Cylinder Heads 101

6t8 Dart,
The 308 heads have a small window opening because of the big hole for the pushrod, and a larger bowl area. The larger bowl area is where the flow comes from, but this is very misleading as the bigger the bowl gets the slower the velocity will get even though the head will flow more air with a larger bowl. This is the same thing that Indy cyl.heads had done with the 440-1s, with these heads on a 446 engine you would have to turn the engine up to 8000 rpms to make them work. The 308s don't really flow that much better than that of the older counterparts when done properly. For the street engine that your talking about I would just do a bowl cut with a 75R7 cutter and leave about .060 before the valve seat for a additional angle to be put in of your choice. I would square deck the block a minimum amount and deck the heads a minimum amount, then run the .022 gasket from mopar, this should give you your 9.0-9.25:1 compression ratio. Most blocks will take .015-.020 to clean them up just as the heads will, just this difference will increase your compression ratio about 1 point and as the 360s were 8.5:1 or so from the factory this should put you where you want.
Then I would use a .484 from mopar or equiviliant cam, this may not sound like much but the difference is in the duration @ .050, and if you want a mech. cam the use the mopar .528 or equiviliant from who ever. But keep your centerlines and duration @ .050 similar or the driveability will be lost.
How much converter will you be running? If your not going to a stall converter then the .528 is out. As this cam will need at least a 3000 stall. Then I would use the .484 cam profile with a stock converter as the duration at .050 is a good bit less and more compatiable with the lesser converter.
Hope this helps you in your decisions.



BJR Racing