Stuck Valve ???
09-30-2007 | 06:39 PM
#11
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From: Upper Chesapeake Bay
Noise,
Actually, engine coolant temperature is usually not the problem. The problem is with combustion chamber temperature. If the one cylinder is a little lean, or the timing is retarded, etc and the valve itself, not water temp, is too hot, the valve actually expands and sticks in the guide. You mentioned that your EGT was high .... this is probably a clue to the real cause. A blocked water passage to the area involved might make it worse, but I bet if you track down your egt problem, you will stop sticking valves.
Also, what is the actual guide clearance you are running ? Honing the guides is the preferred method of sizing.
Hope this helps,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Actually, engine coolant temperature is usually not the problem. The problem is with combustion chamber temperature. If the one cylinder is a little lean, or the timing is retarded, etc and the valve itself, not water temp, is too hot, the valve actually expands and sticks in the guide. You mentioned that your EGT was high .... this is probably a clue to the real cause. A blocked water passage to the area involved might make it worse, but I bet if you track down your egt problem, you will stop sticking valves.
Also, what is the actual guide clearance you are running ? Honing the guides is the preferred method of sizing.
Hope this helps,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Is there a number I can call you?
Thanks
Mike
09-30-2007 | 07:20 PM
#12
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Posts: 1,074
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From: Waldorf, Md
Mike,
You can call me Monday at 301-843-5700. I have not seen any problems with the Dart guides "shrinking" but 90% of the engines I see are automotive applications. Have you measured the valve and compared it to a new one ? What brand valves ? Is the valve job done properly ? Too narrow of an exhaust seat will not allow enough heat to get transferred out of the valve into the cylinder head. Too much seat runout will do the same.
Bill
You can call me Monday at 301-843-5700. I have not seen any problems with the Dart guides "shrinking" but 90% of the engines I see are automotive applications. Have you measured the valve and compared it to a new one ? What brand valves ? Is the valve job done properly ? Too narrow of an exhaust seat will not allow enough heat to get transferred out of the valve into the cylinder head. Too much seat runout will do the same.
Bill
09-30-2007 | 08:20 PM
#13
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From: Upper Chesapeake Bay
Mike,
You can call me Monday at 301-843-5700. I have not seen any problems with the Dart guides "shrinking" but 90% of the engines I see are automotive applications. Have you measured the valve and compared it to a new one ? What brand valves ? Is the valve job done properly ? Too narrow of an exhaust seat will not allow enough heat to get transferred out of the valve into the cylinder head. Too much seat runout will do the same.
Bill
You can call me Monday at 301-843-5700. I have not seen any problems with the Dart guides "shrinking" but 90% of the engines I see are automotive applications. Have you measured the valve and compared it to a new one ? What brand valves ? Is the valve job done properly ? Too narrow of an exhaust seat will not allow enough heat to get transferred out of the valve into the cylinder head. Too much seat runout will do the same.
Bill
I'll call late afternoon.
10-01-2007 | 09:08 AM
#14
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Posts: 175
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From: Michigan
Are you running cross overs? I had the same problem on a boat I had with triple 510's. It happened on each of the engines. What I did after the recomendation of several good engine builders in Michigan was put the stock water pumps and thermostat housings back on, and it took care of my problem. What I was told is in the colder Michigan water It is important to keep engine temp at a constant. I am not sure what the water temps are like in Delaware.
I hope this helps you out. It took care of my problem.
I hope this helps you out. It took care of my problem.
