installing oversize valve and relocating the valve guide

[ampor]

What do machinists do when they install a larger valve and move it over a bit? This is in an 2 valve alloy head with an installed guide and seat.

When a larger valve is desired and it needs to move due to interference with the exhaust valve, what is typically done to relocate the valve guide?

Is the guide driven out and the hole welded up (along with the seat register), then machined for a new guide and seat?

Or is a larger valve guide "blank" installed and then offset drilled to accommodate the relocated valve?

Just curious about how this is done.....

Thanks

[ampor]

Thanks for the reply, that's pretty much what I suspected.

For an oversized guide, what grade of iron is desirable? I'd rather use iron than bronze for intake guide material.

[ampor]

Thanks for the reply and insightful information. I hadn't thought of making an offset guide on the lathe and then installing it; getting it indexed correctly would have to be done very accurately I suppose. I appreciate your advice on drilling long, deep, and straight holes.

Puma said: "By the time you've made the guide bore offset, remachined the valve spring seats, fitted new seat inserts concentric to the new guide position, ported the valve throats and ports and solved any cam and valve lifter issues which the new valve centres cause you'll wish you'd never started."

Yes, it is a lot of work, but since I've retired I've always wanted to try and do this. I have access to a lathe and mill, and have lots of free time. I'll give it a try and report back in the future.

Again, thanks for the advice.