math class needed on valve springs

[gsa612]

The Pac 1220X spring shows 160 lbs seat press.at 1.900 and 400 lbs open at 1.250 which is close to coil bind.If you subtract your lift of .450 from the 1.900 your at 1.450 open.That may give you only 360lbs press.You need to find a "short" spring with your low lift that will give you the open pressure your looking for.Even if you do find a long spring that gives you the numbers, but is .300+ from coil bind your going to have valve stability issues. Have you looked into Comp cams ?. gsa612

[FireSale]

What's the application here? It doesn't really make sense to talk pressures when we don't know what is being asked of the engine. I run PAC 1427 springs - conical for a BBC - in a SBF with NASCAR type iron heads. Stuff gets mixed up when all you want is GO...


Note: A PAC 1409x at 1.8 will give you pressures of 175/384. I'd give up on a 1.78 IS, it's too hard to shim to. 1.8 or 1.85 are common.


Note 2: What is the seat size?


Ask questions and give info. I didn't so I have 4 sets of springs now............