Small Block & Big Block Chevy Specific - Do you guys think this is enough spring?
Stroker 1500
07-21-2005, 04:53 AM
Im not to much of a expert when it comes to valve train but i was told that this would be plenty of spring for my cam...
Outer Diameter Top 1.255
Inner Diameter Top .870
Damper YES
Seat Pressure @ Installed Height 125 lbs. @ 1.800
Open Pressure and Height 383 lbs. @ 1.200
Coil Bind 1.100
Average Spring Rate 428 lbs./in.
Maximum Net Lift 0.640
The cam specs are
230/244 .510/.540 112LSA
Crane gold race 1.6 RR's
Where do you guys think i will have valve float problems with this setup?
FastRedChevy
07-21-2005, 05:17 PM
I think the lifters will pump up before those springs give you any trouble.
CTSV05
07-22-2005, 12:09 AM
If thats a hyd cam, I would say yes.
Stroker 1500
07-22-2005, 12:40 AM
If thats a hyd cam, I would say yes.
Ya its a hydraulic roller
CTSV05
07-22-2005, 05:38 PM
I would like to see more open pressure then, as the lifters are very heavy, and have a tendency to cause valve float at 6000 rpm or higher.
Maybe you could shim the springs since it appears coil bind shouldn't be an issue.
Stroker 1500
07-22-2005, 06:50 PM
I would like to see more open pressure then, as the lifters are very heavy, and have a tendency to cause valve float at 6000 rpm or higher.
Maybe you could shim the springs since it appears coil bind shouldn't be an issue.
There is one shim under the exhaust springs and 2 under the intake. How much does that increase the pressure?
FastRedChevy
07-22-2005, 11:19 PM
There is one shim under the exhaust springs and 2 under the intake. How much does that increase the pressure?
The shims are there to take up space to get the correct installed hieght. When the distance is too much between the retainer and spring you shim it if its not enough you have to cut it.
You dont want so much seat pressure that you are pushing the plunger down in the lifter. I wouldnt shim the springs you would be asking for trouble 350 lbs @ full lift is considered plenty for most hyd roller cams. Like i said your hyd roller lifters will give you trouble before the springs do. There should be no need to rev this much more than 6k anyways
Stroker 1500
07-23-2005, 02:27 AM
The shims are there to take up space to get the correct installed hieght. When the distance is too much between the retainer and spring you shim it if its not enough you have to cut it.
You dont want so much seat pressure that you are pushing the plunger down in the lifter. I wouldnt shim the springs you would be asking for trouble 350 lbs @ full lift is considered plenty for most hyd roller cams. Like i said your hyd roller lifters will give you trouble before the springs do. There should be no need to rev this much more than 6k anyways
The springs didn't need the shims to achieve the proper install height, they where put in there to give it a little more spring pressure. My engine builder is the one who shimmed it and said that i shouldn't have any problems with the spring setup i have. I just wanted to ask around for other peoples opinions, I completly trust my engine builder i just like seeing what other peoples thoughts are or how a setup could be better.
FastRedChevy
07-24-2005, 11:02 PM
Where did you get the specs of the springs you listed?
If its off the box and he did not install the springs at that hieght(1.800) those numbers mean nothing. What hieght did he install them at?
Why did he stay with a 1.25 spring? If i built that engine I would have gotten comp cams 986-16 or 987-16 spring they are probally the recommended springs with that cam if its a Comp anyways. Should say right on the card.
And Ive never told my customers they "Shouldnt have any problems" with my work. They leave knowing it will work.
What heads are you using?
Is the lift you stated figured with 1.5 or 1.6 rockers? If he shimmed them tight say .040" and installed them at 1.760 You have a max lft of around .600 lift. .580 lift if he used .060" shims. Assuming those number are with 1.5 rockers you would have about .544/.576 with 1.6 rockers you'd still be safe unless they are intsalled very low.