Valve Spring Selection

ldyracr · 10-05-2007, 08:19 PM

I was going to say the same thing about using the same spring again if I got three years out of them...lol.
I have used K-Motion and they just don't last long. I'm using Isky now and so far they have been good.

SlickVic · 10-07-2007, 09:33 AM

Well everything on the motor was good to atleast 8000 rpms. I only turned it at max in really good air, 7600. Most of the time is wasn't over 7400. But, what i don't understand is the springs that came w/ the dart heads, the ones that lasted 3 years, only have a max lift of 650. Im running a 670/625 cam.

Mike Hedger · 10-07-2007, 10:46 PM

Take out the lash from the total lift. .670 - .024 or so for lash. gets you under the .650 limit

Then if you figure in push rod and rocker arm deflection you loose a little more.

SlickVic · 10-08-2007, 04:36 PM

Lash on intake is only .012 which makes it .658...Whats deflection worth??

Mike Hedger · 10-08-2007, 04:51 PM

I checked mine doing cam lift X 1.7 and it comes out to the .808 the cam is advertised as. Then I put it all together like you are going to run it but with 0 lash and checked it again and I come up with .799 at the valve. I tried three different rockers and they were all the same + or - .001 (Crane wide body rockers). But I have around 305 - 310# on the seat and around 800# open spring pressure so it is going to make things move around. I also run the spring within .050 of coil bind and they seem to last longer. I would guess that is why yours lasted so long they were close to coil bind so they did not surge when they were closing the valve.

charliep · 10-08-2007, 05:39 PM

At 1.55 OD there are not many choices. I've had good luck with Comp Cams #999

SlickVic · 11-10-2007, 07:19 PM

Doing some measurements. Was looking at 1.6 rockers to give some added lift. After doing all the calculations, i ended up with .027 clearence before coil bind on the valve spring. Too small? Whats the recomended?

10-05-2007, 08:19 PM	#1
ldyracr Junior Member Join Date: Mar 2007 Location: Florida Posts: 11 Likes: 0 Liked 0 Times in 0 Posts	Re: Valve Spring Selection I was going to say the same thing about using the same spring again if I got three years out of them...lol. I have used K-Motion and they just don't last long. I'm using Isky now and so far they have been good.

10-07-2007, 09:33 AM	#2
SlickVic Junior Member Join Date: Jan 2006 Location: Maryland Posts: 81 Likes: 0 Liked 0 Times in 0 Posts	Re: Valve Spring Selection Well everything on the motor was good to atleast 8000 rpms. I only turned it at max in really good air, 7600. Most of the time is wasn't over 7400. But, what i don't understand is the springs that came w/ the dart heads, the ones that lasted 3 years, only have a max lift of 650. Im running a 670/625 cam. __________________ 87 Cavalier, 92 Corvette, 72 Nova, 68 Firebird

10-07-2007, 10:46 PM	#3
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Re: Valve Spring Selection Take out the lash from the total lift. .670 - .024 or so for lash. gets you under the .650 limit Then if you figure in push rod and rocker arm deflection you loose a little more. __________________ Mike Hedger S/C 4646 MPH Racing and Fabrication

10-08-2007, 04:36 PM	#4
SlickVic Junior Member Join Date: Jan 2006 Location: Maryland Posts: 81 Likes: 0 Liked 0 Times in 0 Posts	Re: Valve Spring Selection Lash on intake is only .012 which makes it .658...Whats deflection worth?? __________________ 87 Cavalier, 92 Corvette, 72 Nova, 68 Firebird

10-08-2007, 04:51 PM	#5
Mike Hedger Junior Member Join Date: Jul 2007 Location: Kemah TX Posts: 93 Likes: 0 Liked 1 Time in 1 Post	Re: Valve Spring Selection I checked mine doing cam lift X 1.7 and it comes out to the .808 the cam is advertised as. Then I put it all together like you are going to run it but with 0 lash and checked it again and I come up with .799 at the valve. I tried three different rockers and they were all the same + or - .001 (Crane wide body rockers). But I have around 305 - 310# on the seat and around 800# open spring pressure so it is going to make things move around. I also run the spring within .050 of coil bind and they seem to last longer. I would guess that is why yours lasted so long they were close to coil bind so they did not surge when they were closing the valve. __________________ Mike Hedger S/C 4646 MPH Racing and Fabrication

10-08-2007, 05:39 PM	#6
charliep Junior Member Join Date: Aug 2002 Location: Levittown Posts: 2 Likes: 0 Liked 0 Times in 0 Posts	Re: Valve Spring Selection At 1.55 OD there are not many choices. I've had good luck with Comp Cams #999

11-10-2007, 07:19 PM	#7
SlickVic Junior Member Join Date: Jan 2006 Location: Maryland Posts: 81 Likes: 0 Liked 0 Times in 0 Posts	Re: Valve Spring Selection Doing some measurements. Was looking at 1.6 rockers to give some added lift. After doing all the calculations, i ended up with .027 clearence before coil bind on the valve spring. Too small? Whats the recomended? __________________ 87 Cavalier, 92 Corvette, 72 Nova, 68 Firebird