Valve springs

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Jtega
Posts: 3
Joined: March 4th, 2023, 9:59 am
Stroker Displacement: 4.6
Vehicle Year: 1995
Vehicle Make: Jeep
Vehicle Model: Xj cheroke

Valve springs

Post by Jtega »

I have a question. I have a lunati cam with .504 and .527 lift. I found some valve springs and I'm curious if the isd will work
Otd-1.465
Isd-.800
Open spec-100#@1.875
Closed spec-300#@1.345
Jtega
Posts: 3
Joined: March 4th, 2023, 9:59 am
Stroker Displacement: 4.6
Vehicle Year: 1995
Vehicle Make: Jeep
Vehicle Model: Xj cheroke

Re: Valve springs

Post by Jtega »

Jtega wrote: March 4th, 2023, 10:33 am I have a question. I have a lunati cam with .504 and .527 lift. I found some valve springs and I'm curious if the isd will work
Otd-1.465
Isd-.800
Open spec-100#@1.875
Closed spec-300#@1.345
It's for a 4.6l long arm stroker
Randy Bobandi
I made it to triple digits!
I made it to triple digits!
Posts: 152
Joined: December 22nd, 2020, 8:50 am

Re: Valve springs

Post by Randy Bobandi »

Jtega wrote: March 4th, 2023, 10:33 am I have a question. I have a lunati cam with .504 and .527 lift. I found some valve springs and I'm curious if the isd will work
Otd-1.465
Isd-.800
Open spec-100#@1.875
Closed spec-300#@1.345
We'll have to assume your diameter measurements are base diameters. The stock Jeep spring seat OD is 1.3125" and the ID is .775". So the springs that you "found" are larger than the spring seat OD in the cylinder head. Here's the thing, in order to run over .500" of valve lift, the spring seats have to be machined anyway. So it is absolutely possible to run 1.400"+ BASE OD springs. You just have to machine the spring seats pretty deep, flat and run spring seat OD locators.

There's another problem with the springs that you "found". Are you planning on running the valves at a 1.875" installed height? That would be strange and I'm not sure if it's even possible. You would have to machine the spring seats down at least .235". More like .295" due the springs needing OD locators which are .060" thick. That is way too much material to remove from the area of the cylinder head that under immense pressure.

If you used those springs, but installed them at 1.800", you be into coil bind at .455". That's not gonna work either. So forget those springs.

We have identified the appropriate springs for .500"-.600" valve lift.

For .525" max lift, use Comp 26981 springs. These install at 1.700" and require at least .060" removed from the spring seats. They bind at 1.115". So at .527" of valve lift they would give you a distance to coil bind of .058" Seat pressure of 110#, and an open pressure of 294# at .527".

For .600" max lift, use Comp 26918 springs. These install at 1.800" and require at least .160" removed from the spring seats. They bind at 1.140". So at .527" of valve lift they would give you a distance to coil bind of .133". Seat pressure of 125#, and an open pressure of 321# at .527".

I would recommend that you run the 26981 springs. .058" distance to coil bind is near perfect. Plenty of pressure and a reliable beehive design.

Here is a spreadsheet of applicable springs for .500"+ valve lift.
valvespringsjpg.JPG
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Jtega
Posts: 3
Joined: March 4th, 2023, 9:59 am
Stroker Displacement: 4.6
Vehicle Year: 1995
Vehicle Make: Jeep
Vehicle Model: Xj cheroke

Re: Valve springs

Post by Jtega »

Thank you. You're a life saver bud
Russ Pottenger
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Posts: 889
Joined: August 15th, 2009, 1:27 am
Stroker Displacement: 4.7
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee

Re: Valve springs

Post by Russ Pottenger »

If you’re willing to upgrade to a LS valve I have a drop in valve spring that doesn’t require the valve spring seat to be machined.

It’ll be about 100 on the seat and 280-285 on the nose.

Valves, Springs, Chrome Molly retainers, and a set of LS locks starting a $350.00 a set.

Welcome to reach out to me.

Thanks,
Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Cell (626) 673-2203
Email: [email protected]
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