spring shims?

[wed3k]

anyone ever thought about installing shims under the spring to increase seat pressure?

the valve springs are fairly long and i highly doubt that a stock or a regrind will have all that much lift so coil bind may not be a problem.

another 10lbs to the seat would be kinda nice
ill check it out 2morrow though.

[bjaccord]

Domestic guys do it all the time so I don't see a reason why not. They use shims to adjust seat pressure as well. Go for it and let us know how it works. L8r

[wed3k]

i measured stock seat pressure at 45lbs @ 1.820"

.060" shim = 55lbs @ 1.760"

with a .410 lift = 135lbs @ 1.300"

coil bind at ~1.100"
im using a VSI 104 and it is sandwiched between the seat cup and spring.
pics later.

[KeeleDesign]

is this a tricky way of letting the springs do more work without having to upgrade to a dual spring setup?

i duno why domestic guys would do this.. not saying they don't, but all my friends..
there motor builds consist of triple valve springs.. and still occasionally break some of them

[preludeman92]

is this a tricky way of letting the springs do more work without having to upgrade to a dual spring setup?

i duno why domestic guys would do this.. not saying they don't, but all my friends..
there motor builds consist of triple valve springs.. and still occasionally break some of them

Remember though that domestic motors can run huge cams...
5 mintues of summitracing let me find a cam for an LS1 that had .605"/.609" lift. That's not the half of it. Almost litterally. They also run rocker arms with some huge ratios... a 1.8:1 is a quick look into what you can find for an LS1.
That means the valve lift on an LS1 is somewhere in the neighborhood of 1.089" if I get everything. I don't think that's even possible on a honda.

If you get something recipricating that much as 4-5k times/minute (yes, an 8000 rpm LS1/pushrod motor is not hard to accomplish) and shit starts to break, even with the tripple valve springs you see on some dommestic motors. I'd be interested in trying valve spring shims. I'd still worry about coil bind with the cams I want to run though.

[KeeleDesign]

Remember though that domestic motors can run huge cams...
5 mintues of summitracing let me find a cam for an LS1 that had .605"/.609" lift. That's not the half of it. Almost litterally. They also run rocker arms with some huge ratios... a 1.8:1 is a quick look into what you can find for an LS1.
That means the valve lift on an LS1 is somewhere in the neighborhood of 1.089" if I get everything. I don't think that's even possible on a honda.

If you get something recipricating that much as 4-5k times/minute (yes, an 8000 rpm LS1/pushrod motor is not hard to accomplish) and shit starts to break, even with the tripple valve springs you see on some dommestic motors. I'd be interested in trying valve spring shims. I'd still worry about coil bind with the cams I want to run though.

i see what your saying but i am not to familiar with building the heads a whole whole lot.. i undertand that the coil bind could be less of a worry if you were to just uprade to dual valve springs instead of shims.. correct?

what exzactly holds them in place ? especially on a 8,000 rpm reving motor compared to the 5200 reving ls1

[preludeman92]

Remember, cams spin at 1/2 crank RPM (which is the RPM we all talk about), so your h22 spinning at 8000 rpm has cams that spin at 4000.

Shimming the springs makes them shorter. Bigger cams on shorter springs means more chance for coil bind. Dual springs are the same height, but stiffer, meaning you don't have to worry about bottoming out the springs.

Wek, get more measurements... you have me interested, but the cams I'm getting have .430" lift, so that's right at the coil bind limit.

[wed3k]

Remember, cams spin at 1/2 crank RPM (which is the RPM we all talk about), so your h22 spinning at 8000 rpm has cams that spin at 4000.

Shimming the springs makes them shorter. Bigger cams on shorter springs means more chance for coil bind. Dual springs are the same height, but stiffer, meaning you don't have to worry about bottoming out the springs.

Wek, get more measurements... you have me interested, but the cams I'm getting have .430" lift, so that's right at the coil bind limit.

you'd still have .180" to go

[preludeman92]

Ooops. My bad. I did mental math wrong. Anyclue what the coil bind for an h23 is?

[wed3k]

Ooops. My bad. I did mental math wrong. Anyclue what the coil bind for an h23 is?

id have to check that out on monday

pics on first post.

[SteveB]

i see what your saying but i am not to familiar with building the heads a whole whole lot.. i undertand that the coil bind could be less of a worry if you were to just uprade to dual valve springs instead of shims.. correct?

what exzactly holds them in place ? especially on a 8,000 rpm reving motor compared to the 5200 reving ls1

The spring holds them in place.

Spring shims are used to make up for any lengthening of the spring due to the valves seats being cut, (thus lenthening the distances from the spring seat to the keeper) and to make sure all the installed heights are the same.

[wed3k]

The spring holds them in place.

Spring shims are used to make up for any lengthening of the spring due to the valves seats being cut, (thus lenthening the distances from the spring seat to the keeper) and to make sure all the installed heights are the same.

bingo

[wed3k]

h23 coil bind is right at 25mm.