Another day, another speculative Ebay purchase. I found a cheap 916 gtv Busso block on Ebay, minus it's sump, conrods, crankshaft, liners, etc. The chrome trumpets looked in pretty good condition (except for one small dent) and I thought I could do a quick comparison between the 12v and 24v blocks before I binned the rest, so thought 'why not'?
When I went to pick them up it turns out the block isn't the sad remains of catastrophic bottom end failure, it's actually a near-immaculate low mileage block which has been used for speccing and measuring by an engineering shop who supplied parts for EBSpares
So if anyone needs a very nice 24v 3.0 block or heads, drop me a PM
But without further ado, down to the comparison...
Firstly, the really, really interesting bit. Looking at the casting for the 24v pump vs the 12v pump, you can see there are small differences in the cavity size, but the waterways and bolt holes match perfectly.
And sure enough, a 12v pump fits into the space rather nicely, and spins freely when bolted down.
Following through, I could see no discernible difference between the 12v and 24v heads' or blocks' waterways.
And even more interesting, it looks like it'd be a simple job to remove the core plugs from the front of the 24v heads and block off the waterway at the rear end, to make it suitable for a front-mounted stat.
Rest of block is extremely similar (24v would have an extra bit bolted on to hold the oil filter, though presumably the housing could easily be tapped to accept the older type oil filter if necessary). So, could it be, after all these years of commonly held wisdom, that the more modern 24v can easily be converted to have it's stat and housing at the cambelt side of the engine? However, there is one fly in the ointment - spot the difference:
Damn. Though the bracket at the bottom could easily be modified to take an early 164 24v's pump, the casting the pump shaft would need to run through has been removed.
The common way around this is either to modify a 75 sump to fit around the later 916-style oil pump, or to dry sump it. And I don't have the skill / expertise to do either of those, so sadly, despite it's lovely condition, this block's no use to me. I won't have any use for the 24v heads either, since they're lacking the necessary casting too.