[staleg]

It looks like I will be going the Vortec-route for my 350 small block.

I have read about the Beehive spring upgrade. Two item numbers for what springs to use are mentioned: Comp Cams 29615 and 29618.

Which of them should I go for? I haven't been able to find out what's the difference between them?

 

[[email protected]]

Find a Comp Cams catalog. Or Call their tech line.

 

[Hogg]

The Beehive PN's are 26915 or 26918.

To use these springs on a non-GEN 3 engine you use 787-16 retainers. The GEn 3 and SBC use different diameter valvestems.

26918
http://www.compperformancegroupstor...roduct_Code=26918-1&Category_Code=GEN3Springs

26915
http://www.compperformancegroupstor...roduct_Code=26915-1&Category_Code=GEN3Springs
The 915's has seat load of 105lbs @ 1.800, open load of 293lbs @ 1.200", Spring rate of 313 lbs/inch
The 918's have a seat load of 125lbs @ 1.800, open load 367lbs @ 1.150", spring rate of 372 lbs/inch

Beehive retainers for Beehive spring use on non-GEN-3 heads such as Vortec L31 heads.
http://www.compperformancegroupstor...re_Code=CC&Product_Code=787-16&Category_Code=

For a milder cam the 915's will suffice. Either is a huge upgrade from the stock L31 springs. Comp did have an issue with the 918's breaking, supposedly they have fixed this.

peace
Hog

 

[staleg]

Thank you for a very informative answer!

 

[Hogg]

Thank you for a very informative answer!

No problem my friend.

In addition, the 2002-2004 LS6 springs are also a behive spring deisgn and will work on the GEN 1-E Vortec head. I have "heard" that the LS6 springs wont allow as much lift on a Vortec 305/350 heads as the Comp Cams 915/918 springs. I was told that the LS6 springs will rub on some part of the valvetrain.

I would like to see a side by side picture of a 2002-2004 LS6 Vette spring and a 915 or 918 spring.

Even if you were running a camshaft that was under the 0.480" lift limit of the L31/30 Vortec 350/305 heads, I would still upgrade to some sort of Beehive spring. I saw a test that showed 20+ lb/ft torque increases at a low 2500rpm on a BBC on an engine dyno.

The Beehive springs will not resonate at the same rpm due to their unequal diameter. An entire conventional spring will resonate at a certain rpm, causing the valves to not be controlled by the cam properly. Different sections of the Beehive spring will resonate at different rpms due to the varying diameter of its coils. I believe the Beehive springs are also wound out of OVATE (oval) wire. This allows for greater lift abilities before encountering coil bind, while still retaining strength.
IIRC, the 1996 LT4 Vette engine was the 1st V8 GM engine to utilize ovate wire. The LT4 springs are wound in a conventional manner with all the coils of the spring being of the same diameter.

peace
Hog

 

[staleg]

I have also read about the LS6 Corvette spring, part# 12589774.
According to GMPP's web page, max lift for this spring is 0,570".
On the LS6 motor, I suppose.

Maybe a dumb question, but if the spring can handle 0,570" lift on the LS motor, why can't it handle more than 0,520" when it's used on the Vortec heads?

Here's a link to GMPP:
https://store.gmperformanceparts.com/store/SelectProd.do?prodId=8106&redir=true&manufacturer=GM&category=Valve%20Spring%20components&name=Valve%20Spring&model=<!--12589774-->

 

[Hogg]

Because of the valve retainer to to valve seal interference.

peace
Hog