1acesmith

Is a Beehive valve spring a stronger single spring?

Just bought a Comp Cams #42-223-4 cam and lifter set for my 69 455 http://www.compcams.com/Company/CC/c...csid=1171&sb=2 .

Note on the specs says that stock springs can't be used and shows Comp Cams #995-16 Dual springs as the correct parts to use. http://www.compperformancegroupstore...ct_Code=995-16 .

The heads were recently rebuilt and are on the motor. Comp Cams has a Beehive spring set #26995-16 http://www.compperformancegroupstore...Category_Code=.

I would prefer not to have to pull the heads again for machining. Does anyone know if a Beehive spring is a suitable alternative to dual springs?

joe_padavano

Depends on the specific spring specs, but in general, the point of a beehive spring is to allow the coils to "nest", which lets the spring compress more for a given wire diameter before coil bind, or conversely, allows you to use thicker (stiffer) wire for a stiffer spring with the same compressed height as a conventional spring. Whether that particular beehive spring is as stiff as a double conventional spring depends on the specifics of each, but it's possible.

1acesmith

Thanks Joe...
I just found the Comp Cam spec sheet where I believe the beehive is listed as an option. Its on page 235 in this link http://www.compcams.com/catalog/COMP...10_234-239.pdf

The footnote says machining is required so I'm back to that problem. I was hoping to be able to avoid the machining.

1acesmith

I use the car for street not track and doubt I'd ever get into the high RPM's that could cause valve float. I'm concerned about the long term durability if I use the stock springs.

compedgemarine

call the compcams tech line and ask them. they are very helpful and can tell you if you really do need to machine something or not. I have talked to them several times for different issues and they have always been great to deal with.

1acesmith

I'll call them first thing tomorrow. Thanks.

Run to Rund

Do your research and you won't have to machine anything. The lift isn't much more than the W30 cams and they used stock retainers and seals. Just be sure the seals you use don't have too much height over the valve guides. Isky 507STA and many other retainers are shorter underneath, giving more retainer to guide clearance. Check the installed height and pick a set of springs from Comp, Isky, etc. to get the pressures you need at the installed and open heights.

Lee_A

Do you KNOW your installed height?

If not, do you have the tools and ability to measure the installed height with the heads still on the motor?

If you do, do you have the tools and ability to determine what the ACTUAL pressure of the spings will be at your installed height, and how to adjust the pressure?

If you don't have those areas covered, you really won't know if you are making your spring situation better or worse, by changing the springs. You would be best served by taking the heads off, and taking them to a professional.

Springs can break. When you start putting more aggressive cams in, and driving the car more aggressively, springs are MORE likely to break. With double-springs, your motor will lose some power if one of them breaks, but you won't drop a valve. If you only have a single-spring setup (beehives), the valve can drop and NASTY things happen.

Many high performance LS builders REMOVE the beehives, and go with dual-springs.

Lee

1acesmith

I called Comp Cams this morning. They said their footnote on machining the heads for dual springs is generic and some heads don't require machining. They were unable to say if my C heads would need it or not. I would prefer dual springs. Has anyone installed dual springs on C heads and didn't machine the heads for the springs? Also since I'm an idiot about this, I'll check with the machinist to see if the old springs were replaced when he rebuilt the heads. Appreciate everyones help. Steve

1acesmith

Mondello said their kit SK247SP is a stiffer spring for my 69 455 that wouldn't require machining. I imagine I'd have to pull the heads to change springs anyway?

Run to Rund

See my previous post. You won't have to machine anything. If you have C heads, the installed height after a valve job will be between 1.68" and 1.75". Comp has several sets of dual springs on the shelf, as does Isky etc. that will give you about 120 lb. seat and 320 lb. open, which is plenty for your cam up to about 6000 rpm. The stock retainers aren't good for dual springs as they don't have a seat for the inner spring. Isky 507STA do, but are machined for the slightly bigger ID inner spring they sell rather than Comp's. If the height is close to 1.75", you can use Comp 984 and Isky 906AM springs with Isky 507STA retainers. If more like 1.68", use Comp 990 outer springs instead of the 984.

1acesmith

Run To Rund....thanks for the info. Very helpful

cutlassefi

You don't need a dual spring for that cam. Something with 115 on the seat and 275-300 open is fine. You're making this harder than it needs to be imo.