Not a question, I was answering Packard V8. I simply use this hill as reference. If it slowed to say 35 mph then I know there is a problem, 40 mph at the top is good for this hill and this car which is a 633 sedan with a non standard 4.3 : 1 diff.

I also have a brass era veteran that struggles to hold top gear and slows to about 10 mph on thee same hill.

In answer to Packard V8 I hit the bottom of the test hill at 45 mph and the speed drops to 40mph at the top.
As Owen-Dyneto said, uniformity of compression is more important as it causes rough running.

I recently had my 1929 Packard off the road for some repairs for a few weeks. During that time I had to turn the engine over by hand so I loosened all of the spark plugs to make it easier to crank.
With work complete I took it on a test drive on our nearby "test hill" then on a 100 km club run. It ran very well, except for what sounded like the start of a failing exhaust manifold gasket.
The engine was recently fully overhauled so the manifold leak was puzzling till I recalled a few days later that I had not tightened the spark plugs.
They were all very loose, typically a couple of turns to tighten.
So I tightened them then took it back to the "test hill" expecting a noticeable improvement but it topped the hill maybe 1/2 mph faster at best. Being realistic it felt no different except the exhaust leak had gone.

So how critical is is it that valves are sealing and rings holding compression?

It reminds me of a comment recently from a friend who has been around cars all of his long life, he said that an engine reaches its peak performance when its about 75% worn out!

I guess his memory was colored by time. He wrote about a very large number of diverse cars, I certainly would not remember all those details 50 years later. We will never know whether it was in fact a 734 given the other errors, maybe it was a 740 and the other features belonged to the many other cars he owned or drove. I have never heard of a surviving 734 in Australia - pity.

At least on 734 made it down here to Australia. A local car enthusiast who owned and drove a large number of fine cars during his life, wrote of his motoring experiences in an article in a local club magazine. The story began as follows:

The best car I ever drove in its time and place was a 1931 Packard 734 Roadster. This was sports car with 134 HP engine, 320 cu ins, straight eight. It had magnificent brakes,4 speed synchro gearbox and hydraulic shock absorbers adjustable from the drivers seat, back and front. I drove it in a couple of Light Car Club trials in 1934 and 1935. You could through this big car around with ease. I followed a J2 MG which was the latest thing in sports cars and he couldn't get away from me on the twisty bits. I took him easily on the first straight. Yet it would go anywhere in top gear. Truly a wonderful car.]

I am not sure about the synchro gear box however this was written nearly 50 years after he drove the Packard. I met the author around the time of the story, he was a very rational man and an engineer.

David

You need to use inner tubes with "bendy" valve stems. You bend them at 90 deg so they exit out the side of the wheel disc through the hole. They hold the shape. I don't recall the US source for the ones I bought here in Australia but they were readily available when I described the problem.

I thought they were painted red, same as as the hexagon in the hubcaps but those photos all show black. I might have to re-paint mine! The 626 Speedster in the Henry Ford Museum has them red for what its worth.

The 6th Series cars all have 8 lug bolts, it sure looks like a a 1929 633 sedan to me. I have an identical car.

Mal,
I have used a family toolmaking business at Blacktown a few times and they were willing to take on very small jobs which they completed promptly. Excellent workmanship and the latest equipment but not exactly handy to Wade's workshop. Call me if you want contact details.
David

That wasn't intended to be controversial! The car with the new core has just returned from its first run a 3,400 tour which was mostly in mild weather. It has a very effective radiator shutter thermostat and an inline thermostat. On the cold mornings it ran at 140 deg F. On the few occasions when the ambient was around 80 F and we were climbing a steep hill it still ran at about 140 F. This is not an assumption it is measured with rebuilt a recalibrated temperature gauge in the cylinder head and touching the head confirmed that it was running too cool. Also the engine is probably not fully run in from a complete overhaul.
Both of the other cars would have boiled under the same conditions.
OK so I need to drive it hard on a long hill when it is 100 ambient and I have no doubt it will go above 140 but the point I am trying to make is that a new modern core is so much better than a honeycomb core that I would not contemplate anything else and if funds permitted I would put modern cores in the other 2 cars.
The in line thermostat will now be set to open at about 170 F.