I have 2 set of cam followers for my 1098 engine. One lot have drain holes and the other lot don't. Does anyone know why and which are the better version?
They eliminated the drain holes in the later ones - just a cost saver I think. If the ones with drains are in good order I would use them - helps to lubricate the cam lobes. However - don't use any with 'pits' or 'crazing' - they must be smooth and even however slight rub marks are ok.
It should be off to the side - and is almost essential for good follower lubrication if using high lift cam with heavy springs. Some make a flat down the side of the follower as an alternative route for the oil - but I don't fancy that!
Just found the information I thought i'd read. It comes from a David Vizard book, and his opinion is that the hole does not appear to prolong the life of the follower and if you have the choice use the undrilled ones, as plenty of oil get around the follower without the hole! In fact the more tuned the less desirable this hole becomes. It seems this guy has a pretty extensive knowledge of the A series.
Thanks Les, for the trundling I have in mind I think the drilled ones will be ok, the solid ones have wear marks on the face, I don't want to use them if I can help it.
I would say that's the case with performance high lift cams/heavy valve springs - but for a standard set-up as long as the followers pass a close inspection with no pits or crazing - they will be fine.