You need to tell use one thing: What is the largest OD of valve stem seal you can tolerate?

Then you get the ID of the sleeve part of the seal. If you are lucky your guide OD will be 0.500 or 0.530 and you can use stock Magnum motor seals.

If you need to machine the valve guides so the valve stem seals will fit on, you can do it yourself. You need an electric drill, valve guide cutter and pilot.

Attach the pilot to the cutter, chuck the cutter into the drill, lube the pilot and cut down the valve guide. It's that simple. On my '86 318 the valve guide was 0.625, and the stem seals were for 0.625. But the guides stuck up too high if my valve lift exceeded 0.474". So I bought the same cutter and a 3/8" pilot and 15 minutes later I had all my guides OD sized and made cylindrical, and the guides about 0.2" shorter.

One tip: The cutters in the tools are carbide and don't take kindly to shock. I was careless and now I get to hand finish the tops of the guides I cut down.

Total cost less than $100.

Study carefully before you buy. There are cutters for valve seats, cutters for valve guide OD, and cutters for valve guide height. Generally they are two out of the three, for example spring seat and valve guide OD, or valve guide OD and height.

R.