You are pretty close on the 848 head. They are spec'd at 79.1 but I have never had one actually come in at that number. The heads that i have cc'd have been like 81 82cc. My 261 heads are different castings with one spec'd for 86 cc and the other at 95 cc. If I was a betting man I would bet if i actually cc'd them both would be bigger. There is just no way I can build a 261 with stock pistons sitting so far down the hole. I have one 261 going together with gmc rods and venolia pop up pistons. Having trouble with the pop ups hitting the head. In the process of making a combustion chamber mold for venolia so they can see what the problem is. The second 261, which is the back for the first I wanted to do the 292 rod with cad pistons but the pistons appear to be very hard to come by now. So I was sort back to a 261 rod motor but could jot for the life of me come up with a substitute higher performance off the shelf piston instead of the stock 261 pistons. No luck. I will have to start saving my pennies. Want a little snap, not just dump truck performance
