Z1OwnersClub GB

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

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

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?

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

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.

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

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