I am not a professional pattern maker, though i have made professional patterns and core boxes.
(Pro= they made commercial products cast in multiples that sold reasonably well. In one case, they would still be selling except my last foundry went out of business and the patterns were stolen or destroyed. The parts were large and the margins low, i have not been inspired to make new patterns, and the "competition" has caught up selling similar models.
Starting with that "qualification" I only see 2 cores so far, depending how the finning works out to orient the combustion chamber in relation to the parting line. I "imagine" there will be another, or couple more, cores for the pushrod channel once that is worked in, so if you were including that; then "yes". OTOH I'm assuming shell cores, not paste-up. Modern foundries don't want to work with paste-up cores, and the cost per casting is an impressive factor higher cost. Shell cores will also give very smooth dimensionally uniform, essentially "lost wax" surfaces, say, in the induction and exhaust ports.
Looking harder at your drawing, i'd almost go out on a limb and suggest one shell core could do the whole negative space.
They do shrink and can slightly tear coming out of the shell core box, so overall dimensions and locational tolerance could be a factor. As would, again, the finning and parting line(s) to determine available geometry to position the core prints in the pattern. (IOW, it could be possible to blow the entire core as a unit in 3D space. However, if the points where "the ends" must fit to the 3d space of the primary pattern don't admit (nearly) parallel entry, then one or the other might have to have to be broken down into smaller interlocking components).
I don't assume i'm telling you anything new, but there may be others following along.
smt
