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  #26   IP: 162.245.50.230
Old 01-12-2022, 10:35 AM
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Scratchee, you use the feeler gage just like when adjusting the valves between the tappet and the top (bottom on a flathead) of the valve stem. The clearance should be around .012 when the valve seats so using a thicker gage just give a little extra kick on the opening stroke. NOTE, the only time there is contact between the valve and tappet is when the cam is pushing it open and the valve spring is pushing it back down following the cam to the seat, once on the seat the tappet will drop another .012" giving your valve clearance. That is how a solid lifter tappet works.
There is a ramp angle ground into the cam that uses that .012" gap to "GRADUALLY" contact the tappet instead of just slamming into it. There is far more to a "simple" cam profile that most would think.

When a valve sticks it sticks while traveling back down following the cam profile just as it does on the way open, this is the "valve timing". As the cam pushes the tappet the tappet pushes the valve open against the spring pressure. Once the valve reaches fully open the "spring'' pushes the valve back to it's "seat" and holds it tight against the cam profile. So if the engine turns with stuck valves they are sticking on the top of the stroke or on the way back down. Because if they stick on the way open the engine stops turning or something breaks!!!

Adding a bit more "lift" by using a thicker gage just gives the valve a lil extra push usually breaking it free at the top. Once you have some motion of the valve the oil can get worked in and the valve should follow the tappet following the cam profile. It does not take much movement to get the motion started again and the spring will push it a closed a little more each revolution. Just don't add a bunch more spacing as you don't want to "bottom out" the spring coils.

I strongly suggest using the starter motor with the spark plugs removed and fully charged batteries. This spins the engine fast work the oil pump to keep the oil moving through the engine properly. Turning by hand will not keep the valve tappets oiled against the cam lobes.

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  #27   IP: 165.225.76.100
Old 01-12-2022, 01:27 PM
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Quote:
Originally Posted by Brimikeg View Post
In fact with the tappet at it's farthest position up there is still about 1/8-1/4 inch of space between the bottom of the valve stem and where it is supposed to contact it.
.
this is very surprising: I cannot imagine how the valve could "freeze" in a higher position than the one the tappet would reach on the highest position, as this would mean that something would "pull" the valve stem up fighting the spring, and then stop moving to have gunk/corrosion/combustion residue block the valve... this is extremely strange

To say it differently: what usually happens is that the engine is stopped for a long time, sometimes with sea water flowing back from wrong exhaust design, and the stems / top of the valves freeze, but during that process the bottom of all the stems are lying on the tappets, pushed by the springs. No way for the valve to freeze "in the air"

Something does not add up here
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  #28   IP: 69.250.111.245
Old 01-12-2022, 11:28 PM
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I agree surcouf...let's see what comes back at us!
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  #29   IP: 162.245.50.230
Old 01-13-2022, 10:11 AM
Dave Neptune Dave Neptune is online now
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Surcouf, what do you mean by frozen in the air?

The valves stick on the way down as they are mechanically forced up via the cam lobe and the tappet riding on the cam. They will remain in this position when the engine is turned off. When the engine is off is when the valves get sticky and once sticky when you try to restart the cam forces the "stuck" valve open ( or breaks it ) and as the valve is being "guided" closed it sticks sometimes at the top or any where in between causing zero compression. The gap you see is seeing a valve stuck along its path down and that gap is the tappet following the cam lobe down unlike the valve. You will only see this if you try to restart as the valves will always lay on the tappet's or have the proper clearance of .012" when shutting down a proper running engine.

The valves can't go much further "up or open" either than the cam profile as the springs are almost completely collapsed when the valve is fully open in almost any engine.

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  #30   IP: 165.225.20.168
Old 01-13-2022, 12:24 PM
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Wink

Quote:
Originally Posted by Dave Neptune View Post
Surcouf, what do you mean by frozen in the air?

(...)
The valves can't go much further "up or open" either than the cam profile as the springs are almost completely collapsed when the valve is fully open in almost any engine.

Dave Neptune
Dave,

I am reacting to this previous quote
"Scratchee, that is exactly the case as shown in your photo, the spring does not move up and down and the valve stem doesn't come into contact with the tappet. In fact with the tappet at it's farthest position up there is still about 1/8-1/4 inch of space between the bottom of the valve stem and where it is supposed to contact it."

This would mean that the bottom of the valve stem is frozen 1/8 to 1/4" above the highest position of the tappet when rotating the engine. I cannot figure out how the valve could have "forced the spring" to climb that high, and freeze in place, without being pushed up by the tappet.
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  #31   IP: 162.245.50.230
Old 01-13-2022, 12:51 PM
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Perhaps they were pushed up by the attempt to free it with the "allen wrench". There's really no other way I can imagine.

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  #32   IP: 73.205.183.45
Old 01-14-2022, 12:55 AM
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Quote:
Originally Posted by Dave Neptune View Post
Perhaps they were pushed up by the attempt to free it with the "allen wrench". There's really no other way I can imagine.

Dave Neptune
I suppose that may be a possibility, however I don't think so. If I remember correctly the gap was already existing before I tried to move the valve. That being said I got a little excited when I could see the actual stuck valve (as before it was just a suspicion) and so I got right into trying to free it up. So I suppose it's possible in my haste to try and free the valve I pushed it further up but I am really unsure to be honest, in most cases the simplest solution is the cause, especially if there is not really another way for it to happen.

It's now been soaking in penatrating oil for about a week, I'll be back at the boat on Saturday morning so I'll try to free up the valve from the valve cover side. The head gaskets I ordered came in already so if it comes to it I'll do that this weekend as well. If a valve is this stuck, is it advisable to change it. I have some spare valves lying around somewhere for the engine, but it's a really tight space to try and remove the spring and such, but I can do it if it's in the best interest of the engine. And if I have the head off I can do it then rather than install the head and get the valve stuck again...
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Old 01-14-2022, 05:07 AM
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I would personaly try everything possible from the valve cover before trying to remove the head. Several guys in this forum remove head in 15 minutes... for me it is many hours. Removing the head could open many more cans of worms: damaged or leaking studs, having to re-thread etc. So unless there is a suspision of damaged head gaskets, I would really advise to keep trying to free those valves, as much as your agenda, boat location vs home, boat ambient temperature , ability to drink beer in the boat etc... allow for.

So rotating the valves from the valve cover, spray very generously while cranking directly through admission after removing carburetor / wait / spray more, spray even more / push valve up / wait / spray (WD40, Kroll Oil whatever works) patience is key.

Once you get to free them, warming nicely the engine, and running it at reasonnably high rpm could/might break loose whatever corrosion / gunk accumulated on the valve stems, getting your compression back.

After that, removing head and valves is a very gratifying job for sure
Good luck
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  #34   IP: 73.27.33.134
Old 01-15-2022, 11:04 PM
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I got it moving!
I am able to move the valve but I have to use an Alan wrench to bush it down from the spark plug hole then the tappet to push it back up. I worked some penatrating oil into the valve to work it around a bit. Should I just continue this process of working penatrating oil in or is there a better way to get it moving on its own?
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  #35   IP: 162.245.50.230
Old 01-16-2022, 09:46 AM
Dave Neptune Dave Neptune is online now
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Once the valves are moving even if not all the way, they are moving. Keep the spray into the cylinders going and spin on the starter. If the motion increases a bit just go ahead and start it. At engine speed of hi idle should shake the valve completely loose in a few minutes.

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