k i have stock ported iron heads...i bought a roller cam kit that came with the new beehive springs...now im wondering if anyone has ever needed to use any shim under that spring (918 ones)??? or have you just set it all up and dropped the valve springs right on with no adjustment needed???...thanks for help...noah.
Engine builders...has anyone ever put any shims under your springs???
- Thread starter noahzark
- Start date
- Joined
- May 28, 2001
The installed hts need to be measured, to determine if shims are needed. The spring pkge should have an installed ht called out.
Several things dictate the need for shims:
1. Valve seat location. [Sunk, due to too much valve grinding.]
2. Valve stem length. [Used valves that are stretched, etc.]
3. Type of retainer/keepers used.
4. Spring locator cup thickness. [Beehives do not locate off the guides.]
5. Cam lift has to be considered, to ascertain a satisfactory guide to retainer/seal clearance.
6. Springs have to checked for coilbind, at max lift. [Too much shim, and this can occur.]
Bottom line: No, it's not a drop in and go deal....
Several things dictate the need for shims:
1. Valve seat location. [Sunk, due to too much valve grinding.]
2. Valve stem length. [Used valves that are stretched, etc.]
3. Type of retainer/keepers used.
4. Spring locator cup thickness. [Beehives do not locate off the guides.]
5. Cam lift has to be considered, to ascertain a satisfactory guide to retainer/seal clearance.
6. Springs have to checked for coilbind, at max lift. [Too much shim, and this can occur.]
Bottom line: No, it's not a drop in and go deal....
XXQUICK6XX
Well-Known Member
- Joined
- May 24, 2001
Valve spring shims
Yes. But as Chuck said I had my guides cut for spring cups. Then added shims to gut the correct installed height.
Yes. But as Chuck said I had my guides cut for spring cups. Then added shims to gut the correct installed height.
Should one add shims to :
1) achieve a specified height, OR
2) achieve uniform pressure in all valves, which might mean slight variations in height from one valve spring to the next.
I would have thought #2 is more "correct" and fundamental to engine performance & longevity ... yes ???
1) achieve a specified height, OR
2) achieve uniform pressure in all valves, which might mean slight variations in height from one valve spring to the next.
I would have thought #2 is more "correct" and fundamental to engine performance & longevity ... yes ???
Due to normal manufacturing variations, even new springs would have several Lbs difference at the same installed height ... so should a total range of, say, 5-7 lbs across a set of 12 new springs be ignored?
And just set them all at same height? (Comp Cams sells copper shims for this purpose)
And just set them all at same height? (Comp Cams sells copper shims for this purpose)
A few lbs of valve spring difference isnt too bad. The thing is the installed valve height is whats going to affect your volumetric effiecency the most. IE correct valve height will makes sure all your valves will open and flow the same amount with what ever cam you are using. If you use the shims to increase spring tension, then your valve will actually open up less and you will have less air flowing into that cylinder. Comp Cams might include specs as to what your valve springs should be (lbs) at what installed height and at what compressed height. Notice they always tell you the installed height they recommend and not the spring pressure (lbs) they want at a certain height.
blown okie
Chuck Norris Approved
- Joined
- Apr 28, 2005
your dumb, please never, ever set-up any heads or valve-train, you do not know as much about this as you think, and you are only going to confuse this guy more. and yes i do know what I'M talking about i build racing engines for a living, and i would elaborate on the subject some but the first couple of posts pretty much covered it.
Okay,..... and your a idiot! So whats your point!?
