My '73 1800ES recently developed a mysterious clicking noise. A couple friends agreed that it seemed to be associated with the valves. To test this theory I first checked and adjusted the valves clearance. It's only been a few months since the last time I did this and they were all still good or very close. Next removed the rocker arm shaft assembly and turn the engine over with the coil wire removed. The noise disappeared. When I did this pulled each push rod out to inspect it, non where bent or showed any unusual wear. I shined a flash light and inspected the lifters as best as I could, they all looked normal. Then I warmed the engine up and the noise became even more pronounced. Last, I checked my engines compression; it was an even, though lower than I hoped 130 psi warm. Any ideas about what the noise could be? I'm preparing to replace the cam, lifters, and pushrods will this solve the problem? If it will, any suggestions about what type of cam I should use to replace the existing one? thanks.

Sounds like it's the gear to me. If the cam turns out to be bad don't forget to put the spacer ring from the old cam on the new one. It's not obvious that it's a separate part. The noise you describe STARTED after a cam change & I barely made it home with a broken cam plate. Let us know what you find.

Mike M. Now with Greentoad II in addition to yellowbricktoad

I should clarify. The noise only ceased with the rocker shaft assembly removed. Adjusting the valve clearence did nothing. With the rocker shaft assembly replaced the noise returned.

It's possible you have a worn rocker shaft or worn rocker bushings or both. If you don't mind taking the rocker gear off again I suggest the following. Thoroughly degrease and clean it. Check the springs for breaks. See if any of the rockers have any play in them. You might find some in one or more. These could be the ones that are clicking. On the bench carefully remove everything from the shaft keeping all parts in order and orientation. Inspect the shaft for wear and grooving. Make sure the oil feed hole is clear.
Now, there is a question that I hope someone else can answer here. Is it possible to turn the shaft throught 180º so that the rockers have an an unworn area to pivot on? A new hole for the oil feed will have to drilled as well I think to match the feed in the mounting block too? Not sure about the rockers.
Rocker bushings can wear but it's usually the shaft, especially if it's been run with dirty oil and clogged feeds. If the shaft is bad you might like to try and get another. I think new ones are available but maybe spendy so a good used one may have to suffice.
Keep us updated.
Derek UK

Is it possible to turn the shaft throught 180º so that the rockers have an an unworn area to pivot on?

No, the flats for the bolt heads are on one side only, so you can't flip it over top to bottom. You can turn it 180º front to back.

Get out a ruler and measure how far each valve goes up when open. The total amount isn't so important, but any valve that is shorter than the rest means you'll need a new cam and lifters in short order.

Usually, by the time they make nose they are well on their way to going out.

If they are all even, then it's possible that something is slowly going wrong at the front end of the cam. Either the gears are getting worn, or the thrust plate is getting worn. When the valves are engaged, the cam undergoes back and forth torque at the gear. It pushed each lifter up the cam lobe, and then past the lobe 'TDC' valve pushes the cam forward. So any slack in the valvetrain goes back and forth at idle, making clicking, clunking sometimes rather scary noises. Typically, noises there will go away as the engine is revved up - eventually the cam goes into a constant pull as the valves rebound more weakly and the oil pump gets harder to turn.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

John, "at idle, making clicking, clunking sometimes rather scary noises. Typically, noises there will go away as the engine is revved up" this is a great description of the symptoms I'm experiencing. The noise is the loudest at idle but under load, especially on the freeway, the noise is absent. I also believe that this is accurate because when I turned the engine over by hand to adjust the valves at the crank shaft bolt I heard a clicking noise if I reversed direction. thanks for your help.

Could be the fiber timing gear. Could it be a "clack" rather than a "click"?
When the gear becomes loose on the knurled steel hub it works fairly well for
a while and the noise gradually gets worse and worse and then (if you're lucky)
it will occasionally slip, especially at high revs, and then stick in the right
place when the engine is back to idling speed. It's like you really wrap it
up and then like you turned off the key, but when you step on the clutch and
roll to a stop it's idling perfectly. Happened to me several times on a trip
in my 164 from Cherry Point to Daytona on US 17 around Charleston. Pretty
scary. About 2 weeks after we got back to Cherry Point it quit for good.
That was at a measly 120,000 miles if I remember right, about 1979.
Gotta put those steel gears in it one of these days!
--
George Downs Bartlesville, Heart of the USA!

Yeah, on my PV's orginal B18 the fiber gear came loose from the hub. Revved up it was completely quiet, no indication of any problems at all. But at idle it made the most amazing clatter, sounded like a semi truck diesel engine. When I pulled the timing gear cover off, the fiber portion of the gear actually fell off. It was only being kept on the splines by bouncing off the timing cover apparently. Still, never stranded me - I must have driven it about 40 miles in that condition.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

In the 164 I drove on to Daytona, back home to Cherry Point, and Susie drove
the car several more weeks before it finally let go. Every oldtimer I had
(with the exception of the 444, which I only had for a year) wiped out a
timing gear one way or another. One of them chewed the gear up into about
1½" chunx. Needless to say it didn't run that way. My 122 wagon did it on
the highway less than half a mile from the house and it was REALLY loud, but
did make it home.
--
George Downs Bartlesville, Heart of the USA!