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Brandwag
Samba Member
Joined: November 28, 2015
Posts: 12
Location: Cape Town
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 Posted: Wed Jan 17, 2018 10:51 am Post subject: Help with valve guides |
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Hi, I am redoing heads on a 2.0 l air cooled type 4. I am replacing worn , sloppy valve guides. The new guides pushes in easily by hand, is this OK? I have read somewhere that it is OK if the valve guides move with the valves ,is this true? Is it possible to use some glue to fit them to the head? With the new valves and guides,they fit well together and there is no play between the components.
Thanks for any advice?
Storm me |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21510
Location: Oklahoma City
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| Posted: Wed Jan 17, 2018 10:59 am Post subject: Re: Help with valve guides |
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| Brandwag wrote: |
Hi, I am redoing heads on a 2.0 l air cooled type 4. I am replacing worn , sloppy valve guides. The new guides pushes in easily by hand, is this OK? I have read somewhere that it is OK if the valve guides move with the valves ,is this true? Is it possible to use some glue to fit them to the head? With the new valves and guides,they fit well together and there is no play between the components.
Thanks for any advice?
Storm me |
NO...its not ok that they move...and NO....you cannot use adhesive of any kind.
The proper way is to buy oversized valve guides and then have the machinist ream the guide bores in the head to an interference fit for that specific oversize. Them have the guides pressed in to correct depth...then have the ID reamed to the specific size to fit the valve stems.
In MANY cases...its common that the guides move in the bores...because if you look carefully...the bores or bosses have cracks.
Ray |
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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Wed Jan 17, 2018 11:35 am Post subject: Re: Help with valve guides |
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No. There are many sizes and over sizes of valve guides. The head needs to be heated in an oven to drive them in or out. Then the right size needs to be used, then the seats have to be ground because the new guides will not be centered the same as the old ones. I used to do this for a living on street and racing heads - it isn't something I would even think of attempting without all the needed tools and reamers. The inside of the guide has to be reamed as well after it is inserted. Also the heads should be cleaned, fly cut a slight touch to make sure they aren't warped. The heads also have to be thoroughly checked for minute cracks too. Nice try but rebuilding heads is not a DIY thing except in places where there is no electricity or running water - and then they don't expect them to last or drive over 25 mph cause there are no roads either.
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