How Valve springs are checked

[BogusSVO]

How Valve springs are checked


I had to check the valve springs for a 4G63T


This is a simple process. But a specialized piece of equipment is needed.

I use a Rimac spring tester with a 300lbs scale.

The first thing to do is set the stop to the correct height.
The spec used is 66lbs @ 1.575
I find that a venier caliper is more accurate than the built in scale.


Place the spring to be tested in the spring tester




Compress the spring to the pre set height and read the pressure.



It is a quick and simple way to have your valve springs checked to make sure they are in good serviceable shape.

Low spring tensions can lead to a lazy rev of your engine and also valve float.

Most of the valve springs I tested I found to be well out of a usable spec.
Most springs I tested fell in the range of 40-55lbs @1.575
Most spring manufactures allow for 10% loss of spring pressure for spring break in.

[blkfordsedan]

I have one of these testers at home (an old one), along with a selection of shims. Even if the spring pressures test out good, we always try to get a consistent pressure across all valves (via shims) as a form of redneck blueprinting.

Like you stated, the installed height is the key. We always measure the actual installed height from spring seat to bottom of the retainer on each valve, especially if new valves/seats have been installed.

[BogusSVO]

Blk... the use of shims is not redneck blueprinting.

Shims see common use in setting spring tention, and will almost be used in any used head casting, valve and spring set up.

I use shims when setting up new springs.

Shims come in .060, .030 and .015 thicknesses

[blkfordsedan]

Sorry, by redneck I mean one of the simple techniques....doesn't make it bad. Just attention to detail that can be done without spending a bunch of money.

[BogusSVO]

Lol... you should see the selection of shims I have!!

[Bert]

Post well worthy of a sticky.
Speaking of which what are new springs worth? Spring steel does fatigue and/or get lazy over time and our cars are not 'spring chickens' anymore (pun intended). Back in the dark ages you could buy performance inner and outer valve spring kits which raised the incidence of floating valves by another 1000 rpm instantly. Is such a thing possible with Festys? May be not good for an ordinary engine but a necessity if you start toying with cams and air intakes.

[blkfordsedan]

Stock springs are more than adaquate for lobe profiles of a stock cam....and will run waaay past the rpm limit where thes motors run out of power. Any more spring and you only increase wear and valvetrain stress. That said, new stock replacement springs are not a bad investment. If you have a FMS cam, I'm told the stock springs will be fine as well...although we have never received a spring seat pressure recommendation from FMS, so who knows...