Trying to identify the cylinder heads on my small-block '78 Z. The last three numbers are 260. Neither I nor anyone I know has ever heard of this number. Almost nothing on this car is original, and I doubt any part of the motor came with the car. I didn't build the motor, but I have had the intake off for a cam change, and the intake ports seem very large, and the car responded very well to the bigger cam. Anybody heard of this number?

These heads use the big spark plugs, 13/16 inch socket with metal ring gaskets, or the small 5/8 inch socket plugs? That's a starting point to ID the heads.

These heads use the small 5/8 plugs. R43t I think. I neglected to mention that the compression must be pretty high, since no amount of timing voodoo wwill make it run on regular gas. I would suspect the heads might be 305 pieces, but it runs perfectly on premium fuel. (no ping) Now that I've said it, I wonder if I've ever had a motor that ran perfectly. Probably not. Thanks for the help.