Of all the products manufactures & marketed by Speedwell, the very worst were their pathetic valve guides. These were primarily for use in their Alloy heads but were made to the standard BMC dimensions. On the left you can see a typical Speedwell guide after removal from a head, not only is it in two pieces, but the circlip has also began to break up! As the guides were machined with a square section groove for the flat steel circlip, an excellent stress point was created, so when any appreciable side load was placed on the guide (use of high lift rockers for example) it would snap in half!

Once this has taken place, anything can happen.

On the right you can see a guide & circlip manufactured to my own design, these utilise round section circlip's and groves and totally eliminate the original "designed in" problem. These guides are available in Iron or silicone bronze, in standard or oversize. For use in applications where the movement of the original guide has caused ovalisation of the valve guide hole in the cylinder head. If you require a set of these (even though I say it myself) excellent quality guides, contact me direct.