Do my heads have to be machined for dual springs?

 

Are you meaning "real" dual springs or a spring with a damper? If a spring + damper, no milling is required. I don't know about real dual springs, though.

 

yeah, double springs not including the damper. A spring within a spring. Comp cams website says machining required but don’t know what that entails

 

Your valve spring pockets may need milling for the correct spring height to be achieved, and your valve guide may have to be machined for smaller valve guide seals to clear rhe inner spring

 

Why do you think you need dual springs ?

 

Bought a cam, then realized it called for a spring that was double. Didn’t know about this. Maybe someone can recommend single spring that will work? The cam is 485/.490 lift.

 

455 and my shortest installed height is 1.65”

 

Many years ago I had heads done with double springs, the shop said there wasn't any room now for valve stem seals... so none were installed.

 

Spring pockets are close to the water jacket on Olds heads; don't recommend cutting the spring pockets. Plenty of dual springs available for you or you may want to look into the "beehive" springs that are available. If you choose dual springs your valve guides will most probably have to be machined for smaller outside diameter valve seals. Look to your cam manufacturer for valve spring recommendation.

 

I always thought if you stayed under .500 lift then stock springs were ok

 

What brand cam ? What Duration ? Hydraulic grind ? Flat tappet ? RPM range ? Why did you choose that cam ?

 

I also thought under .500 lift stock style were fine, i am running stock style spring with a dampner and my cam lift is .500.

 

The UD cam in my engine is that lift and I used regular factory replacement springs with a damper, and the engine will easily rev to 5600+ RPM.

 

comp cams xe224-230 hydraulic flat tappet

https://www.compcams.com/xtreme-ener...e-260-455.html

 

New 1970 W-30 valve springs and dampers shimmed to 1.67" will be more than enough for that cam.
......Just my two cents worth.

 

Thats what I’m thinking

 

Is there any way to find out specs on factory springs? Looked in service manual but it didn’t say, I sent an email to Supercars Unl. But never got an answer

 

Contact Comp Cams directly

 

A dual valve spring in most all cases requires the reduction of the seal area of the guide. The factory guide is around .590 and then when a seal is installed onto it, it will typically run interference with the i.d. of the inner spring on a dual spring. We frequently reduce the o.d. of the guide and install a .530 seal. This will allow for a dual valve spring. You can check out lots of tech tips and videos at Olds Performance and Machine on facebook. Thanks.

 

Great info, thanks

 

Ditto what Ralph mentioned in post #15 above (if you can find them). They are considerably stiffer than the non W30 valve spring and should work fine up to .500" lift; and you can use stock valve seals with them. On a separate but similar note, if someone has the means to research this, I recall a Chevy 409 factory valve spring that had the same specs as the Olds W30 spring.