Sootysevener Posted November 7, 2006 Share Posted November 7, 2006 Just drawing up my letter to Santa and the prospect of a Vulcan Ally head springs to mind. Anyone got one? - whats it like in performance terms? Any issues with warping? returning to UK next year and will need to go unleaded anyway then so the need for headwork is clear - or should I save me pennies and have the existing head rebuilt with hardened exhaust valve seats David 1989 1700XF SS clams with carbon webshots here Link to comment Share on other sites More sharing options...
Leadership Team Mcalvert Posted November 7, 2006 Leadership Team Share Posted November 7, 2006 I have had one for the past couple of years. My reason for changing is that I have fairly large valves and twice previously suffered cracks between inlet & exhaust ports of a standard head. The ally head is better designed to prevent this problem, and so far so good. I know that you can go fairly crazy on valve sizes on the ally head but I am sure at the expense of reliability. There's a serious weight saving too... Michael. Link to comment Share on other sites More sharing options...
Peter T Posted November 7, 2006 Share Posted November 7, 2006 The main reason for cracking between valve seats on large x-flows is because of the hardened valve seats that are usedfor unleaded conversions. I have seen lots of full race heads that are not fitted with un leaded seats and suffer not. It seems that the valve seat causes varying heat dispertion around the chaber which causes the cracking of the head. Matching correct properties of the valve material and seat has an impact of reducing this problem. R500 Mango Madness Link to comment Share on other sites More sharing options...
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