Cylinderhead
Here I will present some basic information about building a durable cylinderhead for the 175. What type of parts work best, what they should look like and how they should be installed.

 

175-Cylinderhead-1.jpg (19162 bytes) Here is what a finished cylinderhead should look like. Clean, flat gasket surface, combustion chambers smooth/polished, valves cleaned of all deposits. Valves in this head are stainless steel, 1mm oversize, exhaust valves are special alloy stainless steel to tolerate very high heat.

Both intake and exhaust valves are made from "blanks" meaning they have to machined to fit from a generic size valve. I'd give you the part numbers and sources but that would make things too easy.
Guides-1.jpg (17902 bytes) Here we see a set of valves and guides removed the from the head.

At the top, from left to right are: SS intake valves, SS exhaust valves (with guide "blanks" slipped over them), and stock exhaust valves.   The stock exhaust valves can be quite durable if properly prepared.

On the bottom from left to right:
Stock valve guides, used bronze guides, newly machined bronze guides.

The bronze guides are also machined from blanks as seen on the top row. The tops of the guides come ready to accept late model valve stem seals.

Bronze guides will eventually become a necessity on a high performance engine, they retain oil better, wear the valve stem less and are less prone to binding in the high heat encountered in a race engine.
Guide-tool-1.jpg (8729 bytes) This is the valve guide installation tool I made. The long thin tool on the bottom is for driving the guide in and out of the head. The smallest diameter section fits very precisely into the guide bore. The large spacer helps to align the tool and guide for installation.....using the large flat ends to sit on the valve spring seat to keep everything aligned. The small spacer is used with the tool to ensure that the guides are installed at the proper depth.
Valve-1.jpg (15867 bytes) Here is a problem I've encountered with SS valves. Note the "cupping" of the sealing surface of the valve. This was more than likey due to the valve seat being improperly cut, or just worn out, leaving a slightly rounded surface for the valve to seat against. With the high spring pressures used in a race engine the "rounded" valve seat will pound it's shape into the valve.

To help prevent this and to ensure proper valve sealing it's always best to check the valve seats and re-cut as necessary to provide a nice flat sealing surface and all the proper valve seat angles.
Valve-3.jpg (20069 bytes) Another image showing the "cupping". Note the small gap where the ruler meets the sealing face of the valve..you can see light between the ruler and the face. That's not good.