"It ran well when I parked it!"
 

As the saying goes: "It ran well when I parked it!"
It has been sitting in the garage for a little more than a year. Tried to start it the other day. Fired right up, but running very rough, almost like weak and intermittent spark, or maybe a cylinder not firing.
Investigation and tests show:
- Drained fuel tank, replaced with fresh gas. Good flow.
- Good spark at distributer and all plugs.
- Compression check, #4 = 95, #3 = 95, #2 =95, #1 = 0,
AHA!! That might be the problem!

No apparent leak around head gasket.
No metallic sound ( with or w/o stethoscope.

Any additional thoughts?
What would be your plan of attack?

Re: "It ran well when I parked it!"
 

Not uncommon for a valve to stick open when setting for a long time.
You can verify by pulling the side cover or you could be able to look into the cylinder thru the plug hole. I have a buddy that got a real good bore scope attachment for his smart phone, cheap.
The problem is that the crud that is hanging the valve is on the top of the stem. Pulling the manifolds will let you get to the valve stems.
I'd soak, using Seafoam on the valve stem(s) to free it up. It eats carbon...Marvel Mystery oil too.
That's my plan of attack though I might just go to pulling the manifolds first and see if it is obvious that a valve stem isn't moving and save a side cover gasket.

Good luck

Re: "It ran well when I parked it!"
 

Might try sucking in some MMO through the carb before any major disassembly.

Re: "It ran well when I parked it!"
 

Yep, i agree. Sounds like a hung valve.

You can try freeing it thru the plug hole, or, pull the side cover. The manifolds don't have to be removed.

Re: "It ran well when I parked it!"
 

Marvel Mystery Oil. Pour it into the cylinders and in gas. Let it sit for a couple of days. Than start it up and go for a drive.

Don’t start taking things apart.

Enjoy.

Re: "It ran well when I parked it!"
 

Re: "It ran well when I parked it!"
 

Thanks for the quick (and pretty much unanimous) responses.
Tomorrow I'll be off to the auto parts store to pick up some MMO.
Seafoam was also mentioned. That's new to me, but I'll look into it.

I'll update you with the results in a day or two.
Thanks again!

Re: "It ran well when I parked it!"
 

Use a plastic squirt type bottle and squirt it at the valve stem thru the spark plug hole. Some sort of penetrating oil will do. Lots of smoke when started.

Re: "It ran well when I parked it!"
 

if you know someone who wears contacts - those contact solution bottles have a tiny opening in the tip to shoot a fine stream (think like pencil lead width) exactly where you want it. Fill with MMO and hit right on the valve stems.

Re: "It ran well when I parked it!"
 

That is exactly what I would do too. Worth a try. Simpler than starting to pull parts off. Breaking a mounting stud on your intake, etc.

I have been a firm believer in MMO in my gasoline for years for the old cars. Today's dry gasoline loves to stick valves. We had that in the Flathead. Ever since the MMO treatment it came out of running rough and purrs like a kitty!

Re: "It ran well when I parked it!"
 

A number of responses say to remove the manifolds. Why would they be removed just to free up a valve. The side cover comes off pretty quickly and easily.

Re: "It ran well when I parked it!"
 

UPDATE:

I followed the game plan from above - MMO in the oil and as best I could to the valves as well. replaced the plugs and fired it up. Ran it at a moderate idle for about 4 -5 minutes. No sign of change or improvement.

So I shut it off and , with a big pout on my face, I removed the valve cover (without removing the manifolds or the carburetor), and this is what I saw!
Attachment 471565

Can't push it up, can't pull it down.
Is there a recommended procedure to follow at this point short of pulling the head and delicately addressing the valve with a hammer?!

Re: "It ran well when I parked it!"
 

Squirt some MMO or other penetrating lube in at the top as described above and leave it alone. You might have to add more lube but once should do it. One morning, you'll come out to the garage and see the valve has returned to its proper position. Patience is a virtue here and tearing into pulling it apart will probably prove to be a waste of time.
I've never used MMO - too expensive at $110 for a US gallon. That's only 3.8 litres.

Re: "It ran well when I parked it!"
 

After soaking the stem top and bottom for a day or two, then use a thin Vice Grip to grab the bottom and see if it will turn and drop down. Slow careful back and forth motion on the vice grip might do the trick.

Re: "It ran well when I parked it!"
 

Yep, I agree. Some SeaFoam, penetrating oil, etc, sprayed from the top and bottom should help. Pry and tap straight down on spring retainer. It'll free up.

Then repeat the process to make sure its free before buttoning it up.

Re: "It ran well when I parked it!"
 

Can use ATF and Acetone 50 -50 mix or Kroil
Bob

Re: "It ran well when I parked it!"
 

If the MMO and soaking doesn't do the trick, take your valve spring compressor and remove the spring...if possible, you may be able to work it loose after that...and I can't stress this enough...do not push it up anymore.

Re: "It ran well when I parked it!"
 

I love kroil, its the one stuff that finds a way out of its own can. Wish it wasnt so dang expensive.

Re: "It ran well when I parked it!"
 

I also like Kroil, which cost me $18 for the last can.

Gibbs is also a very good penetrating oil for about the same price.

Re: "It ran well when I parked it!"
 

Alright, last night I pulled off the manifolds and applied a generous amount of MMO to the top of the valve guide. Repeated the application again this morning, and will again this evening if necessary.

I'm investing a great amount of patience with this adventure!
I'm thinking about trying to locate some Kroil if it hasn't come loose by tonight

I'm grateful for the helpful suggestions and the interest you've shown in helping me through this.