I just got back my flow numbers for a set of vortec heads with upgraded springs and 1.94, 1.60 (bigger exhaust) ss valves.


sallee chevrolets (sc) numbers for comp:

mine I/E : sc I/E
.100 62.3/53.1 : 58/43
.200 124.5/105.9 : 114/88
.300 178.2/126.4 : 173/125
.400 218.3/ 132.7 : 216/143
.500 225.7/136 : 225/149
.600 221.3/137.5 : 222/152


I was hoping the bigger exhaust valves would help, but I think I might need to do some porting in order to take advantage of them.

Its for a blazer though anyway, so its only going to run at like 4500-5000 max.

 

Well your numbers are very close to the results I got with stock vortec heads on the flow bench.

Yes the exhaust port will need some porting to see the benefit of a larger 1.6 valve. You do not need to make the port exit huge. But the valve bowl and guide boss
can use some opening up and streamlining.

From there, general port cleanup is all that is nessessary.

re-flowtest after porting using a flow pipe attached to the exhaust port. Should be able to get it up to the 180cfm +range easily.

The exhaust port actually responds to general porting techniques more readily than the intake port.
Mostly because it is smaller to start with.

As a note, I got the intake port up to 245cfm @.500" with new 2.02's and moderate but complete general intake porting and cleanup.
The valve job is critical.

 

Which casting vortecs are those?

 

mine are 062's

 

062

the guy who flow benched mine did it with the pipe also and said it was about 4% better than these numbers.