How do you determine valve guide wear?
12-16-2002, 03:54 PM
#1
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How do you determine valve guide wear?
I am going to pull my heads since I am getting some excess oil on the plugs and am pretty sure it is either the guides or the seals, maybe both. How do you tell if you have excessive wear on the guides? I plan on replacing the seals since I will have the springs off anyways.
[Modified by Fevre, 2:55 PM 12/16/2002]
[Modified by Fevre, 2:55 PM 12/16/2002]
12-16-2002, 05:43 PM
#2
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St. Jude Donor '07,'13
Re: How do you determine valve guide wear? (Fevre)
As long as the valve dosen't wobble at any depth when you have the valve out. Make sure to clean the end of the valve before trying to take it out. Usually the engine will smoke BLUE at start-up and quit after running for a few minutes if the heads need to be done. If it's the rings the engine will smoke BLUE all the time or when the RPM's are increased. If it's black smoke it's the carb. :yesnod:
12-16-2002, 05:56 PM
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Re: How do you determine valve guide wear? (VBP)
Thanks for the info. Could be I am just getting cyl wash form being to rich but it seems to be more on the passenger side bank than on the driver side with dual exhaust and no cross over. Even more reason to get EFI although I was using an O2 sensor to tune. :)
12-16-2002, 08:00 PM
#4
Re: How do you determine valve guide wear? (Fevre)
stem to guide clearances: 0.0015"intake , 0.002"exhaust, usually it'll be more. Anything above about 0.0035"intake & 0.004"exh will cost power.
A simple way to test: Clean head & valve, make sure no oil is on the stem or in the guide. Lay the head on a flat surface. Push the valve in the head until the stem tip is flush with the guide top. Wiggle the valve and measure the movement up/down. If it's above 0.015" it needs to be fixed.
Loose guides cause faster valve seat wear because the valve doesn't "land" on the proper position when closing.
A simple way to test: Clean head & valve, make sure no oil is on the stem or in the guide. Lay the head on a flat surface. Push the valve in the head until the stem tip is flush with the guide top. Wiggle the valve and measure the movement up/down. If it's above 0.015" it needs to be fixed.
Loose guides cause faster valve seat wear because the valve doesn't "land" on the proper position when closing.
12-16-2002, 09:30 PM
#5
Team Owner
Re: How do you determine valve guide wear? (Fevre)
About the only way I know of is to pull a valve spring and check the valve for wiggle. My car was at one point burning a qt of oil every 200 miles. My guides were WAY sloppy.
12-16-2002, 10:13 PM
#6
Safety Car
Re: How do you determine valve guide wear? (ddecart)
Are they stock heads and how many miles are on them? If the answer is yes and more than 50,000 then they are bad. The repair manual I have said to lower the valve down about a 1/4" and if the stem moves more than .010" side to side it needs to be repaired. You would need a dial indicator to check them by this method. I use the wiggle test stated above.
