The valves and guides we stock - Indian clone parts. As in everything else we handle, the specification was given to match OEM parts interchange 100%. Of course, there is often no way of proving this short of ordering and comparing the actual parts. In most cases also doing assembly and testing with them in real service. It has been my experience that most of the complaints and issues come along with Indian reverse engineering that fails to match the original parts specs... there is no way anyone can claim that all Indian parts are bad because they happen to have experienced such issues before. We are happy with our suppliers overall... I hope we are able to remain so. The Indian parts do require an extra level of care and attention to detail during fitting that many old Lister mechanics and most modern engine mechanics are not used to dealing with. It is nice to be able to assemble well-known parts with well-known and reliable specifications, but we are faced with less than ideal circumstances in this day and time.
valve stem diameter 0.43"
exhaust guide body o.d. 0.74"
exhaust guide overall length 4.29"
exhaust guide machined interface length with head 1.76"
exhaust guide stem counterbore depth 0.58"
inlet guide body o.d. 0.74"
inlet guide overall length 3.48"
inlet guide machined interface length 1.53"
These guides fit the valve stems perfectly
Apparently the heads you have sourced are something off-spec... where did they originate? What supplier? It may be best to go back to that same supplier and complain about the poor fit and off-spec dimensions/designs. They may have the proper replacement parts for their stuff as well. We hope!
dieselgman