pressing out valve guides

sprie · Sep 2, 2023

Having watched a video or two on youtube, i was thinking this was going to be fun. I have a fairly cheap, standard press, which i have found to be very useful in the past.
However, when i got the cylinder head on the press, i noticed that the valve guides are not vertical in relation to the head. If i leave the head flat on the press, the press will be pushing my punch at a bit of an angle, and i am worried that it might bend something rather than push the guide out.
Any advice on what is best approach?
I did start to wedge some bits of wood under the head, to see if i could set the guide angle to be vertical, but this didn't look like it was going to work.
So i stopped, and have posted this question instead.

guineafowl21 · Sep 2, 2023

I’ve not done it, but watched the engineering shop do them on my super Dexta head. They milled off the protruding part (to stop it mushrooming and jamming), then used a mandrel in the end of a hand-held air hammer to rattle them out.

You might achieve the same by chopping/grinding the excess off as close as you dare to the head, then using a hammer and top hat-shaped drift.

steve2286w · Sep 2, 2023

Agree yes

Hammer and drift

tottot · Sep 3, 2023

Not done a Landy, but as above on my Vauxhall just drifted them out, use a correct size drift not something undersize.

divie · Sep 3, 2023

When I did mine I just turned a suitable drift on the lathe and tapped them out with a hammer.
Same drift to fit the new ones. From memory the location / valve stem diameter is 11/32"

Bobsticle · Sep 3, 2023

I beat the bejesus out of them until they were free. Then beat the new ones in. On a folded towel obviously. I’m not an animal.

The biggest issue is the new guides squishing in a bit reducing the internal diameter. You’ll soon know if this has happened coz the new valves will bind slightly. That’s when you have to get an appropriate hand reamer to get them back to size.

sprie · Sep 3, 2023

i got them out in the end. I staggered the supports on the press, which resulted in an angle that just about matched that of the guides in the head. I am about to put the new ones in a freezer for a couple of days before trying the get them back in.

guineafowl21 · Sep 3, 2023

sprie said:
freezer for a couple of days

A couple of hours would be more than enough.

Might be more effective to warm the head up, for two reasons:
1. You can get a greater temp difference by heating - -18deg is your limit with a normal freezer.
2. The head has more thermal mass, so won’t cool so much and jam the guide as you try to press it in. If you rely on a cold guide, it will heat up quickly in contact with the head, sometimes quicker than you can drive it in.

^^^ obviously, everything’s relative, so you might get jamming problems either way round if you’re not quick enough. I’ve had more success with press fits with a hot big part than a cold small part.

pressing out valve guides

sprie

Active Member

guineafowl21

Well-Known Member

steve2286w

Well-Known Member

tottot

Well-Known Member

divie

Well-Known Member

Bobsticle

De Villes Advocaat

sprie

Active Member

guineafowl21

Well-Known Member

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