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Stellite welded exhaust valve?
I have six new exhaust valves for my 930. These are AE valves PN V94269. The catalog tech data I looked up stated the material of the seat area on each valve is Stellite welded. My previous experience with SAAB turbo exhaust valves with the same Stellite coating on the seat is that no cutting or grinding of the valve is allowed during rebuild. Do I tell the shop doing my heads to leave the valves alone and only do the 3 angle valve job to the heads?
Thanks David Last edited by reclino; 11-18-2016 at 03:49 PM.. |
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11-18-2016, 12:22 PM
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83 911 Production Cab #10
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If the valve have been "Stellite Finish" which was apply using a welding technique, I would leave them as is.
I'm sure our friend from the UK with far more technical knowledge will chime in. http://specialmetals.ir/images/technical_info/Total/Guidelines%20for%20hardfacing%20onto%20steels.pdf
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Who Will Live... Will See  83 911 Production Cab #10, Slightly Modified: Unslanted, 3.2, PMO EFI, TECgt, CE 911 CAM Sync / Pulley / Wires, SSI, Dansk Sport 2/2, 17" Euromeister, CKO GT3 Seats, Going SOK Super Charger |
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11-18-2016, 01:44 PM
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Picture of catalog page.
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11-18-2016, 02:18 PM
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11-18-2016, 02:19 PM
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MB stem material
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11-18-2016, 02:21 PM
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Puny Bird
Join Date: Nov 2002
Location: Port Hope (near Toronto) On, Canada
Posts: 4,566
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On almost all valves the stem is welded to the mushroom head.
Take a magnet to your valve, I bet the stem is magnetic and the head is not. On aircooled engine rebuilds I always replace the exhaust valves, but that's because of the heat cycling the old one has seen. Custom grinding a new valve (within reason) won't hurt anything.
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'74 Porsche 914, 3.0/6 '72 Porsche 914, 1.7, wife's summer DD '67 Bug, 2600cc T4,'67 Bus, 2.0 T1 Not putting miles on your car is like not having sex with your girlfriend, so she'll be more desirable to her next boyfriend. |
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11-18-2016, 02:28 PM
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Max Sluiter
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Stellite is a cobalt-chrome alloy if I understand correctly. Hard and resistant to high temperature. Not sure why that as a valve seat material would preclude lapping the valve.
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1971 911S, 2.7RS spec MFI engine, suspension mods, lightened Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance |
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11-18-2016, 07:56 PM
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No problem lapping. I asked about cutting the valve. I have been reading a bit more and it seems more common to cut extra angles on the inlet valve. I will talk with the machine shop about it.
Thanks David |
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11-19-2016, 04:38 AM
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83 911 Production Cab #10
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Yes, they can be machined but it's not easy as material that has been "stellited" is very hard. Not an job for every shop.
Anyone done any milling on Stellite 6? https://www.researchgate.net/publication/259161481_Study_on_machinability_of_a_stellite_all oy_with_uncoated_and_coated_carbide_tools_in_turni ng
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Who Will Live... Will See 83 911 Production Cab #10, Slightly Modified: Unslanted, 3.2, PMO EFI, TECgt, CE 911 CAM Sync / Pulley / Wires, SSI, Dansk Sport 2/2, 17" Euromeister, CKO GT3 Seats, Going SOK Super Charger |
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11-21-2016, 10:19 AM
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Puny Bird
Join Date: Nov 2002
Location: Port Hope (near Toronto) On, Canada
Posts: 4,566
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Quote:
Every engine shop has a valve grinding machine, we don't mill valves. 
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'74 Porsche 914, 3.0/6 '72 Porsche 914, 1.7, wife's summer DD '67 Bug, 2600cc T4,'67 Bus, 2.0 T1 Not putting miles on your car is like not having sex with your girlfriend, so she'll be more desirable to her next boyfriend. |
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11-24-2016, 04:31 AM
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1986 Porsche 911 turbo
Das Babe
Das Babe Metalberiech
1971 Porsche 911S
