The V8 Owners Forum -

Admin reminded me I haven't been on here for a long time and as it happens I do have a problem right now. I have a set of double valve springs for our 4.6 I want to fit but not sure what the installed height should be. They are after market springs but I don't know which brand, It seems that most after market spring suppliers say fitted height 1.54'' the Land Rover manual I have says 1.6'' So does the difference of .060'' thou matter. If I end up with the fitted height some where between these figures it will be fine, right ?

installed height will determine two things.

Actual spring pressure available both closed and open, and also depending on valve lift, how far you then are from coil bind at maximum lift. Which will of course also depend on what lift you actually have.

I would say there are some generic notions, that go along the lines of springs should be run to about 1mm from coil bind at max lift to get the best from them.
So you'd need to measure where coil bind occurs, then work back and shim the spring platforms to achieve that compressed height at max lift.

Or just wing it and install them whatever way they go in

As stated above, there are many facets to determine vakve installed height. are you running sokid or hydralic flat tappets? or maybe hydraulic or solid roller cams. As the Rover engine grows a large amount due to expansion from cold to hot this must always be conisdered along with anticipated red line. I have set valve clearance cold at 0.008" and then observed 0.025" when the engine is hot.

The installed height of the valve spring is usually limited by the camshaft lift, the rocker ratio and the ability to use full lift with a clearance of 0.060" from coil bind. This an instance where more is not better, excessive clearance betweeh the coils at full lift encourages valve surge and float. Neither is a good thing in a short height spring.

Thanks for your replies. It seems from what has been said that I should assemble the valve springs with no shims, then fit heads using solid tappets and adjustable pushrods. Adjust pushrod to take out any slack then measure clearance between coils on each spring with cam on full lift. Then shim springs to end up with gap between coils of at least 1mm. Sound like a lot of fun.

larryowner wrote: ↑Tue Jul 16, 2024 9:32 pm Thanks for your replies. It seems from what has been said that I should assemble the valve springs with no shims, then fit heads using solid tappets and adjustable pushrods. Adjust pushrod to take out any slack then measure clearance between coils on each spring with cam on full lift. Then shim springs to end up with gap between coils of at least 1mm. Sound like a lot of fun.

No.

You know your cam's lift, you know any rocker ratio. So you know what the final valve lift will be. Measure, shim to suit, job done