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I understand that fire apparatus required twin ignition as a reliability feature. I may be wrong. It was explained to me that is the reason the Pierce-designed V-12 in the Seagraves have two plugs per cylinder in the heads.

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Thanks, Greg. I looked in the “Wiring Diagrams And Tune-Up Guide” and found 0.005” intake and 0.006” exhaust, which seems reasonable, so I went with it. I hear you about keeping force off the lifter bracket, as I reread all the relevant info I could find in the Forum (your explanation was great and you had cautioned me about this risk in person).

It was quite fiddly to get anywhere near the desired setting but you have done this so you know. My car’s clearances were wide: most were at least 0.010”. I got them as close as possible on a first pass, then started up and let her run at idle about 10 mins. She sure sounder a lot better with the clearances reduced. I shut down and started checking again; found a couple closer than desired so I reset them. I gave out so I retired for the day. I will keep tweeking until I am confident none are too close. Having the flats ground would sure make this job a lot easier!

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Update: to report on this morning’s activity. I used MMO underbeach open intake andvexhaust valve, a couple if good squirts with my oil can with flex gooseneck. I roller Her back to the garage door and a good thing, too: she fired right up smd poured smoke out., as expected. No sign of any sticking. I shot MMO through each spring, onto the valve stem, hoping that the intakes would vacuum some into the guide, and also because plenty of oil just feels right! She idled about ten mins with no problems. I am going to button her up and take a drive later today. I think I have her ready to go and it’s thanks to my PAS friends like Greg and George, and others of course!

Think I will try the balve adjustment and see if I can get these closer to right. Greg what was the correct clearance you suggested to me before?

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Thanks for the information, George. That appears to be an original S80 carb in your photo; my Car has a period-looking but non-original retrofit. I have thought about obtaining an original, but I have been advised maybe that is not such a good idea. My Car does start easily and run well enough as-is.

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I know you are right, Greg: tease accepted with a smile! I was in a rush to try it, you know how that goes. At that time, only one valve had exhibited symptoms. Well, now I know. I am also comfortable my engine is not about to wreck, so I can proceed. After I get ‘er lubed up, I plan to (carefully) adjust the tappet clearance. Looks like Mr.Ev preferred 9-10 thou.

You are also right that there are some very complex and interesting dynamics going on in valve springs. I am dealing with a rash of failures of valve springs in Caterpillar 16CM34 gas engines: these are the 8000 HP units made in Germany. Usually Cat gets it right; not quite this time, apparently.

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Agree, George, and thinks for the knowledge and advice. I will pick up some MMO during lunch.

I have another question: On my Car, there is a fitting on the rear tappet chest cover, piped to a fabricated intake tube designed to hold an air filter. I wonder if this tube is passing so much air through the tappet chest that there is no oil vapor getting to the valve stems. Is this even a good idea? I suspect the engine originally had crankcase ventilation via a draft tube connected at this point, but I am not certain of this. This is a modification added before I got the responsibility of caring for this Car.

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New thought: I know from past experience on industrial engines, that if the valve is partially open when compression pressure rises or combustion occurs, the pressure will push the valve closed, sometimes slam it pretty hard. I suspect that this is the event that is dislodging the keeper, because the valve stem movement could be more rapid than the valve due to inertia of the valve, removing some or enough of the spring force on the spring retainer to allow it to move out of place. Aha!

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I had an new idea: perhaps the issue is sticking intake valves. The valve begins to stick and the increase in force required to open it overloads the spring keeper causing it to shift out of place: perhaps it is worn a little, or just can only take so much. Then I realized the force does not pass through the keeper; only the valve spring force is on the keeper. Oh, well… something caused the tapping sound and the cylinder dropping out at the same time, and the keeper to be partially dislodged, and I believe it is sticking valves.

I plan to lubricate all the valves manually as Greg suggests, and let them soak a while, and see if this resolves.

I am pretty much at a loss as to what has changed to cause this issue to begin, and how to stop it. This has not been an issue since I have owned the Car, until now.

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UPDATE: I followed Greg’s advice: mixed 1/2 transmission oil and 1/2 30W and gave a couple squirts on the valve stem with the valve open. I then barred the engine around with the crank, and started up. I heard tapping immediately (sounded like one valve)along with the dead-cylinder shake. Shut down immediately and looked: this time the keeper on Intake #1 had shifted out of place noticeably. I popped it back in place. barred the engine around a few times with the crank (primer cups relieving compression), then started up. The engine idled smoothly and no tapping. I set a slow but not dead slow idle and watched the action in the tappet chest and saw nothing unusual. After 2-3 minutes I heard the beginning of tapping again, but not as pronounced as earlier so I shut her down. Looking in the tappet chest again, I saw nothing amiss.

Next time I plan to oil each of the intake valves and bar around then allow it to sit and soak for a couple hours before trying it again.

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Hi, Greg, it’s been about a month that I started the engine and got it up to temperature, prior to this event. I understand what you are recommending and I will try it; I have just the device to accomplish this. I will report the results soon. Thanks!

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In searching for information, I reread the excellent information Greg Long provided in response to a query named “Valve Train” in February, 2016, regarding the valve lifter brackets and the care to be taken during valve adjustment. Also, in Jan 2018 Karl Krouch provides info about the lifter brackets which are available as reproductions in case of need.

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UPDATE: finally got dome time in the Car Barn this afternoon. First, I used a mirror and light to look at the upper end of the spring, and it seems to be intact. I then used a pry bar to feel the spring force and it seemed like the other springs. I put the bar against the keeper where it appeared to be out of place and with a little force it popped back into place. I temoved the appropriate spark plug then used a light and mirror to look at as much of the intake valve as possible, and it seemed normal.

I removed all the spark plugs to eliminate compression and cranked the engine around as fast as I could. It seemed I could hear a faint bump every other revolution. Noted for future reference.

I replaced the plug in cylinder 4 then opened the primer cup and it seemed to be developing the expected compression. I replaced all the plugs and looked at some of the tappet clearances. Several including #4 intake have clearance of 0.010 inch. We already knew adjustment was needed.

For my next step I plan to start it to see if the tapping and miss are still there.

What is the possibility something has happened to the cam follower roller?

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Not yet; been working out of town but home tonight. Will inspect as soon as possible.

Meanwhile look at this exhaust valve from a Waukesha 7044 Series 4; think it was about to drop an exhaust valve head in the cylinder?

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By the way: where does one find a new valve spring for a Series 80?

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Thanks; will proceed with the investigation along this path.

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Update: found no loose parts in the tappet chest after looking, feeling with a finger, and using a magnet.

Not a speck of metal anywhere.

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Hi, Peter, I have not done any work prior to this event. I was planning a long-needed adjustment as part of this weekend’s activities, but I was derailed by this development.

I will search the tappet chest for parts as you suggest: it is quite clean so if something is there I should find it. I also plan to study my parts list to become more familiar with the design of the spring keeper.

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Also: I need a valve spring compressor for flathead engines; please recommend one which will work well on the Series 80 engine. Thanks.

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Adding promised photo…

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Agree with Greg about the source of carbon on the intake valve stems.

Needs a little freshening but it is a beautiful example of a high-quality motorcar and it will respond very well to the best care!

BTW I visited a fine shop which rebuilds Rolls-Royce and other classic engines a couple of years ago; Arias pistons were being used there.

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