550 cylinder head

super99

Well-known Member
The older 550 (1963) had a miss, so I ran a compression test with all spark plugs out. 3 cylinders had 110#s and #4 had 60#s. I got the head off yesterday afternoon and the exhaust valve is burned a little. It's been years since I had a head worked on.
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I know that one valve needs replaced, question is, do I have all of the valves ground or just fix the one that needs replaced? Will a machine shop do just one valve or will they want to do all or nothing? The tach reads a little over 5000 hrs. There is a slight ridge in the cylinder walls, I can't catch a fingernail on it, but you can see it. I'm not concerned about that, it will run longer than I will be around. The tractor will have light use, so I just need the valve fixed and call it good. 1/2 of my lifetime ago there was an old guy that had a valve grinding set up in his shop and he would grind and replace valves in the head on my super 88 when it would burn one out running the corn dryer. He is long gone and I don't know of anyone that does it anymore, so it will have to go to a machine shop to be repaired.
I read a lots on here about valve protrusion. I kinda think I have a vague idea what it is but not sure. Is this something I need to be concerned with, or does that only apply to diesel motors? Thanks, Chris
 
All machine shops in my area would want to do all of them. They like to add the "cleanup" and "valve spring testing" to their fees and I guess I don't blame them.
The thing is, I have to take any machine work an hour away from where I live because all the good ones have closed up and this guy keeps saying "It won't be long."
If you can find somebody to do just one valve, do it. However, you will be kicking yourself if another cylinder has a problem six months from now.
 
I'd take the other valves out and look things over if the seats,springs and valves look OK I'd get some valve grind paste and lap them in and put a new valve in number 4 and lap that in too.Probably be better to have the complete head done but it'll cost a lot more.Be sure to put the valves back in the hole they came out of.
 
If the valve seat is in fair condition, it may take only 5 to 10 minutes to recut the seat - longer if it needs more than one angle doing. Lapping in the valve is a different operation. The seat may be good, if it is a hardened insert.


Until you have removed the junk valve, you won?t know what the damage is. As for the rest, check them out now. All the valves will benefit from at least a light lapping. Others may be near end of life. Often depends on how the routine service maintenance has been carried out. Timing, valve clearances, fuel mixture can all be causes. Even worn out valve guides can be troublesome.


Valve protrusion is only important if contact with the piston is possible. Valve recession is far more important for the high compression diesels - for sufficient compression to enable cold starts.


Valve seat cutters are not that expensive. Mine cost me nothing but they will only attack normal seats, not hardened inserts - so were discarded by the place where I got them from.
 
Chris: Does the head have Perfect Circle valve seals installed? Also if the valve burnt, the seat also burned. More details later tonight. J.
 
Not sure about the valve seals. I do not have a valve spring compressor to take them off and check. Chris
 

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