Big Woo
DSM Wiseman
- 458
- 19
- Sep 9, 2002
-
Grand Rapids,
Michigan
Some things to consider when porting the exhaust side, and flow bench testing a head.
1: Flow bench testing should be done with the valve seat work done (I.E. a completed valve job, be it a standard grind, ar a five angle) One of the more critical elements of port flow is how well the air flows around the seat and valve. Try comparing a stock head with a fresh standard valve grind, and the same head with a five angle valve grind. If you are interested in doing the testing, I will make my shop available for the machine work on the cylinder heads.
2: generally a dial indicator is used to measure valve lift while testing, while a bar and screw assembly is typical for valve adjustment.
3: I have found that when porting the exhaust side a radius under the valve seat area will improve flow. Think of it as a venturi between the valve seat and the exhaust port. Of course it is difficult to hand port a concentric radius, and repete it seven more times to complete a single 4G63 head, so this procedure is useually done on a machine (CNC, seat & guide machine, vertical mill etc.)
Well let me know it you are interested in doing some testing, and I do have a cylinder head that could be used for the testing.
1: Flow bench testing should be done with the valve seat work done (I.E. a completed valve job, be it a standard grind, ar a five angle) One of the more critical elements of port flow is how well the air flows around the seat and valve. Try comparing a stock head with a fresh standard valve grind, and the same head with a five angle valve grind. If you are interested in doing the testing, I will make my shop available for the machine work on the cylinder heads.
2: generally a dial indicator is used to measure valve lift while testing, while a bar and screw assembly is typical for valve adjustment.
3: I have found that when porting the exhaust side a radius under the valve seat area will improve flow. Think of it as a venturi between the valve seat and the exhaust port. Of course it is difficult to hand port a concentric radius, and repete it seven more times to complete a single 4G63 head, so this procedure is useually done on a machine (CNC, seat & guide machine, vertical mill etc.)
Well let me know it you are interested in doing some testing, and I do have a cylinder head that could be used for the testing.