LS-3 Valve Springs

[TnBlkC230WZ]

I purchased a set of LS-3 valve springs that I'm installing in my ZZ-4 so I can run 1.6 rockers. The question is, what should I set the install height to?

My confussion is the LS-3 springs allow the bigger valves in the LS motor spin to 6600 RPM with the lighter beehive springs. Should I set them at 93 lbs at the seat or 105 lbs at the seat? I want the engine to spin past 6000 RPM.

The specs are 86 Lbs at 1.8 inch and 105 Lbs at 1.75 inch. The rate is 387 lbs and coil bind is 1.1 inch

The ZZ4 uses a spring with 100 lbs at the seat. The LS-3 uses 90 lbs at the seat

[Mkelcy]

Just a heads up - the LS3 heads use hollow stem intake valves that weigh 89 grams; the ZZ4 uses a solid stem intake valve that weighs 110 grams.

[TnBlkC230WZ]

Just a heads up - the LS3 heads use hollow stem intake valves that weigh 89 grams; the ZZ4 uses a solid stem intake valve that weighs 110 grams.

Ok, so I probably do need to set them with a little more pressure.

[TnBlkC230WZ]

I put the first spring on and didn't realize the ID of the spring was slightly smaller than my spring locator. Compress the spring and a chunk of spring breaks off. At least it didn't fall into the engine.

Now I'm looking for another set of springs. I measured everything and I'm leaning towards Comp Cams 26986 and set them at 1.757 with should gve me about 121 lbs at the seat. My current cam will have .545 lift with 1.6 rockers, but I need to leave room for .586 lift.

Will this work?

26995 Top 1.065 .650
Bottom 1.415 1.000 137 @ 1.700 305 @ 1.100 1.060 280 Lbs

26986 Top 1.065 .650
Bottom 1.415 1.000 109 @ 1.800 284 @ 1.175 1.060 280 Lbs