New colour,specially heat treated mangonese bronze guides.Although Silicon bronze valve guides were used for their extremely good wear values, they were very hard and not user friendly when fitting. We therefore introduced Manganese bronze guides which have good cutting properties and good wear characteristics and are original equipment on Porsche and Mercedes. Minispares use the mangonese bronze guides and have them specially heat treated for performance use. These valve guides are recommended when using all EN21 4N stainless steel valves. Exhaust valve guides should be opened up 1/2 thou (0.0005")more for valve.
These can be used for Pre 2012 8 port heads but will need circlip grooves machined in plus shortening where required. See
C-AHT364 for guide with groove and
C-AHT365 for clip as used in our 5 port alloy heads.
Our York Depot is the main contact for anything concerned with 8 port heads