I know this has been covered many times, Ive been searching and reading old posts. It has been stated many times that the 113 head with aftermarket springs will lift up to .525 before hitting the guides and the comp 981s are a sure thing. The problem is when I was about to buy a set i was looking for the recommended install height and found that they are only recommended to .490 lift. Did they change the design or has everyone been ignoring the recommended max lift? The specs show an installed height at 1.7" and coil bind at 1.15, giving .550 when bad things happen. The cam i want to run has a .510 exhaust lift and .040 seems like plenty of clearance to me. I called comp to verify they numbers were correct and he said recommended lift really is .490. Does anyone know if they design changed or if everyone ignores their recommendation. Any other spring recommendations would be appreciated also. Sorry this is so long, thanks for the help.

 

After more searching I found that the z28 springs(good for .600 lift) from scoggin dickey should drop right in. I called SD and verified they would work and probably even work with my stock retainers and locks. He also recommended going with factory ls6 beehives and comp retainers as another option. Any opinions?

 

.550 to coil bind is absolute max. You really want about .050-.060" clearance to stay out of trouble. Hence the .490" recommendation. Have I done a smidge over .500" with them? Yes, and they worked fine, but you're on the bubble there. Not much room for error.

Beehives are expensive, is their only drawback. Try the Z28 springs with your stock retainers- they'll probably work just fine and won't break the bank.

You're running the ZZ4 roller cam, I assume?

 

Comp has 2 springs under the 981 part number the other is the beehive springs I have on my motor. There 26981 but a lot of people call them 981 springs and there the ones that have the .525" lift capability. I would not use the LS6 springs there designed for a 1.8" install height.

 

Howards #98212 $50 http://www.competitionproducts.com/C.../products/419/

 

The cam is the comp xe 08-503-8, 224/230 .503/.510 12lsa +4.

I wanted to stay with stock drop-ins to save on cost but I'll go to the beehives if I have to. I've looked at the 26981 springs and they seem to fit the bill but they are $160+$55 for the retainers at summit.

Are you saying that the ls6 can't be installed at 1.800 because I don't have the spring pocket to do it, or is there something else? I called comp about spring pressures and they recommended 130-140# closed and 280-320# open, that puts the ls6 out anyway.

Manley 22410 are 1.26 OD and pressures fit the bill @ 1.75 installed height. SD Z28 HD springs are good on pressures but are also installed @1.800. The non HD might work with 110#@1.7 and 290# open. I guess I could order the Manley springs and test fit my stock retainers. That or go with the more expensive beehives.

Those Howards seem OK but their open pressure is 115#. Their coil bind is .600 though, that gives me .090 clearance. I wonder if my factory retainers will work with them.

Leaning toward the Manley's right now. Smaller OD than the Howard springs and more seat pressure at the same installed height. $75 at summit.

 

Factory retainers work with the Howards, I have used them and stock retainers on a few engines. In fact my vortec headed 355 has those Howards springs and the stock vortec retainers.

 

Good info, thanks. I'm going to try the Manley's since they fit the pressures that comp wants. If for some reason they won't work with my factory stuff I'll go with the Howards. I'll bump this thread with the results.

 

Here's what I have found. The Manley springs 22410 drop in and fit great. They will work with the factory retainers however, because of the overall height of the factory retainers I could only get about .460 lift before they hit the valve seals. After fitting the standard steel Manley retainers 23651 I was able to get .590 lift before hitting the seals, plenty for the .510 I was wanting to run.


I did find out that my engine has been rebuilt at some point so I don't know what, if any, headwork has been done.


I know that its highly unlikely that my factory pushrods would fit after a cam change and after some more reading I found that when you change to stiffer springs you need stiffer pushrods, the stockers cannot take the added force. There are plenty of reports of stock pushrods bending and falling out of their cups or worse, binding into the edge of the lifter and rocker and breaking valve springs causing engine damage. Its worth the $100 to get hardened pushrods.


Factory rocker arms cannot handle more than about .470 lift because of their short slot where it mounts to the rocker stud, also they are known to be inaccurate in their lift ratio. Long slot rockers are an option as well as opening up slot on the factory rockers but I chose to go with a roller tip rocker from Comp Cams 1417. They only needed minor clearancing on the drip tabs which are important for keeping oil in the center section of the rockers. About .030 off the inside to cylinder .750 inch up from bottom and .030 off the end is plenty for clearance.


So that's kind of a newbies guide to valve springs in a d-port alum 113/zz4 corvette head, what I was looking for a couple months ago. I hope it helps someone.


Also, this is a good read about valvetrain.


http://www.aa1car.com/library/perfor...valvetrain.htm