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I'm sure you're right. I haven't had a Packard engine apart yet to see how it works, or seen anything beyond pictures, and my own in a dark storage building. I saw pictures of the valvetrain from the side and assumed they were lifters actuating rockers like 'regular' engines.

I've only rebuilt a 302 Ford engine, a '67 Triumph straight six, a 2.0L Dodge Neon DOHC, a 1.6L Mercury Capri DOHC, and a few 13B Rotaries (which don't have any valves at all), so all of my engine advice should definitely be taken generally, not empirically. :)

It may be too late but.. you can remove carbon from the head with a steel scraper but for the pistons use a BRASS scraper, they are aluminum and a steel scraper can scratch or gouge them.

A wire brush in a drill will polish away the last of the carbon. Just go easy on the pistons.

If you install new rings you should scrape the carbon out of the bottom of the ring groove. Take a piece of an old ring, grind to a point, stick it in a file handle and you have a ring scraper. Or, you can buy a special tool.

This cylinder head question comes up over and over so I did a little research in the inventory:

I wandered through the magic basement and measured every cylinder head I could find that I was reasonably sure had never been milled. They ALL measured 1.781" thick, or if you prefer 1/32 over 1 3/4. These were all 48-54. So that seems to be the stock thickness. The 359 heads are another matter, and I didn't have any to measure.

Further, it turns out there is an easy way to tell if they have been milled. All the untouched heads showed broach marks; that is they were not cut flat with a rotary cutter, but were rather dragged under a highly glorified file to flatten them. This can be seen by the longitudinal scratches from this process. If milled, you will probably see circular marks.

And about milling heads to "true them up". I only do it if there is erosion or other damage. These heads are actually quite flexible. I supported a head by its ends on my Bridgeport's table and placed an indicator in the middle. I can flex the head .002 with my fingers. Those 38 nuts are going to pull out any reasonable amount of warpage.

Thank you Ross for the median head thickness' found and the "flexibility" information of the heads. I've added your post to my library 'cause one of these days I'm going to need to remove the head from one or both of my Packard's.

I am pleased to read about cylinder head thickness measurements Ross did. I had thought about this a while back and may have even posted my thoughts. These numbers are valuable to anyone with an engine in the 48-54 years (except 359). Also, the advice Ross give about milling the head only if it has erosion or other damage is good. Check the thickness and finish first. Thanks, Ross.

(o{}o)

Ross' information is (as always) useful and perhaps needs some emphasis. It's been said on here perhaps 100 times, DO NOT surface plane or grind a cylinder head unless it's absolutely necessary - and check for valve clearance before and after. There are a lot of cylinder heads around with no use other than for a boat anchor, and the supply isn't infinite and dwindling.