Valve Springs

[NE57]

The heads that came with my 392 had already been set up. I have the reciept from the machine shop which names the springs as Crane #99893. Crane's website is down(they went out of business?) but Jegs catalog lists a crane spring with this same number plus a prefix which is probably a jegs in-house number. If this is correct these springs are rated at 120# closed(@1.875") and 426# open(@1.110"), coil bind @ 1.080'', max lift .690

The previous owner was building a blown engine until he quit the project after doing the heads only. Intake valves are 2.125" ex is 1.945" Anyway these are the heads I have to work with. My question is are these springs suitable? To me sounds like pretty beefy spring rates, maybe too much? I don't know the pressure at whatever open height I'll wind up with but certainly will be less than the full rated spring pressure just before coil bind. Just guessing here but maybe the actual installed open pressure will be around 300-325 lbs?

Another guess I make is that these bigger heavier valves indeed require some extra spring pressure over what might be normally called for depending on cam. But how much is too much for a hot street motor that probably won't see 6000 rpm often if at all? (6000 is at this point somewhat arbitrary, I don't really know the rpm potential of this thing yet)

I'm going to take these heads apart anyway, just to satify myself on what's what(they've been sitting for 4 years). At the very least i think the stems need reoiling. I can check installed spring heights if that helps figure out the situation.

So, guidance and advice on spring rates etc would be appreciated. I want it hot, streetable, but I want it to last, too. Thanks much.

[DblAdigger]

Spring pressure required to do the job...for you, should be, initially, determined by the cam grinder. Consider that a starting point.

[budmspeeco]

Check the Summit info on the springs and get the listed spring rate, the pressure the springs go up in 1". If you cam has .500 lift, divide that spring rate by 2 and add the new amount to the original seat pressure. . Or you can figure the spring rate from the info you have now. Springs are 120# @ 1.875 and 426#@1.110. That makes the spring rate 306# for .765 " of lift. Divide 306# by .765" and the spring rate is 400#/inch. If you have a .500 lift cam the open pressure will be original seat pressure120# + 200# or 320# open. I am surprised to see that length of spring height unless the machinist put in longer valves that Hot Heads and others sell. The main reason is because I think I read the original assembled height of a hemi head is only in the 1.650 range. We have all read it is better to put bigger springs on hemi heads as long as the diameter and not depth is used, unless going to longer valves/assembled heights. The spring seat area on hemi heads is thin and cannot be sunk much without going through to water. 120# on the seat is about right for a hydraulic cam ,a bit low for a solid. 320# is a tiny bit stiff but not out of the question since you have some big heavy valves to open and close and as well as stopping those long hemi pushrods AND still keep valve float under control. Check with your cam mfg. and he will be able to give you all this info to make an educated choice. Just make sure the cam is thoroughly covered with cam lube as well as the lifter bottoms. Prelube the engine before startup and keep it over 2000 RPM for the first 25-30 minutes so the cam will properly break in. Have water in the radiator and the timing,lifters/push rods/rockers set,carb filled with fuel so you don't take too long to start or have to shut it off too soon !! You may want to put in some of the recommended additives since oil no longer has zinc in it. The cam and lifters will love you for it. Just my 2 pennies worth. Buddy

[budmspeeco]

I forgot to add I looked the springs up in my Crane catalog. They are listed as being for flat tappet or hydraulic with a recommended seat pressure of 120 @ 1.875.. They don't give spring rates but calculating it with the same method & their info gave 391#/inch. They should work fine. The only thing you need to verify is that each spring is at the recommended height with /without shims. If the length is too long shim them, too short you will have to resort to retainers or keepers that adjust/lengthen the height up to the 1.875 . I am now up to 4 cents. Buddy

[NE57]

Buddy,
interesting, interesting. Supposedly the machine shop that set up these heads is locally reputable, but that's a few hundreds miles from me so not local to me, I have only the sellers word, that's why I'm checking.

Ok valve lengths...I'll check them but where exactly do you measure valve length? Is it the actual stem only up to the flare behind the valve head or is it the total length of the valve sitting on a bench?
Thanks!

[budmspeeco]

At this point the valve length is not the most important thing to worry about. If you just want to measure them it is the total length from the tip to the top of the head. The assembled height, the distance from the bottom of the retainer to the spring seat is what you need to check. It should be 1.875+/- .015. The spring seat pressure is determined by this dimension. I always go to the exact amount if possible with the use of .015,.030, and .060 shims. I go .010 over rather than .005 short because the springs will drop a little after being in service. I actually check the height at the recommended pressure and set them to that rather than the numbers on the card. I have a spring tester for that. Any machine shop in your area should be able to set them for you. If you have to do it yourself just go with the 1.875. You also need to check the distance from the bottom of the retainer to the top of the guide/seal. Put an intake and exhaust valve in the head and install the retainer and keepers on top. Hold a light pressure under the retainer with two fingers and tap the top of the valve tip with a small hammer .It sets the keepers in the retainer for a more accurate measurement. If this is less than the lift +.050 the guide needs to be cut down. It's VERY critical that you don't bottom the retainer on the top of the guide. Check every valve and guide for ALL of these measurements. You can/will bend your pushrods, bend valves, break the rockers, or worse even ruin the cam/lifters. I hate to bring gloom and doom to you, just want you to get it right. Now that that is done you will have to get a correct length pushrod. Buy one of the kits to check it and get a set the correct length that you can adjust. Hot Heads can help there. Just be sure to get a set that has a compatible tip for your rockers and lifters. They could be 1/4, 5/16th, or 3/8th. Up to 6 cents! Buddy

[George]

Crane is Tango Uniform. Wal-Mart sells "Accel" brand 10W-40 SF oil, it has zinc, as does thier house brand 15W-40 CI-4 Diesel. Seen CI-4 Coastal brand @ AutoZone recently.

[mart]

Crane is Tango Uniform. Wal-Mart
sells "Accel" brand 10W-40 SF oil, it has zinc, as does
thier house brand 15W-40 CI-4 Diesel. Seen CI-4
Coastal brand @ AutoZone recently.

====================================

Shell "Rotella" heavy-duty diesel motor oil still has zinc
too. You can get it in 15W-40 or straight 10 through 50
weights.

mart
============================================

[NE57]

Buddy, my account shows I have a $14 credit, so keep the info coming!

Really, I'll stop a second here and express my gratitude to everyone who has been so helpful on all subjects.