Valve guide replacement

[Hack]

What is the best method of removing / replacing valve guides?

Also, will the seats always need to be re-cut following guide replacement or will lapping-in be sufficient.

Cheers,

Andy

[Pigford]

Get a good professional to do it, they have been known to come loose if not fitted proper like!!!! Steve (Debben) would be a good bloke for advice!

[DogsbolloxofZ1B]

IMHO If you don't have to replace the valve seats then have them relined. If your replacing the seats then replace the guides completely as this will ensure you have perfect axial alignment. Ray Debben & The Cylinder Head shop offer this service.

[Garn 1]

Hack, as Pigford & Dogsbollox' have said it is a job for the pro's, but if your ####-bent on doing it I would approach it this way.

You need a punch .... the diameter to fit into the guide and a shoulder not quite as wide as the guide. Now heat the head in an oven (don't tell the wife!) for about 10 mins at 150 degrees Centigrade. (Or just too hot to handle, unless you have those joined-together gloves things!) and just gentle tap out from the combustion chamber. You may get two done then re-heat.... Don't get heavy-handed or you will remove metal and the new ones will be loose. Install the same way... maybe a little hotter. Have the new guides in the freezer. You will know when they are home it makes a different noise when the little circlip on the new guide bottoms.

Now check with grinding paste to see if you have to re-cut the seat. Alot of times it will be OK with a grind, however, if the guides have been operating for a while with a lot of clearance they could need re-cutting. There is a special tool for this and it does require some expertise. (Seems a bit easy, hope I didn't forget something!).

Regardz.

(Edited by Garn 1 at 11:46 pm on May 26, 2006)

[Hack]

Thanks guys, I have decided to heed the advice and have left my cylinder head with SEP at Kegworth.

Cheers,

Andy

[Pigford]

Garn.... one thing I've always worried about when hand-lapping valves is doesn't the grinding paste work its way inot the valve guides??? Perhaps I just put on too much grinding paste, but it always makes me edgy!!!???

[Garn 1]

Pigford, griding-paste can get to the guides, particularly, if you use too much oil. The stem needs some oil while lapping and the paste needs just a little, but, not enough to run down to the guide. Also, only a small amount of paste is needed. The head is usually in a state where it can be washed, if the guide, inadvertently, has some ginding paste on the guide/stem surface. Rest easy, not much damaged would be caused if this does happen.
RegardZ.