Cylinder Head Pro's WTF
08-11-2009, 08:40 PM
#1
Cylinder Head Pro's WTF
This is what I found when I took a head off an engine with zero compression. I expected to see a hole in top of a piston.
No blown head gasket. These are 049 heads.
I do not see any cracks in the exhaust seats. Before I take them to the machine shop looking for educated opinions
Are the seats beat out from stainless valves w/o hardened seats?
No blown head gasket. These are 049 heads.
I do not see any cracks in the exhaust seats. Before I take them to the machine shop looking for educated opinions
Are the seats beat out from stainless valves w/o hardened seats?
08-11-2009, 10:08 PM
#2
I read somewhere that it has to do with the fuel we get today.
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08-12-2009, 12:28 AM
#3
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I had something like that happen to me on first attempt of a marine sbc.
Basically it was explained that the exhaust valves got so hot, they sucked/hammered the exhaust seats into the heads. Happened to all the ex seats but it took a while before I tore it down.
Basically it was explained that the exhaust valves got so hot, they sucked/hammered the exhaust seats into the heads. Happened to all the ex seats but it took a while before I tore it down.
08-12-2009, 07:15 AM
#5
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I did that once on a 351 Ford in my Sea Ray. A mouse built a nest in my thru prop exhaust. The the exhaust valves must have gotten real hot and beat my (also soft seats) seats 0.060" into the head.
08-12-2009, 07:40 AM
#6
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This is what I found when I took a head off an engine with zero compression. I expected to see a hole in top of a piston.
No blown head gasket. These are 049 heads.
I do not see any cracks in the exhaust seats. Before I take them to the machine shop looking for educated opinions
Are the seats beat out from stainless valves w/o hardened seats?
No blown head gasket. These are 049 heads.
I do not see any cracks in the exhaust seats. Before I take them to the machine shop looking for educated opinions
Are the seats beat out from stainless valves w/o hardened seats?
08-12-2009, 07:45 PM
#7
Registered
Jim,
Basically what happens is ... the valve gets so hot that every time it closes, it microscopically welds itself to the seat. Then when it opens it puls a small amount of material off the seat. Keeps happening for a long time until you get a valve sunk in the head. That is one reason why most big blocks have valve rotators in stock form.
The solution is to put hardened seats in the heads, but you have to be VERY careful with Big Block heads with the larger exhaust valves. I have done a few sets, but I tell my customers up front that there is a very good chance that while cutting the head out for the new seat, we might just strike water. If you do, the head is junk
You have to use a fairly shallow seat and not much larger diameter than the valve is. Also, dont be real surprised if a magnaflux inspection finds some cracks in that seat.
The other thing you need to look into after you fix the head is .... if this is the only seat that got beat out, there might be an underlying cause. Something causing that cylinder to run a lot hotter in the combustion chamber than the rest of them. Vacuum leak ? Bad Injector (if EFI) etc.
HTH
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Basically what happens is ... the valve gets so hot that every time it closes, it microscopically welds itself to the seat. Then when it opens it puls a small amount of material off the seat. Keeps happening for a long time until you get a valve sunk in the head. That is one reason why most big blocks have valve rotators in stock form.
The solution is to put hardened seats in the heads, but you have to be VERY careful with Big Block heads with the larger exhaust valves. I have done a few sets, but I tell my customers up front that there is a very good chance that while cutting the head out for the new seat, we might just strike water. If you do, the head is junk
You have to use a fairly shallow seat and not much larger diameter than the valve is. Also, dont be real surprised if a magnaflux inspection finds some cracks in that seat. The other thing you need to look into after you fix the head is .... if this is the only seat that got beat out, there might be an underlying cause. Something causing that cylinder to run a lot hotter in the combustion chamber than the rest of them. Vacuum leak ? Bad Injector (if EFI) etc.
HTH
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
08-12-2009, 08:40 PM
#8
Registered
Jim,
Basically what happens is ... the valve gets so hot that every time it closes, it microscopically welds itself to the seat. Then when it opens it puls a small amount of material off the seat. Keeps happening for a long time until you get a valve sunk in the head. That is one reason why most big blocks have valve rotators in stock form.
The solution is to put hardened seats in the heads, but you have to be VERY careful with Big Block heads with the larger exhaust valves. I have done a few sets, but I tell my customers up front that there is a very good chance that while cutting the head out for the new seat, we might just strike water. If you do, the head is junk You have to use a fairly shallow seat and not much larger diameter than the valve is. Also, dont be real surprised if a magnaflux inspection finds some cracks in that seat.
The other thing you need to look into after you fix the head is .... if this is the only seat that got beat out, there might be an underlying cause. Something causing that cylinder to run a lot hotter in the combustion chamber than the rest of them. Vacuum leak ? Bad Injector (if EFI) etc.
HTH
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Basically what happens is ... the valve gets so hot that every time it closes, it microscopically welds itself to the seat. Then when it opens it puls a small amount of material off the seat. Keeps happening for a long time until you get a valve sunk in the head. That is one reason why most big blocks have valve rotators in stock form.
The solution is to put hardened seats in the heads, but you have to be VERY careful with Big Block heads with the larger exhaust valves. I have done a few sets, but I tell my customers up front that there is a very good chance that while cutting the head out for the new seat, we might just strike water. If you do, the head is junk
You have to use a fairly shallow seat and not much larger diameter than the valve is. Also, dont be real surprised if a magnaflux inspection finds some cracks in that seat. The other thing you need to look into after you fix the head is .... if this is the only seat that got beat out, there might be an underlying cause. Something causing that cylinder to run a lot hotter in the combustion chamber than the rest of them. Vacuum leak ? Bad Injector (if EFI) etc.
HTH
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
08-13-2009, 06:59 AM
#9
Registered
heat caused the issue, either was running real lean, overheating, or had small amount of water getting in pushing temp way up...need to find the base problem..Rob
08-13-2009, 09:31 AM
#10
Thanks for your reply’s guys, it confirms what I thought. Unfortunately all four heads are going to be headed to the scrap heap. The heads are from 1973 and did not have hardened seats. I purchased the boat this spring with the engine build receipts (13K include engines installation) from a shop in Mesa Az. The engine builder (no names mentioned) is supposed to be a professional. I build engines as a hobby but all the mistakes I am finding I hope the other engine (I replaced one with a spare already) makes it until the end of boating season, late Oct in Ne. So If you see someone posting WTB Cylinder Heads its probably me trying to buy some more time for engine #2.
