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I remember reading that the packard engines had acorn nuts throuhg 1939. I am about to paint the engine but would like to know if this engine originally had Chrome Acorn nuts and washers. The as recieved car had regular nuts. The engine was manufactured mid model year. The engine has probably had several valve jobs over the years (83000 Miles)so the Acorn nuts may well have been replaced

I have Acorn nuts and washers. to be authentic, Should I install them?

Actually, they were nickel-plated, not chromium. Install acorn cylinder head nuts if you like their appearance, they are legitimate but were not standard equipment. But I'd recommend against buying the chrome-plated ones that are on the market and instead go for the stainless steel ones, they have an appearance much closer to nickel plate.

Watch your torque if you go to SS. Spec for a SS 7/16 is around 34 ft lbs. Im sure theres a saftey factor in their calculations so figure you can get away with 40 lbs.

40 lb-ft will never hold a head gasket. I've installed lots of SS cylinder head acorn nuts on Packards, I usually buy them from Tioga Stainless - not sure of which stainless alloy they use but I always torque them to 62 lb-ft and never ever had a problem. I have however had serious problems with the chrome-plated ones that I bought from a CCCA region, they were of very poor quality and stripped easily.

I believe the lower torque values are for Stainless bolts to stainless nuts. Stainless does gave a tendency for galling. I had planned to use a final value on the third torquing of 60 lbft of torque for the stainless nuts on the steel Studs. Any bad experiences doing this? Any comments?

Also important is the class of the nut, what Grade it is. Tightening torque for a Grade 2 fastener is much lower than a Grade 8.

I've always used 63 ft-lbs. as the torque for head nuts. Anything less and you're going to have problems with leakage.

Torque them per the specified pattern, circular CC'wise starting from the center of the head.

Torque in three steps, 20, 40 and 63 ft-lbs.

Re-check the torque again after 100 miles, following the same torque pattern originally.

Cast iron head torque is re-checked hot, aluminum head torque is re-checked cold.

Also a good idea to use new high strength studs. Each 7/16" stud in the head is clamping down with around 10,000 lbs. of force. You want to put the stud in tension, but not so much that it yields and doesn't keep the clamp force.

To high of a torque, a low quality (strength) stud, or low quality nut will yield.

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Good advice from 32Model901. In the day, part of a complete tune up was checking head and manifold torque.