340 hp valve springs

[William F.]

My '62 340 hp 327 with 097 cam pulls strong but not sure of age of valve springs. Danger if original to motor? Any way to check their 'Health"?If I decide to change springs and keepers, does GM still offer parts or NAPA? Part numbers?Thanks

[John H.]

Re: 340 hp valve springs

If I decide to change springs and keepers, does GM still offer parts or NAPA? Part numbers?Thanks

William -

Uses the same springs as any other Chevy. GM #3911068 or Federal-Mogul/Speed-Pro #VS-677 (F-M makes the GM spring for about 1/4 the price).

[Joe L.]

Re: 340 hp valve springs

William -

Uses the same springs as any other Chevy. GM #3911068 or Federal-Mogul/Speed-Pro #VS-677 (F-M makes the GM spring for about 1/4 the price).

John and William-----



The GM #3911068/ Federal-Mogul VS-677 can be used for the 1962 application but it's not the spring originally used or one that replaced the spring originally used. Pre-1967 Corvette small blocks originally used valve spring GM #3735381. Believe it or not, that valve spring remains available from GM to this very day. It's also available from Federal-Mogul under their part number VS-521.

The 3911068 and 3735381 are fairly similar in spec although there are differences. If I were rebuilding or replacing valve springs on a 1955-66 small block, though, I think I'd use the 3735381. Why? Well, I figure if GM has not replaced the 3735381 with the 3911068 by now, there's got to be a good reason for it.

[Joe M.]

Re: 340 hp valve springs

"F-M makes the GM spring for about 1/4 the price)."

The price diff is sobering!

[Dan D.]

Re: 340 hp valve springs

Connecting rods are probably a bigger risk than the springs.

-Dan-

[Joe L.]

Re: 340 hp valve springs

"F-M makes the GM spring for about 1/4 the price)."

The price diff is sobering!

Joe-----


Yes, the price difference is sobering. However, I've never been able to confirm that the GM spring and the Federal-Mogul aftermarket spring are exactly the same piece. I've compared them side-by-side and they do not appear to me to be exactly the same and if they came off the same manufacturing line I would expect them to appear exactly the same.

Consider this: Federal-Mogul is both an OEM supplier and an aftermarket supplier. Completely separate divisions of the company manufacture aftermarket and OEM parts, often in completely different manufacturing plants. Aftermarket parts are sold into a HIGHLY competitive market in which price is everything. OEM parts are generally higher quality to meet manufacturer's specifications for parts used in new cars.

Still, is it possible that a valve spring sold in, say, a GM box of part number 3911068 is exactly the same as one sold under Federal-Mogul part number VS-677? Yes, it's possible but I'm not yet absolutely convinced they are.

[Don L.]

Re: 340 hp valve springs

Since I spend my Monday through Friday in the engine valve spring business, I'll share that aftermarket springs CAN be made from "different" materials. The performance and cost of OEM vs SOME aftermarket material is dramatically higher. Additionally, SOME "off shore" processing vs North American processing is another contributor to these differences.

As Forest Gump says, "that's all I have to saaayabout that..."

BTW, I know Federal Mogul, however, I don't recognize them as an engine valve spring manufacturer. That doesn't necessarily mean that they don't sell them.

[Jerry G.]

Re: 340 hp valve springs

I've been using "Beehive" springs in my race motor. They run up to 7000 regularly and don't kill the stamped stock rocker. Anybody else using these. They seem to be holding up very well.

[Edward J.]

Re: 340 hp valve springs

Connecting rods are probably a bigger risk than the springs.

-Dan-

Dan, I agree, it was a rare occasion to see a valve spring break on a stock GM V8 engine of our vintages. I would be more leary of those rods with the 5/16 studs,

[Joe L.]

Re: 340 hp valve springs

Dan, I agree, it was a rare occasion to see a valve spring break on a stock GM V8 engine of our vintages. I would be more leary of those rods with the 5/16 studs,

Edward-----


They were 11/32" rather than 5/16". However, the big deficiency in these rods was the basic design of the big end and cap. But, at least they were forged steel. Some other engines of the period used cast iron rods.

[Joe C.]

Re: 340 hp valve springs

I've been using "Beehive" springs in my race motor. They run up to 7000 regularly and don't kill the stamped stock rocker. Anybody else using these. They seem to be holding up very well.

I use them. Because of lighter inertial weight, spring rates can be lower than a standard spring when controlling identical weight valves on identical cams. They run cooler as well.

[Joe L.]

Re: 340 hp valve springs

I use them. Because of lighter inertial weight, spring rates can be lower than a standard spring when controlling identical weight valves on identical cams. They run cooler as well.

Joe and Jerry-----


I've never used them but the more I've learned about them, the more I've convinced myself that they are a product of modern technology that could be used to great advantage when retrofitted to older engine applications. I feel the same way about hydraulic roller cams.

[John H.]

Re: 340 hp valve springs

Joe and Jerry-----


I've never used them but the more I've learned about them, the more I've convinced myself that they are a product of modern technology that could be used to great advantage when retrofitted to older engine applications. I feel the same way about hydraulic roller cams.

Joe -

We've used them on the Viper V-10 for the last 13 years, to take some weight and harmonics out of the valvetrain (which also includes Rhoads hydraulic roller lifters to "calm down" the low-rpm valve timing events to get through idle emissions).


ValveGear800.JPG

[Joe L.]

Re: 340 hp valve springs

Joe -

We've used them on the Viper V-10 for the last 13 years, to take some weight and harmonics out of the valvetrain (which also includes Rhoads hydraulic roller lifters to "calm down" the low-rpm valve timing events to get through idle emissions).


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John------


Speaking of Vipers, there's one less in the world than there was a few weeks ago. It seems that some fellow from Hayward with a 2003 Viper was on his way to the Good Guys car show in Pleasanton in caravan with some other friends, many driving Corvettes. They were driving through Niles Canyon which is a fairly "curvaceous", 2 lane road. For some unknown reason he crossed the center line (which has a pair of double yellow lines and a rumble strip) and struck a Nissan pick-up truck head-on. Both vehicles were traveling at or above the speed limit of 45 MPH for a closing velocity of at least 90 MPH. The Viper basically disintegrated. It so happens that my nephew, an Alameda County sheriff's deputy, was on duty in the canyon and he pulled the victims out of both wrecks. Remarkably, the 3 people in the pick-up survived with only minor injuries but the driver of the Viper was not so fortunate. My nephew said that he was alive when he pulled him out but not for very long afterward and was pronounced dead at the scene. He was 46.

I go through the canyon a lot and there was quite a bit of debris left by the side of the road, mostly from the Viper. I picked up an "artifact", pictured below.


DSCN2859.jpg

[Bob I.]

Re: 340 hp valve springs

Any idea the lbs/in loss, after a new spring installation, settles in.
Bob