then polish aluminum heads until they gleam, which reduces surface area and cooling efficacy.

As described, Packard already suggested what owners wanting a trace more oomph could do. Skip the cowboy crap, don't reinvent the wheel. Get the engine right, "factory standard."

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They are like hens teeth. I asked about the compression ratio they provided as another data point as to what was run on the 356 in the past. Although the head looks flashy having dissimilar metals with different expansion rates joined together increases the chances of seal/gasket failures as well.

Anybody know what the CR was for these heads? I've not yet seen evidence that there were different Edmunds Packard heads for the 288/327/356/359 8 engines, just one. If so, that would give different CR for the different engines which doesn't make much sense. Anybody have information, or know what CR one got with it on the 356?

I have found some iron heads from 22nd series and later -- at least three 288 heads, a 327 and a 356, plus one mystery HC head with no displacement indication. I assume HC is high compression, but oddly the combustion chamber is much deeper on this head. It also doesn't have the flat center ridge running front to back. Anybody have info on what this HC head is intended for?




Also, any way to distinguish a 327MT vs. 327AT head?

I think if you're trying to get a little more HP, this should do the trick.

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Drop a Cybertruck drivetrain in it

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No need for a higher compression head with that big air pump on it. I don't think that will be much help with fuel economy.

I pulled the 356 head and did some comparative volume measurements of the combustion chambers. The 356 measures 95cc, the 327 head is 90cc, and the HC head is 120cc. Very little difference between the 356 and 327. Why the supposedly HC head is so huge is a mystery. With that head I think the compression would be too low for the gasoline to even combust -- the engine would not start. The plan is to install the 327 head but with such a small difference I'm tempted to check volume on a 288 head to see how it compares. I'm wondering if the 356 head has already been planed at some point in it's life. If one does the math assuming the 356 head is stock, there's a 5% difference in volume so a CR of 6.85 would become 7.21, not the 7.53 per the chart.

However, as it seems whenever something is torn into other issues arise and this time is no different. Head removal revealed a problem with cylinder #4. The rest all look just fine and the head gasket appeared fine with no indication of leakage anywhere. There is oddly some severe metal erosion on the intake valve head and on the block between the cylinder bore and exhaust valve. Picture attached. The seat on the intake looks okay still, but the seat on the exhaust looks compromised -- not severely but I assume there's some leakage.

Any ideas how this could happen on just #4?

PRH's are very common, I have encountered many of them in my 53 Cavalier. (Packard Rabbit Holes) Sometimes there's a hole within a hole within a hole, and not unlike the movie Inception, you get in so deep that it's hard to remember where you even started.

When I bought my 53 Cavalier it was not running and had been parked for years, maybe decades. After I got it running it had a tapping sound, not a knock and not a tick. I tried all sorts of things to see if it would go away, but ended up opening the engine, which lead to 8 rabbit holes!

Anyway, I too found that #4 also had the worse valves, in fact I'm 99% sure that my tapping sound was an extremely worn exhaust valve guide on #4.

As far as why, I don't know. Maybe #4 runs richer and hotter?

If you pull your valves, I would check the clearance on the guides.

If you happen to find any of the rabbits making all these holes, KILL THEM!!!

I'd guess that at some time or other, the head gasket on that cylinder leaked, or the engine got water in that cylinder from some other cause. Chronic detonation can cause erosion of metal surfaces, but this would usually show up in damage to the piston.
An intake manifold leak can lead to burned valves in specific cylinders due to running too lean. A problem with the water distribution tube in the block could lead to valve problems in a particular cylinder, and so could improper valve adjustment or a a stuck manifold heat valve.

Heads with larger combustion chamber volume are probably for higher displacement engines. As I understand it, a number of Packard heads will interchange among different displacement engines.