what effect would more lift have between two similar cams ? ex. 228/230 .571/.573 compared to 228/230 .581/.588 both 112+2 ? or would the differences be negligible ?....thanx

 

same car, same mods, same heads, i think the .581 one would dyno a tad higher, . . jus a tad

 

car has TSP 5.3 heads, longtubes bolt-ons etc....

 

Depends on your heads, for the most part. If the increase in lift took the valve to a point where the port stalls or backs up, then you could potentially lose power.

However, .010 - .015 more lift would probably never net a measurable difference. I think you need .030 - .050 more to see a real difference with all other things being equal.

 

these are my heads with 2.04/1.575 valves

 

goin bigger this winter, but the larger valve sizes cut into my PTV clearance so i'm tryin to keep duration and lift in check...thnax for the reply

 

The duration will make a bigger difference in PTV clearance than an extra .010 - .015 lift would. It pays to check clearance so that you know you're safe. If you already have the heads installed, you could still check with a dial indicator and some checking springs to be sure you'll clear.

It looks like the flow continues to improve up to (and perhaps even beyond) .600 lift. Consider notching the pistons if need be. The extra lift is more time spent in higher flowing portions of that graph, giving you the potential to make more power.

 

cool, thanx for the help

 

LIFT has nothing to do with PTV as max lift occurs close to BDC and not TDC.
Durations and Valve Events (LSA/Advance) is what you should look at.