Paulyy

This got covered so new question


Why does the valve springs need to be 41 +.5mm?

When i took the valve spring shims out, they're where all over the place, 3 in 1, 1 here or there and 2 everywhere else. (doesn't make sense to me)

I just did this for the intake valves for the time being.. I put the intake valve back in and put the top retainer in with the clips, I worked out the distance from the bottom of the retainer to the surface the cam tower sits on.. (lets call the distance a). Then i got a depth gauge and measured from the surface where the cam tower sits on to the surface where the shim sits on and got the distance b
Lets add the thickness of the retainer: c

Now when i did the math (pretty simple)
a+b+c = spring height (x) am i right?
or am i suppose to subtract the retainers (c) and we'll call the bottom one d?

Because when i did this for all 4 intake valves, they all added up the same heights. IICR they where all 45mm from the tip of the spring retainers to the bottom of the spring retainers.
Thus needing 4mm shims which doesn't seem right.

xsboost90

when you pull the valve spring retainers and pull the springs out, there are seats under the springs- under the seats are shims. There is a standard height for the spring assy and the shims make them all the same, so some have shims and some do not....some have two.

Paulyy

Thanks for that, i found them.
do you know the standard height for the springs?

xsboost90

hmmm no my machine shop guy knows...i could prob. look in the manual real quick.

Paulyy

If you could, that'll be great, because i've got shims all over the place, some have 1 some have 3. not sure if they've been mixed and matched or what.

Paulyy

Thanks, i found it also.

Paulyy

New questions on original post

Thom

Adjusting valve springs as described in the FSM assumes that all springs have the same stiffness, which can be incorrect.

A better method is to figure out the developed stiffness of one spring as installed with the required height then adjust the heights for all other valve springs so that they return the same developed stiffness as the first spring. By doing so you balance out the effort required to open all valves.

Paulyy

So i should get the stiffness of all the springs and set the height to make the stiffness all equal? and not worry about the springs all being 41mm high?

Thom

Yes, but make sure you don't end up with installed heights that are "too" remote from the two values mentioned in the FSM. You have to decide after measuring each spring which one is going to be your "average", or "benchmark".

Paulyy

Thanks, makes heaps of sense.

Tedro951

Like Thom said. A shop can check the pressure at installed height for cheap. Then you can "adjust" the installed height to match the pressures, but any spring that is too far out of bounds should just be replaced. Too much adjustment will lead to other problems.

In other words, the springs should be real close in pressure, anyway. I'd stick to using the shims for installed height.

Paulyy

okay, i'll check the springs, and i'll install them at their height.
by the looks of things, every intake spring will have the same shim and so will the exhaust valves.

Tiger03447

Your machine shop guy should have a pressure gauge that compresses the spring to check the spring pressure. They should all be pretty consistant across the board. He can also help you sort the shims out also, but he'll have to have the head so he can measure the heights...jus sayin...

Tiger03447

Btw, most shims look like a thin washer...and the thickness may vary. Depends on how the head was machined initially..