cheers amy. i know so little, i built the fastest proven N/A K10 here.
You know so much that you feel it necessary to interupt and state that all ma12 heads are the same when clearly they are not. Why bother to come out with such a comment when you don't actually know the answer? It just confuses people. I apologise if I caused you offence, there is sometimes misleading information posted here, it just bugs me. We all need to work together as a community to keep things evolving. Anyway which k10 have you built I would be interested to know about it? I thought Pietro currently had the quickest proven k10 Built by Bob?
Bob, out of curiosity did you run both heads at standard compression? Or the same compression? When I was having my heads ported I had both the heads flow tested after they were ported. I don't know what the cfm's were but I was told that the 18b was the one to go with as it flowed slightly better. I know better flow doesn't allways mean more power in reality but it's a fairly reliable indicator.
Raptor, the face of the ports are around the same size, all the manifolds I have seen have the same sized ports, so there would be no gain in enlarging this area, however the port down through the throat and into the bowl is larger. i'm really curious to find out more about this as i'm sure that Nissan would have made these changes for a reason.
The other ma12 head I had ported and ''processed'' was used on Mulbers's otherwise standard car (bar a backbox and 15's) to run his recent 1/4 time, not bad for a car still running the standard carb, manifolds and even air filter. There is a lot to be gained from these heads.
I have a new head on the way from Japan, when it gets here I'll tell you a bit more about it, but until then I'm interested to see more developments.