When you guys shim SBC valve springs how much is OK? Like my installed height is 1.855 but some measured up to 1.875 but some were as little as 1.856. I'm thinking the 1.875 needs shimmed but the closer ones like 1.865 and below will be fine.. is this right? I'm building a fairly radical 13:1 355 roller motor, I'm running 492 heads milled and cc'd @ 60.2cc chambers, ported, flowed, pocketed, 7/16 studs, Elgin stainless valves, Roller springs. I was going to lapp the valves and put everyting together untill I measured the installed height.

Gearhead, this is a common occurence on just about any cylinder head that has seen a valve job. Seat depths can vary, depending on many different factors like you had to grind the seat that much to clean it up. Alot of times, the exhaust valves will vary a little from the intakes by say, .020" . Now, the real question is this, if your springs installed height is supposed to be 1.850", then you have a simple task of just merely putting a .030" shim under the ones that measure 1.875, and you will be at 1.845" and that's good enough. On most competition cylinder heads that I prepare, I try to keep most of the spring installed heights within .015" of one another, and close to the recommneded installed height. Use hardened shims with roller type springs, and you can buy them as thin as .015" to adjust for small variances in installed height. You can fiddle around and get everything just right on the money, but you'll never feel the difference in the seat of your pants. Just don't shim too tight, and run into coil bind problems.

You need to find out what coil bind is, how much lift you have, then subtract lift from installed height. If you have a .100" or more before bind you are okay. Next you need to have springs checked to see if seat pressure is correct. Rollers need around 225# on the seat if it is a solid, if a hyd. then around 140#. If pressure checks out at installed height then you need to use HP shims that are hardened if you don't the springs will eat them.

Cstraub

The cams a Solid Roller with 610-618 lift intake/exhaust 262-272 duration@50 and 110 deg lobe seperation. Springs came out of Canfield heads they are 1.550 and set up for 750 lift I also run Titanium retainers and 10deg Jumbo Locks. Yes I had them checked by my local engine builder. Here's the spece he gave me back: These are double springs with dampners
Spring Load: (lbs)
height-
1.800- 241= LBS
1.750-254
1.700-288
1.650-322
1.600-354
1.550-381
1.500-416
1.450-449
1.400-451
1.350-522
1.300-559
1.250-593
1.200-622
1.150-660

Coil bind- 1.260