Candide

Leakdown test results: #1 - 6% #2 - 12% #3 - 5% #4 - 7% #2 had the rocker off, test had leaked out tailpipe. With this test today, air was coming up through timing chain chamber - valve cover off. Is it possible #2 piston rings (I presume) could now improve with consistent operation?

I did not examine inner spring on the suspect compression valve, but I will now. My leakdown test kit will arrive in a day or two and I will post results. I am anxious about Mike's observation that with the rocker off, the valve would be closed so there should not have been any leakage in the absence of a compromised valve. Its what lawyers refer to as bad facts.

I used to have '70 2000 Roadster that I expect had the same config over the valves. Surprised I did not toss one of its rocker arms. I was young. There may have been one or two missed shifts, arguably at high rpm's. I miss that ride. But got married and wife wanted a house. Wife #1 way gone now. But so is the trusty Roadster. Oh, if we could only replay some moves. Those life-altering big mistakes.

Datsunaholic, I'm not driving her until I personally see all four cylinders pass the leak-down test. And I will check valve lash again. banzai, I was thinking of two gas filters, but questioned adding additional drag on suction side of electrical pump (3psi for Weber). But I will do it, and will pass on the seafoam too. I have no experience with it, and as you say, it is running pretty good at the moment.

I have no credible hypothesis on why it bailed. Structurally, it looks sound. Your compromised valve seat theory made sense. But it has to be firing on all four now. I did not hear any valve chatter before, nor do I now. I have only touched the adjustment on #4 exhaust, and I did that cold for now just to see where we were. I will report on my own leak-down test after I have a kit. Until then, I am scratching my head. 170k on original engine. Changed oil every 2-3k. Can a valve spring get weak? Felt strong when I was asking for some purchase to get the rocker back in place.

Being an advocate of risk/reward analysis myself, I will order a test kit. Do appreciate the advice.

Good news here. Mouse trap spring was still in place, lash pad was laying in plain sight. Rocker arm laying in ditch was just my way of saying I found it laying down between two adjacent springs. I was able to get back in place as you described. Fired it up, and for about 20-30 seconds (seemed longer), clattering and not so smooth running. Then, like one through a switch, no clatter, and purring like a kitten. Took for brief drive on property, and it all held. Still probably should drain the couple gallons of non-ethanol supreme I recently put in. Smells bad from tank having been dormant. From what I have read hereabouts, filling it with some seafoam additive would be advisable. Many thanks to Vancouver Island. Stayed at Victoria Empress just last summer.

Newbie warning, and first post. Am original owner of a 77 Pickup that I have been trying to get running well for longer than I care to admit. Finally caved and took to nearby shop. They fiddled with the usual suspects and then did a compression check and discovered zero compression on number 2. Mechanic called to inform me that engine needed serious work, and the kind they will not do on something so old. Owner later informed me that rings were the problem and just not worth the cost on something so, well, worthless. So I quizzed him some, and discovered they had performed a leak-down test, and air was audible through the exhaust pipe, thus rings. So I get home, and proceeded on the premise that my devoted truck deserved a second opinion on their terminal diagnosis. After a few minutes on the internet I knew it was probably exhaust valve. So, swinging over here, you all said check valve lash. I found rocker arm on #2 exhaust valve was laying in the ditch. My heart filled with relief, and some hate. So, how does one get rocker back on the valve stem? I expect the spring must be compressed, and if so can anyone point me to the proper tool for this engine?