Possible burned valve
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Possible burned valve
Possible burned valve
Recently I changed my plug wires and spark plugs on a 1964 F250 292. I previously used split fire plugs. The 2nd plug on the passenger side from the fire wall had the electrod completely burned off. Could this be caused by a burned valve? If so how can I determine this? Can I do a valve job without having to do a complete engine overhaul? My oil pressure at idle is 60 lbs. and the pressure goes up as I drive. The engine does not smoke. I have 2 oil filters on the engine for added protection and use Amsoil synthitic oil. I would apprectiate some suggestions since I am a novice when it comes to auto mechanics. Also, I want to know is it necessary to replace the heat shields that were attatched behind the exhuast manifolds. Both heat shields were developing holes. I don't know what the purpose of them are. They were not reinstalled when the exhaust manifold gasgets were replaced on Sunday of this last week. 
Recently I changed my plug wires and spark plugs on a 1964 F250 292. I previously used split fire plugs. The 2nd plug on the passenger side from the fire wall had the electrod completely burned off. Could this be caused by a burned valve? If so how can I determine this? Can I do a valve job without having to do a complete engine overhaul? My oil pressure at idle is 60 lbs. and the pressure goes up as I drive. The engine does not smoke. I have 2 oil filters on the engine for added protection and use Amsoil synthitic oil. I would apprectiate some suggestions since I am a novice when it comes to auto mechanics. Also, I want to know is it necessary to replace the heat shields that were attatched behind the exhuast manifolds. Both heat shields were developing holes. I don't know what the purpose of them are. They were not reinstalled when the exhaust manifold gasgets were replaced on Sunday of this last week.
Laughing Gas
Joined: Oct 2001
Posts: 957
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From: Winchendon MA
Possible burned valve
Well first off never use those S**T-fire plugs your wasting your money on a crappy plug. Use Auto-lites in a Ford, and NGK's in imports.
Tell me was the plug with the electrode tight in the hole? My guess is it was not those over heated the elected or it was just a bad plug to start with. Did the other plugs have any damage?
Three things that will do it is.
1) Wrong heat range of the plug. (should be all plugs)
2) Loose in the hole thus no path to rid it self of heat.
3) Detonation. (from hi compression and hi load or contamination from weak oil ring)
4) Just thought of it. Cross fire. How are the wires was this wire laying on top of another cyl wire?
I'd do a compression check on all the cyl first then report back.
Did you install all the new plugs? Did it run okay?
44Dwarf
Tell me was the plug with the electrode tight in the hole? My guess is it was not those over heated the elected or it was just a bad plug to start with. Did the other plugs have any damage?
Three things that will do it is.
1) Wrong heat range of the plug. (should be all plugs)
2) Loose in the hole thus no path to rid it self of heat.
3) Detonation. (from hi compression and hi load or contamination from weak oil ring)
4) Just thought of it. Cross fire. How are the wires was this wire laying on top of another cyl wire?
I'd do a compression check on all the cyl first then report back.
Did you install all the new plugs? Did it run okay?
44Dwarf
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Joined: Nov 2001
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From: Western NC
Possible burned valve
Answers in order:
1) burnt electrode ... I'd guess not caused by burnt valve
2) do a compression check. If one cyl is over 20% lower than the avg. of the 8, squirt a couple or three tablespoons of 30 weight oil in there. If the #'s magically go up, it's rings, not valves
3) Sure. Just take off the offending head(s). An overhaul means replacing parts in the whole thing (cam bearings, mains, rod brgs, etc.). Now, an overhaul might be a good thing to do while you're at it, but no, you could just fix what's broken.
4)60 lbs pressure at idle? R U sure? I'd think 10-15 psi hot is more like it. If I was running 60 at idle, my idle speed would have to be 3,000 rpm. It can't go up a whole lot higher than 60psi., so I'm wondering what you've got going there. Are you running molasses in the crankcase?
5)heat shields are for sparkplug wires that are in close proximity to the exh. manis. I suspect there's a reason why there were there when it came from the factory and I've got a set on mine. Macs has 'em. Lots of other folks, too.
Good luck.
1) burnt electrode ... I'd guess not caused by burnt valve
2) do a compression check. If one cyl is over 20% lower than the avg. of the 8, squirt a couple or three tablespoons of 30 weight oil in there. If the #'s magically go up, it's rings, not valves
3) Sure. Just take off the offending head(s). An overhaul means replacing parts in the whole thing (cam bearings, mains, rod brgs, etc.). Now, an overhaul might be a good thing to do while you're at it, but no, you could just fix what's broken.
