Danlee126

Have had a vinci 210/218 .550/.550 on 116lsa with 1.8 ratio roller rockers for last 4-5 years which makes it around .582 lift. Wanting to switch to TSP 216/220 low lift (.550) or high lift (.600) on 112 for little more chop but retain daily drive-ability.

I guess my questions are...
1 with my 1.8 rocker ratio would I have PTVC issues with high lift and rockers (around .630ish range) heads are milled .030 with stock OEM gaskets
2 does the excessive lift hurt performance since the stock head port maxes at .550ish (that might sound like a dumb question lol but maybe somebody will understand or explain what I'm trying to ask)
3 If PTVC is fine with high lift and 1.8 ratio rockers would you go with that on stock heads? I know in duration world on little 5.3 bigger is not better, however with lift options on low verse high wondering which one to pull the trigger on.

madmann26

iTrader: (7)

PTV issues come in to play with larger duration cams.

Duration = how long the valve is hung open.

I wouldn't worry about it. I had a cam that was over .600 lift in my old 5.3. It ran fine amd no issues.

However, it's always best to measure.

MikeGyver

iTrader: (5)

2. You want a cam to lift the valve past the point that the port flows the max so that the valve spends more time at that point. Opening the valve more won't reduce flow, it just adds extra time that the valve is open without necessarily adding more duration. A valve only has too much lift if it hits the piston or the springs aren't rated for that lift.

Vortec350ss

iTrader: (20)

You have a long way to go before its detrimental to the parts, however, on a stock head nothing over .600 is worth it. I would say with .582 youre kind of in the sweet spot. Much more than that and the added power it takes to compress those springs down is more than you gain. They stop flowing more air at about the lift you have.

with a high quality CNC job that game changes....