Comp Cams Dual Conical SR Valve Springs

[n2omike]

I did a quick glance, and haven't seen this topic... But, does anyone have any input regarding these?

http://www.compperformancegroupstores.c ... gory_Code=

[Newold1]

We did a 572 BBC with these springs on a mild low lash solid roller camshaft with about .750" lift at the valves. We used stainless hollow stem valves and the Comp tool steel small retainers. The springs measured about 200lbs on the seat @ 1.950" and about 625lbs open at 1.200". The customer did not have the budget for all titanium valves and retainers and this setup keep the valve train costs down and still lets this motor rev nicely to 7500 rpms without any valve train harmonics or float. I like these conical springs especially the dual sets that will handle more cam on solids and yet keep the sprung weights of the hollow stem valves and retainers down to allow higher rpm control on larger BBC valves.

[Charliesauto]

I did a quick glance, and haven't seen this topic... But, does anyone have any input regarding these?

http://www.compperformancegroupstores.c ... gory_Code=

I have not used dual conicals from Comp. In 2001, I did use some manufactured by Eibach, supplied to me by Dave Crower. Those had 180# on the seat and 680# open. Lift at the valve was in the .770" range, 5/16" stem titanium valves. Engine was in a NASACR Craftsman truck, ran it at Memphis Motorsports Park in the 2001 race. Ran it against a 10,000 rpm chip in qualifying, 9900 in race trim. That was about 700 rpm more than anything we had done before.

If we had known then what we know now(6mm stems, stiffer pushrods, steel rockers, better lobes, etc.), we certainly could have ran even more rpm. We sent the stuff to a major NASCAR shop at that time for them to Spintron test, they would not spin the stuff because it "only" had 180# on the seat. They said no way it could work, now I believe they are around 85-90lbs of seat pressure.

Definitely sold me on the dual conical design just could not procure anymore. Several years later, I talked to Osborne at PAC and he agreed a dual conical was a superior design, but he stated they were hard to manufacture. Apparently, Comp has figured out a practical way to build them.

[andyf]

I've used them before and they worked great for me. I have them on a 700 hp bracket race engine at the moment. I did a writeup for Hot Rod on the subject: https://www.hotrod.com/articles/dyno-te ... e-springs/

[CamKing]

I think you would be better off with a smaller diameter PSI springs
That spring is 1.442" at the top, and 1.657" at the bottom.
It's 150 @2.00", 630 @1.200", and a 1.115" Coilbind

You'd be better off, going with a spring that gets the overall weight of the spring down.
PSI # CT1575ML: 1.400" Diameter at both ends
It's 150 @2.00", 625 @1.150", and a 1.100" Coilbind
With the reduction in spring weight, you don't need as much spring rate to control the valve, and lower spring rate causes less valvetrain flex.

[BradH]

Without firsthand Spintron experience for a particular combination, how would someone determine whether a smaller & lighter spring package is sufficient to replace a known standard spring setup?

[CamKing]

Without firsthand Spintron experience for a particular combination, how would someone determine whether a smaller & lighter spring package is sufficient to replace a known standard spring setup?

Years of spintron experience has shown in multiple applications, that lightening the weight of the spring itself, has reduced the load requirements to control the valvetrain, and reduced valvetrain deflection.

Could there be exceptions? sure.

[BradH]

Without firsthand Spintron experience for a particular combination, how would someone determine whether a smaller & lighter spring package is sufficient to replace a known standard spring setup?

Years of spintron experience has shown in multiple applications, that lightening the weight of the spring itself, has reduced the load requirements to control the valvetrain, and reduced valvetrain deflection.

Could there be exceptions? sure.

Not arguing the benefits; asking how does someone know they've chosen the correct spring when they "downsize"?

I'm a$$uming speaking directly to the spring company or another source with experience using the smaller spring package, but didn't know what else would need to be taken into account.

[CamKing]

Without firsthand Spintron experience for a particular combination, how would someone determine whether a smaller & lighter spring package is sufficient to replace a known standard spring setup?

Years of spintron experience has shown in multiple applications, that lightening the weight of the spring itself, has reduced the load requirements to control the valvetrain, and reduced valvetrain deflection.

Could there be exceptions? sure.

Not arguing the benefits; asking how does someone know they've chosen the correct spring when they "downsize"?

I'm a$$uming speaking directly to the spring company or another source with experience using the smaller spring package, but didn't know what else would need to be taken into account.

They would need to know the weights of all of the valvetrain, rocker ratios, and acceleration rates of the cam profiles.

[digger]

What about the difference in life of the springs

[stealth]

https://youtu.be/uHw3mWYgO6M

David Vizard has a video on these

[gmrocket]

https://youtu.be/uHw3mWYgO6M

David Vizard has a video on these

GM have used beehives as far back as the mid 1950's on the Olds V8

[CamKing]

What about the difference in life of the springs

The PSI 1575 lasts longer then most springs we've run in circle track,
The Comp spring, I have never tested, but may depend on what Chinese company is making it for them.

[dfarr67]

What about the difference in life of the springs

The PSI 1575 lasts longer then most springs we've run in circle track,
The Comp spring, I have never tested, but may depend on what Chinese company is making it for them.

I was just about to ask about the quality of said springs and Comp in general these days- I don't know much but personally I don't go out of my way for their product.

[CamKing]

What about the difference in life of the springs

The PSI 1575 lasts longer then most springs we've run in circle track,
The Comp spring, I have never tested, but may depend on what Chinese company is making it for them.

I was just about to ask about the quality of said springs and Comp in general these days- I don't know much but personally I don't go out of my way for their product.

Unfortunately, it's a crap shoot. Some of their suppliers make great quality parts. Others, not so much.