Valve spring recomendation(s)

I bought some time ago, a solid roller Lunati cam minus the valve springs.

The Specs are 0.650 intake 0.641 exhaust. 252 int  259 exh Dur @.050  286 int  295 ex advertised  

109 ls

Can any one point me in the right direction to choose the right spring/retainer combination for my SCJ heads?

Thanks for any help offered!

D8ZZ wrote:I bought some time ago, a solid roller Lunati cam minus the valve springs.

The Specs are 0.650 intake 0.641 exhaust. 252 int  259 exh Dur @.050  286 int  295 ex advertised  

109 ls

Can any one point me in the right direction to choose the right spring/retainer combination for my SCJ heads?

Thanks for any help offered!

The PAC-1243 is the spring that came on the last version of those complete heads for a solid roller cam; 1.960" installed height.

rmcomprandy wrote:

D8ZZ wrote:I bought some time ago, a solid roller Lunati cam minus the valve springs.

The Specs are 0.650 intake 0.641 exhaust. 252 int  259 exh Dur @.050  286 int  295 ex advertised  

109 ls

Can any one point me in the right direction to choose the right spring/retainer combination for my SCJ heads?

Thanks for any help offered!

The PAC-1243 is the spring that came on the last version of those complete heads for a solid roller cam; 1.960" installed height.

Thanks! I appreciate the help!

Don’t forget to use titanium retainers, steel ones not the way to go.

Manley 221443-16 is also a popular option.

Actual page 70 of the link below. They list a 1.950 installed height for them.

https://www.manleyperformance.com/wp-content/uploads/2023/10/cylinder_head_components.pdf

dfree383 wrote:Don’t forget to use titanium retainers, steel ones not the way to go.

I am considering doing just that. Recommended locks? Just Comp or? "Super locks"?

supervel45 wrote:Manley 221443-16 is also a popular option.

Actual page 70 of the link below. They list a 1.950 installed height for them.

https://www.manleyperformance.com/wp-content/uploads/2023/10/cylinder_head_components.pdf

I will look into those, and see who has the best deal on Manley's or the pac's which ever i settle on.

D8ZZ wrote:

supervel45 wrote:Manley 221443-16 is also a popular option.

Actual page 70 of the link below. They list a 1.950 installed height for them.

https://www.manleyperformance.com/wp-content/uploads/2023/10/cylinder_head_components.pdf

I will look into those, and see who has the best deal on Manley's or the pac's  which ever i settle on.

With only .640" lift, a lot of people simply used the 954 Comp Cams on the earlier versions of those complete SCJ heads..

rmcomprandy wrote:

D8ZZ wrote:

supervel45 wrote:Manley 221443-16 is also a popular option.

Actual page 70 of the link below. They list a 1.950 installed height for them.

https://www.manleyperformance.com/wp-content/uploads/2023/10/cylinder_head_components.pdf

I will look into those, and see who has the best deal on Manley's or the pac's  which ever i settle on.

With only .640" lift, a lot of people simply used the 954 Comp Cams on the earlier versions of those complete SCJ heads..

Those are on the light side, I’ve had issues with them floating early.

dfree383 wrote:

rmcomprandy wrote:

D8ZZ wrote:

supervel45 wrote:Manley 221443-16 is also a popular option.

Actual page 70 of the link below. They list a 1.950 installed height for them.

https://www.manleyperformance.com/wp-content/uploads/2023/10/cylinder_head_components.pdf

I will look into those, and see who has the best deal on Manley's or the pac's  which ever i settle on.

With only .640" lift, a lot of people simply used the 954 Comp Cams on the earlier versions of those complete SCJ heads..

Those are on the light side, I’ve had issues with them floating early.

The 953 springs @ 1.875" installed height which originally came on those heads certainly didn't have enough force for anything other than that crate motor roller camshaft.
Using the 954 springs to directly replace them worked well but, they wouldn't handle a lot of valve lift.

rmcomprandy wrote:

dfree383 wrote:

rmcomprandy wrote:

D8ZZ wrote:

supervel45 wrote:Manley 221443-16 is also a popular option.

Actual page 70 of the link below. They list a 1.950 installed height for them.

https://www.manleyperformance.com/wp-content/uploads/2023/10/cylinder_head_components.pdf

I will look into those, and see who has the best deal on Manley's or the pac's  which ever i settle on.

With only .640" lift, a lot of people simply used the 954 Comp Cams on the earlier versions of those complete SCJ heads..

Those are on the light side, I’ve had issues with them floating early.

The 953 springs @ 1.875" installed height which originally came on those heads certainly didn't have enough force for anything other than that crate motor roller camshaft.
Using the 954 springs to directly replace them worked well but, they wouldn't handle a lot of valve lift.

The 954 spring with an XR292 floated just above 6400 on an old motor I had, changed them out for heavier spring and had no issues. The are probably better for a small block or something with lighter valves

dfree383 wrote:

rmcomprandy wrote:

dfree383 wrote:

rmcomprandy wrote:


With only .640" lift, a lot of people simply used the 954 Comp Cams on the earlier versions of those complete SCJ heads..

Those are on the light side, I’ve had issues with them floating early.

The 953 springs @ 1.875" installed height which originally came on those heads certainly didn't have enough force for anything other than that crate motor roller camshaft.
Using the 954 springs to directly replace them worked well but, they wouldn't handle a lot of valve lift.

The 954 spring with an XR292 floated just above 6400 on an old motor I had, changed them out for heavier spring and had no issues. The are probably better for a small block or something with lighter valves

Contrarily, testing with a Ford 514 crate motor, out of the box, with simply exchanging the valve springs to 954's, (at the same installed height with also the steel retainers as came on those SCJ heads), and using a Lunati #64034 Voo-Doo solid roller camshaft ... 7,200 RPM was where they stopped because power was falling off around 6,800 RPM.
That was already more RPM than that engine was meant to achieve with those heavy pistons at that 4.300" stroke and 6.604" length rods.
So, I guess the cam lobe profile has a whole lot to do with the running RPM level with whatever spring is installed ...

Mark Miller wrote:Randy a little off Topic i think you've said you have used the Lunati 73367 Springs before if so what's your thoughts on those?Thanks

Those have almost the same forces as the 954's from Comp; Just a tiny bit more.
But, will accept about .050" more valve lift so, I prefer them.