How does this actually work in minis, what happens to the old cam? Is it still an A-series engine block? Thanks

yes, the old mini cam shaft stays there as it still drives the oil pump & distributor (if you use one)

Yes the original A series block is used & just some mods needed to it so the cyl head fits on,,, then add all the drive gear for the cams etc & Bob`s your Aunty

Turbo Inject it & you have more pull than a bunch of school boys

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.