4)60 lbs pressure at idle? R U sure? I'd think 10-15 psi hot is more like it. If I was running 60 at idle, my idle speed would have to be 3,000 rpm. It can't go up a whole lot higher than 60psi., so I'm wondering what you've got going there. Are you running molasses in the crankcase?
5)heat shields are for sparkplug wires that are in close proximity to the exh. manis. I suspect there's a reason why there were there when it came from the factory and I've got a set on mine. Macs has 'em. Lots of other folks, too.
Good luck.
Senior User
Joined: Mar 2000
Posts: 113
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From: Connecticut
Possible burned valve
Best way is the wet-dry compression test. If it goes up after the wet test, like it says above, it's rings. If it stays the same on both tests, then you know it's a burned valve. if you burned a valve, it won't run very smooth.
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Possible burned valve
Originally posted by Dan Hazen
Thank you for your replyk. I took out the split fires and put in some boshe plugs and wires and the engine is running smoothly. I noticed when I replaced the plugs that several were not tight even though when I initially put the plugs in they were tight. It is possible though that that one plug was more loose than all the rest. The plugs diffinitly needed changed but only the one had the electrod burned off. Also the plug wires were bunched together.
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Possible burned valve
Originally posted by phjbbu
Answers in order:
1) burnt electrode ... I'd guess not caused by burnt valve
2) do a compression check. If one cyl is over 20% lower than the avg. of the 8, squirt a couple or three tablespoons of 30 weight oil in there. If the #'s magically go up, it's rings, not valves
3) Sure. Just take off the offending head(s). An overhaul means replacing parts in the whole thing (cam bearings, mains, rod brgs, etc.). Now, an overhaul might be a good thing to do while you're at it, but no, you could just fix what's broken.
4)60 lbs pressure at idle? R U sure? I'd think 10-15 psi hot is more like it. If I was running 60 at idle, my idle speed would have to be 3,000 rpm. It can't go up a whole lot higher than 60psi., so I'm wondering what you've got going there. Are you running molasses in the crankcase?
5)heat shields are for sparkplug wires that are in close proximity to the exh. manis. I suspect there's a reason why there were there when it came from the factory and I've got a set on mine. Macs has 'em. Lots of other folks, too.
Good luck.
Answers in order:
1) burnt electrode ... I'd guess not caused by burnt valve
2) do a compression check. If one cyl is over 20% lower than the avg. of the 8, squirt a couple or three tablespoons of 30 weight oil in there. If the #'s magically go up, it's rings, not valves
3) Sure. Just take off the offending head(s). An overhaul means replacing parts in the whole thing (cam bearings, mains, rod brgs, etc.). Now, an overhaul might be a good thing to do while you're at it, but no, you could just fix what's broken.
4)60 lbs pressure at idle? R U sure? I'd think 10-15 psi hot is more like it. If I was running 60 at idle, my idle speed would have to be 3,000 rpm. It can't go up a whole lot higher than 60psi., so I'm wondering what you've got going there. Are you running molasses in the crankcase?
5)heat shields are for sparkplug wires that are in close proximity to the exh. manis. I suspect there's a reason why there were there when it came from the factory and I've got a set on mine. Macs has 'em. Lots of other folks, too.
Good luck.
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Possible burned valve
Thank you for your reply. You mentioned that my oil pressure was to high. It has been running this high after I replaced my worn out oil pump about 3 years ago. Before the oil pressure would be around 15 to 20 lbs. until the pump went out. With the new pump the oil gauge has been about 3 times as high as before and I didn't do anything else but replace the pump. After I start the engine the oil pressure gauge goes up to 60 lbs. and slightly goes up with the r.p.m. maybe just a few pounds. I am running Amsoil 5W-30 and have used it in my truck since the early 70's. As for the heat shields I have the plug wires far enough away form the exhaust manifolds that there should be no problems from heat. Thanks again for your reply Paul.
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Joined: Nov 2001
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From: Western NC
Possible burned valve
The loose plugs are probably telling the story. If they were loose, the ability of the plug to dissapate combustion heat would be GREATLY reduced, so they'd run MUCH hotter than design. That'd explain the burned electrode on one plug and I'd guess the other electrodes on the other loose plugs weren't far behind. In a way, I'm surprised you didn't experience pinging at the least. I don't have a comment on the Splitfires. I've never used 'em and I don't either endorse or throw rocks at stuff I have zero experience with. All I will say is that given what you've mentioned, it's likely that any sparkplug from any manufacturer would have suffered the same fate.
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From: Sun River St. George
Possible burned valve
This is why this is such a GREAT site. That loose plug diagnostic was excellent! Even better the original poster came back and let everyone know that his old Ford was running good. Perfect! I'm off to the show.
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