Valve guides Z1B

[Glen]

I am rebuilding the top end of my Z1B. The valve guides are worn, but not out of limit. I feel that they should be replaced while the engine is out. Has any of you done this and how difficult is it?

Glen

[Steve Cooke]

Hello Glen, Changing the guides is relativley simple, after heating the surrounding area to 250degrees plus the guides can be tapped out using a suitable drift and the reverse to install thats the easy bit, once installed the guides should be reamed with a 7mm reamer and the seats will almost certainly need to be recut as alignment of the new guides cannot be guaranteed.If you replace the guides get a set of rebated ones rather than the original ones which use a circlip as a stop especially on an older engine it's a lot safer and of course new valve seals.

Hope this helps Steve

[Glen]

Steve. Thanks for your reply. I am comfortable in replacing and reaming out the guides, but if I recut the valve seats there could be a chance that they need replacing also. Is this any more complicated, or is there a good chance that the seats will not need replacing?

[Garn 1]

Glen, it's unlikely that the seats will need replacing, They will just require a very light "cut" to square them up to the new guides. This should be done by a pro, unless you have the three cutters required. I have sucessfully lapped them, however, I have seen some that require the re-cut process in full.

Replacing the guides, I find it's best to tap-out all the ones that need replacing in the one setting/ heating. Then re-heat and tap-in. You will know when they are all the way home by the sound when the guide bottoms. Use your wife's/girlfriends oven mittens! They are hot to handle (thats the head, I'm talking about)

The replacing of seats are for the pro!
RegardZ

[Steve Cooke]

Totally agree with Garn1 I would always leave the grinding of seats to a pro and definitely if they needed replacing, thats why my head is in Debbens at the moment to be reground. They shouldn't need much but even a little has to be spot on, there is not a lot to play with and if they have been done before things begin to get tight and although a limited amount can be taken from the top of the valve stems after that it's new seats.

[Rich]

Stick the new guides in the freezer until you drop them in. If the old ones come out easily you will probably need oversize ones

[Glen]

High guys.

As it looks, I have the engineering facilities in my place of work to carry out the work myself. Ovens, milling machines, presses etc. I don't have the valve cutting tools and the more I look at it the more I am concidering paying somebody else to re-furbish the head. No doubt this will not come cheap, but I will ask for some quotes. As I am based in Essex, the club recommends Strymar Engineering (from memory). Can anyone recommend these guys, or another engineering company with the appropriate tooling.

G