How to Change Valve Guides In an Alumimum Cylinder Head
 

How to Change Valve Guides In a 4G63 Cylinder Head


The first thing is to remove the valves, springs, retainers and locks.

https://www.miataturbo.net/attachmen...ine=1333635631

The guides are cracked from the bent valves…
(Sorry about the pic,)

https://www.miataturbo.net/attachmen...ine=1333635631

The tools needed for this is an air hammer, a regular hammer, venire calipers, and the proper sized guide driver.
Also the replacement valve guides are shown.

https://www.miataturbo.net/attachmen...ine=1333635631

Have the head with the deck side up.
With the guide driver in the air hammer, knock out the broken guides.
Take care on not letting the driver get into the head casting.

https://www.miataturbo.net/attachmen...ine=1333635631

Once all the guides are removed, flip the head over. Spray lube/oil in the guide bore (not shown), also lube up the replacement guide. Lightly tap the new guide to start it.

https://www.miataturbo.net/attachmen...ine=1333635631

Once the guides are started, use the air hammer to get them “close” to where they should be.
I would not recommend trying to hand drive the guide fully into place, damage may occur to the tool, the guide, and/or the head casting.

https://www.miataturbo.net/attachmen...ine=1333635631

Once the guides are close, finish set the guides to the proper height. By measuring from the top of the guide to the valve spring pad using the venire calipers.

https://www.miataturbo.net/attachmen...ine=1333635631

Once all the guides are set to proper height, The head will move on to the next part of the repair, Having the seats cut, so the valve seat will be index to the center line of the guide.