valve spring mic need help,pic inside
Take a caliper and verify, but on mine, the correct reading is across the true flat top of the mic, measured as if you were to put the mic in a vise or measure it with a vernier caliper. If the retainer is too small and is dropping in the step, try and catch the edge of the retainer with the top of the mic
Your right checked it with a caliper and it read 1.83²° now how did you get that with the numbers on the mic? Also that's telling me I have to shim 20 thousands to bring it to 1.810?
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1.832 ..... The 1 is a given. The 8 is the highest number you can read on the vertical number scale. The 32 comes from the point where the vertical line intersects the rotating barrel. Put it all together and you get 1.832
BUT you should be measuring from the top of the mic to the bottom of the retainer. It looks like the retainer is slightly sitting down in the mic and not squarely on the outer rim. Loosen it up and shift it so the retainer isn't perfectly centered on the mic, more offset. I bet you get a different number
And yes, if you are measuring too big of a number, you would shim to bring the measurement down. DONT measure one cylinder and assume the same shims will work for all the springs. Measure them all before and after the shims have been installed
BUT you should be measuring from the top of the mic to the bottom of the retainer. It looks like the retainer is slightly sitting down in the mic and not squarely on the outer rim. Loosen it up and shift it so the retainer isn't perfectly centered on the mic, more offset. I bet you get a different number
And yes, if you are measuring too big of a number, you would shim to bring the measurement down. DONT measure one cylinder and assume the same shims will work for all the springs. Measure them all before and after the shims have been installed
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Verdad Gallardo 1.832 ..... The 1 is a given. The 8 is the highest number you can read on the vertical number scale. The 32 comes from the point where the vertical line intersects the rotating barrel. Put it all together and you get 1.832
BUT you should be measuring from the top of the mic to the bottom of the retainer. It looks like the retainer is slightly sitting down in the mic and not squarely on the outer rim. Loosen it up and shift it so the retainer isn't perfectly centered on the mic, more offset. I bet you get a different number
And yes, if you are measuring too big of a number, you would shim to bring the measurement down. DONT measure one cylinder and assume the same shims will work for all the springs. Measure them all before and after the shims have been installed
BUT you should be measuring from the top of the mic to the bottom of the retainer. It looks like the retainer is slightly sitting down in the mic and not squarely on the outer rim. Loosen it up and shift it so the retainer isn't perfectly centered on the mic, more offset. I bet you get a different number
And yes, if you are measuring too big of a number, you would shim to bring the measurement down. DONT measure one cylinder and assume the same shims will work for all the springs. Measure them all before and after the shims have been installed
That's up to you how exact you want to be. Do you have access to a valve spring pressure tester? Keep in mind the springs will lose a little pressure once they've seen a few heat cycles.
Tolerance is going to depend on what you are doing with your engine. .005 difference in installed height makes a bigger difference on 600in/lb springs in a 8500 rpm motor, but not so much on 200 in/lb springs in something that only sees 5k rpm.
For what its worth, you aren't given a whole lot of options. Most shims come in .015, .030 and .060 increments. So without altering the valve seat depth you wont have a ton of options. The last heads I setup were all within .005 -.007 of each other and I was OK with that. Theoretically on my springs that would be about 4lb variance in installed seat pressure. Realistically you aren't ever going to get a spring kit out of the box that doesn't have at least that much variance in the springs to start with.
If you have a valve spring pressure tester you can match the lowest pressure springs with the tighter installed heights and the higher pressure springs with the looser tolerance installed heights to help equalize things. This is getting pretty **** though and wouldn't expect anyone to actually do this unless you are building a VERY serious race engine
For what its worth, you aren't given a whole lot of options. Most shims come in .015, .030 and .060 increments. So without altering the valve seat depth you wont have a ton of options. The last heads I setup were all within .005 -.007 of each other and I was OK with that. Theoretically on my springs that would be about 4lb variance in installed seat pressure. Realistically you aren't ever going to get a spring kit out of the box that doesn't have at least that much variance in the springs to start with.
If you have a valve spring pressure tester you can match the lowest pressure springs with the tighter installed heights and the higher pressure springs with the looser tolerance installed heights to help equalize things. This is getting pretty **** though and wouldn't expect anyone to actually do this unless you are building a VERY serious race engine
Last edited by atljar; Jul 17, 2013 at 11:34 PM.
