I always get the Butt-Kicker problems. Here are the facts: 1939 Ford Flathead. Just rebuilt (not by me). Has the stock size camshaft with adjustable lifters. The engine has a valvetrain noise. It's one tap per camshaft rotation and you can only hear it at idle and part throttle speeds. I removed the intake and ran the valves (.012" and .014"). I reassembled and started the engine: the noise is still there. I removed the intake and checked the valve lash two more times: none are out of adjustment. I removed the fuel pump push rod and ran the engine: the noise is still there. I also shorted each cylinder one at a time to see if the offending cylinder would make the noise if it did not fire; no change. As a process of elimination, I removed the valves from each cylinder (one cylinder at a time) and ran the engine to find out which cylinder the noise was coming from. It turns out the noise is from the #5 cylinder. With the valves removed from the #5 cylinder the noise is gone. I then ran the engine with the valve installed in the #5 intake, without the valve installed in the #5 exhaust: the noise is still gone. I then removed the intake valve and installed the exhaust valve; the noise is back. The noise is from the #5 exhaust valve. I removed and inspected the valve, guide, spring, retainer, keepers, lifter, checked out the valve lift, valve to cylinder head clearance, valve seat, and lifter bore; I found no problem. So I thought I would swap the exhaust valve assembly for the intake assembly to see what would happen. With the intake valve assembly now installed in the exhaust valve spot and no valve in the intake spot, the noise is still there ...that's weird!! I thought that I would knurl the outside diameter of the valve guide as the valve guide bore seemed just a bit loose. Not so bad that I thought it needed any attention, but I was trying to eliminate all possibilities. After I knurled the guide it was a bit tight in the bore. In fact I had to assemble the keepers and spring with the guide installed in the block instead of the usual way of installing the assembly into the block. I started the engine with the #5 exhaust valve instaled (intake assembly still missing); the noise is still there!! At this point I know that I'm missing something. I even removed the exhaust valve assembly from #5 again and ran the engine just to make sure; the noise is gone with the #5 exhaust valve removed. The noise is most definitely coming from the #5 exhaust valve. What do you think?
I checked the valve lift and it was fine. The lobe ...I guess it could be messed up somehow. I'll get my bore scope and have a look at it...
Do you have access to a variable strobe light? Mine has helped me find some really weird stuff. With the engine running you can adjust the flash till the spring/lifter/stem is standing still and then just speed up or slow down the strobe a tiny bit and the action will be in super slow motion. This might let you see if it's doing something the non-noisy ones aren't.
I don't know anything about flatheads, but your question and story sure did read well and cover all the bases. just read another guys tale trying to figure something out, read it 3 times and I still don't know what he was trying to ask. I need a beer now.
Hummm.... Egged. I'll have to check that. Have you seen that before? Yep, I didn't see anything abnormal... That would be the ultimate, but I don't have any easy ideas to run the engine with the intake off so I can look at the valve. Kinda why I've been swapping parts around instead... Thanks! That was one of the first things I thought about when it still made the noise after I adjusted the valves. Upon inspection of the seat, it did not look abnormal. I got out my outside snap ring plyers and got ahold of it trying to move it. It didn't move at all... I'll check that lifter bore out real carefully in the morning...
If you have a reground cam, it is possible that lobe has a problem. If it was ground with a dull wheel and the wheel was pulled out with a lot of pressure on it when the lobe cleaned up, the runout on the clearance ramp could be excessive. While the engine would run, that valve could be noisy. Another thing that it could be is heel runout due to a bent cam or the cam was ground with bad centers. I have seen all kinds of screwy problems like this over the years.
Do you think that I would be able to see such a thing on the lobe with a bore scope? ...Or could I see it with a dial indicatior??
You have eliminated everything but a defective camshaft. Evidently one lobe has a manufacturing flaw. And congratulations on the best presentation of a question ever. If everyone did their homework and stated all the facts as well as you did, most questions would answer themselves or get answered immediately.
Is the fuel pump pushrod worn down? You may need to build it up a little bit. Also, is there such thing as a flathead without valve noise? I've never heard one. Solid lifters tend to do that.
Well, I ran the engine with the push rod sitting on the bench, so that possibility is out. The Flathead Ford can be as quiet as any other engine... I've listened to some quiet ones before. Ok, looking closely at the cam lobe while turning the engine over with the hand crank showed that on the down ramp of the cam lobe there is a round step about 1/8" past the tip of the lobe. It's about the same diameter as the lifter. The camshaft is junk. Time to start taking all the bolts out... Thanks for the support guys!
Ok, got the cam out. Here is a pic of the offending lobe: (and yeah, I said it's #5 cylinder ...it's really #1 cylinder. I must have had too many beers when I was typing yesterday).
Loudpedal.... Thanks for sharing with us.... Flatmotors do have a bit of valve gear sound, due to the lash. I hope you can get your $ back on the cam. 4TTRUK
Hi, Kris. Good diagnosis, patient and thorough. I was going to suggest what Pete mentioned: excessive runout on the clearance ramp. My recommendation would have been to check lash at the heel, then up to 12* before and after the center of the lobe heel... But what followed was evident, once it was visible. The conclusion echoed Pete's and Rusty's musings to the letter. Congrats on an open and shut case.
At least that one lobe was not ground down to the design base circle diameter. From where the ridge is I would say the base circle needed to go about .030 smaller. If you really liked that cam it could probably be salvaged. Could get expensive though.
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