Some valve spring comments.........
Selecting valve springs can get slightly confusing if you havn't done it before , with a little research it's not a big deal.
Some measurments are required to get the best match / results , such as I.D. , O.D. , installed height , seat pressure , pressure when open @ full lift etc.
Comp valvetrain kits for 4.0 engines contain the right springs but NOT the correct retainers or locks , specifically , they need to get with the program , the retainers and locks provided in thier kits are for 4.2 engines which use 3/8" valve stems , 4.0 engines use 5/16" valve stems. Additionally , there are variations on the grooves machined in the valve stems where the locks sit , some are a shouldered groove with a reduced diameter and a single edge or step that the locks rest against . Others have a pair of smooth radiused grooves , similar to what an "O" ring groove may look like , these are known as bead locks , a special order from Comp Cams. Bead locks are also used on LS1 valve stems which by coincidence are also 5/16" stem diameter.
Here's what I do , sit down with a Comp cams catalog , choose springs , retainers & locks based on what is actually needed and will work with the cam being used , while taking care to not choose a spring that is too aggressive.
The latest trend in springs is "beehive" designs , the benefits are , reduced harmonics , the ability to run a less aggresive spring for a given camshaft , less inertia , low weight / reduced diameter retainers , easily clear valve covers when clearances are an issue and more............. Downside of beehive springs is they are a little more expensive , upside ? , I know I'm the only one in the hood that has them.
I recently bought a set of beehive springs to be used in a couple of projects , carefully chosen and ordered as a set of sixteen ( for a V8 ) , twelve of them for a big valve 4.0 head ( to be done later ) the other four will get used in a Harley Davidson / Buell hotrod project . Chosen carfully these will work for both applications , when combined with the correct retainers and locks. The 4.0 head that is on my YJ has Comp springs and genuine Harley Davidson locks & valve seals .
No , I'm not a mad scientist , I just happen to have a bit of an imagination and a handle on how stuff works.